ENTO 2010E Ultimate Quizlet

Life in the Undergrowth

lafcutter ants, cleaning the refuse out of their nest. Every single one of these tiny creatures knows where it's going and what it's going to do when it gets there. And furthermore, there are about 10 million more of them in this huge underground nest beneath me. They're all members of one highly organised society. But they're not the blindly mechanical, robotic slaves that we once thought they were. Indeed, we now know that every insect society is full of conflict, power struggles, and mutinies. Social insects construct the tallest of all non-human buildings. Like these huge termite hills here in Australia. They protect their colonies with great ferocity. They increase the size of their societies at an alarming rate. And they're capable of mobilising huge armies to make wars on their neighbours. But how did these great communities develop? Most insects like this little sand wasp here in the deserts of Arizona live solitary lives. This one has just dug a hole in which she is going to lay eggs. But then she does something else. She will cater for as yet hatched young by putting a caterpillar inside that hole on which they can feed. And that is a very important stage in the development of the social life. In fact, it's the very basis on which all the great insect societies are built. This species of wasp, however, is still at the stage of working alone. After stocking each nest for the caterpillar, she blocks the entrance to deter thieves. Her burrow maybe several centimetres deep. At the bottom lies the paralyzed caterpillar and on its back, that is now a wasp grub feeding on it. The female wasp makes several of these nests a few feet apart and stocks each of them with living food for her young. Can there be more hardworking mother? Despite all her attempts at parental care, the vast majority of her young will not survive. She's too busy hunting for more caterpillars to be able to guard all her nest sites. Back in the distant evolutionary past, other wasps started to build their nests alongside one another. And here on the coast of Panama, paper wasps still do so. Grouping their cells together means that even though you will have to leave your eggs to collect food, there will always be someone around on guard. The wasps are all sisters. But as often happens, one tends to dominate the rest. She starts to bite her sisters with great brutality. She is the boss, the queen, the others may build cells, but only she will lay eggs in them. Many of the genes in these eggs are the same as those carried by her sisters. And the sisters look after the eggs as if they were their own. And now, because the nest is so well guarded, the family rears more young than if each female were to nest alone. So, as each egg is laid, the sisters take steps to protect it. To do that, they need building materials. They chew wood into pulp and then use it to build a protective wall around each egg - a cell. So a colonial nest begins to grow. With more and more young females needing to be fed, the adults go hunting. Each returning wasp bringing prey, is greeted by the other workers. They squabble over food. The queen takes a lion's share. Those of her sisters and daughters who are higher up on the social scale also get big helpings, because they bully the junior females. In fact, the food isn't eaten by the adult who wins it. She feeds it to her developing younger sisters. This grouping and enormous single-sex family was the first step towards the development of insect societies containing millions of individuals. And it's still their basic structure. The forests in which the first wasps hunted were dominated by horsetails and conifers. They relied upon the wind to distribute their pollen. But then about a 100 million years ago, a new kind of plant appeared, which recruited insects to do the job. And they did it with nectar loaded flowers. Some of these recruits then abandoned hunting and concentrated instead on this new food. They became bees. Today, there are about 20 thousand different species of them. This queen bumble bee mated at the end of last summer before she hibernated. But now she's gone off to look for a new home because she's ready, at last, to lay those eggs. She may take some time to find just the right place. A deserted mouse hole. Ideal. First, she makes a little wax pot in which she lays a group of fertilised eggs. In due time, these hatch into young females. The queen now has her subjects. A colony has been established. From now on, she does little building herself. Her daughter's take on that job and they use a material that no wasp ever had. It oozes from between their body segments. It's wax. The queen also produces a chemical substance that permeates the nest and keeps her daughter's sexuality in check. Their job is not to produce eggs, but to look after their younger sisters. More and more young workers are horning themselves out of their cells. They don't have to travel far to find their first adult meal. In fact, to begin with, they stay inside the nest, helping with nest duties, feeding the young, keeping the place clean, building more cells. After a few days, they begin to venture outside the nest to help in collecting food. If the colony is to be properly nourished, they must gather not only nectar, but pollen. Nectar they transport in their crops, but pollen is held in a tiny ball by a brush of stiff hairs on their two hind legs. A worker can carry a lump weighing half as much as she does herself. Each bundle is carefully unloaded into one of the storage cells. The pollen isn't eaten by workers. They unselfishly bring it back for the larvae. For its rich in protein and the central food for their development. By the late summer, there may be more than 200 workers in the nest. Although the colony is now close to its maximum size, the queen is still laying. But these batches of eggs are different. She's now stopped producing the chemical substance that repressed the sexual development of her daughters. So these eggs will develop into new queens. The change effects not just her eggs, but her existing daughters, the workers. No longer restrained by the Queen's chemical control, some workers have started laying their own eggs. This doesn't suit the queen and she destroys them. The workers haven't mated, but their eggs can develop nonetheless and become males. The queen eats as many of these eggs as she can find because, as well as queen eggs, she's also producing male eggs and can't tolerate the competition. She keeps such a close watch that she manages to destroy the worker's eggs almost as soon as they're laid. The end of summer approaches. There's now anarchy in the colony. The social order has collapsed. Many of the workers whose eggs are being destroyed by the queen start to attack her. The onslaught is brutal, no quarter is given. Eventually, they sting her to death. The end of the colony has come. None of the workers will survive the winter. But the young queens will have left the nest and found males. It's they who will establish new colonies next spring. Bumblebees have a particular problem. In any given area, there's only a limited number of holes that are suitable for nests. European honey bees, which in the wild, nest in holes in trees, have similar difficulty. But some bees have adopted a very radical solution, a very brave solution to that difficulty. They nest out in the open, but at the top of tall trees, sometimes very tall trees. These are the giant Asiatic bees, the biggest of all honey bees. They're found from the Himalayas all the way down to Southeast Asia. These colonies are in Malaysia. They defend themselves with stings. Very, very powerful stings, which is why I have to wear a bee suit. And it's not just against one bee that you have to guard yourself. Because if one bee attacks you, it releases a pheromone, a chemical signal which is detected by the others in the comb. And within seconds, there will be hundreds, indeed, probably thousands of them all around you, launching a mass attack and stinging you. And some of those stings can actually go through a bee suit, so something to be avoided. Stinging is a very expensive form of defence because when a bee loses its sting, it dies. So it's better for the colony to warn predators off before they have to fight them off. And they warn them with some dramatic displays. I've got a reproduction of a hornet, which is one of the main enemies of bees. And I'll see if I can get them to do it. Just watch. There. See, there's a moving wave which passes over the surface of the colony. And that not only produces an impressive pattern, but it also makes it very difficult for any aggressor, like perhaps a hornet, which eats bees to actually land on that moving carpet of wings. The colony's great treasure of course, is it's huge store of honey. This is produced from nectar, which the bees industriously collect from flowers. They systematically expose it to the air so that the water it contains evaporates. And the nectar becomes sweeter and thicker. Eventually it turns into honey. The combs in which they store it are continuously guarded by the covering of bees. They cling so thickly, that it might seem that nothing could get past them. But some thieves know how to do so, particularly at night. A death's head hawk moth flies over the surface of the colony and go so close to it, that the bees are alarmed enough to waive their warning. But the moth is not put off. It wants honey. Amazingly, it manages to land on the carpet of bees and quickly pushes its way through them. A quick sip of honey, and it's off. It succeeds because although it looks nothing like a bee to our eyes, it has camouflage itself with the smell of pheromone that convinces the bees that it's one of them. But in spite of such raids, bees, thanks to their stings, retain their precious honey. Precious because it is that that enables them to survive a season without flowers. While some descendants of the wasps became flower foraging bees, others remained hunters, but went down to the ground to search for their prey. There, wings were more of a hindrance than a help. And these insects lost their wings for most of their lives. They are the ants. These are wood ants, and they build nest even bigger than those of the giant bees. This one is in the pine forests of the Alps. Hunting parties go out from the nest along well-established trails to search for prey. Anything their own size is quickly overpowered. But by working together, wood ants can tackle prey much bigger than themselves. Some caterpillars are covered with stinging hairs, but the ants cut these off one by one. And they can slice right through a beetle's hard armour. Now they are attacking another hunter, a spider. Everything they catch is taken back to the colony to be shared by those workers that stayed at home looking after the young. The disadvantage of building a huge nest like this is that you're very obvious to predators. But these ants have a very effective way of defending themselves. Watch. The unmistakable acrid smell of formic acid. Most ants, like their wasp ancestors, have stings, but not these wood ants. Instead of injecting poison, they squirt it, and very accurately, too. They don't eat just meat. They also visit aphids that sit in the branches above, drinking the pine tree's sap. This contains more sugar than the aphids need. So the ants drink the excess. And they collect it just as fast as the aphids excrete it. They carry it back to the nest, but in this case they transport it inside their swollen stomachs. In fact, this liquid, honeydew, makes up more than two-thirds of the colony's diet. All these wood ant nests are connected to one another by trails. And indeed they're also genetically related to one another. There are some 1200 of them in this one patch of forest. And that makes this what is thought to be the biggest supercolony of ants in the whole world. By mid June, the super colony is ready to reproduce. Out of every nest, among the workers, come individuals with wings. Some nests produce only males. They take off in droves. Other nests produce only females. Both sexes now that they're winged look remarkably like wasps, a reminder of their ancestry. Unlike wasps, however, these flyers are not very confident about getting into the air. Males and females assemble in the nearby meadows. The queens lay down chemical trails so that the males may quickly discover exactly where they are. And the males are quick to take the hint. The males only live for a few days, and they mate as quickly and as frequently as they cam. A queen, on the other hand, may live for as long as 10 years, and a single mating will provide her with enough sperm to last for her entire life. For a female, mating is often a bit of a battle. Sometimes she has to bite a male to make him release her. Sometimes she has to hang on to him because he's impatient and wants to move on. The newly mated queens gather together in the undergrowth. Here, they shed their wings. They found their males. So their travelling is over. Now, each must find an existing nest in which to lay her eggs. This one encounters a column of workers. A wood ant nest may contain as many as 1000 queens, but will these workers allow her to be one of them? If they don't, they will bite her to death. She's been accepted. The workers have detected chemical clues on her body that tells them that she's originally from one of the nests in the supercolony. She's large and fat. Walking is not easy for her. A single worker carries her along the trail back home, perhaps even to the same nest in which she started life. Ants live almost everywhere. The water falling in this mangrove swamp in Australia exposes in the wet mud an ant's nest. Every time the tide recedes, the ants must repair any damage that the water may have caused. Collapsed entrances must be reopened and blocked tunnels cleared. Now that the mudflats are exposed, the ants hurry to collect what food the tide might have delivered. But there are still some stretches of water to be crossed. The surface tension of the water supports them as they dance across it. Sometimes they actually swim. And there has indeed been a new delivery of food. But the tide has also created a problem. It is washed away the chemical trails that marked the frontiers of their territory. So there's now no clear boundary between them and ants belonging to a neighbouring colony. The interrogation of a stranger is complex and detailed. Who are you? Where'd you come from? Answers are readily given and accepted. But every now and then they have to fight to settle the question. They may have sorted out their disagreement, but now there is a bigger threat to both of them. The tide is turning again. They must get back to the safety of their nests. While the tide has been out, larvae and pupae have been moved around the nest to keep them at the temperature needed for their proper development. Now, they must be moved again, for the nest is not watertight. Many of the tunnels and chambers are flooded with every tide. There's no time to waste. But the water doesn't reach every part of the nest. For the ants have constructed bell-shaped chambers that trap pockets of air and so create refuges where the adults and the young can sit out the high tide. Here in Arizona, the problem for an ant is not too much water, but too little. The rainfall is so low that there's hardly any vegetation and very little to eat. So an ant has to be prepared to eat whatever it can find. There are seeds, but seeds are very tough and you need very powerful jaws to crack them. But then that's exactly what these harvester ants have got. They make an intensive search of the sand. Almost any seed will be collected. Food around here is very scarce. They can't afford to be fussy. They carry their gleanings back to the nest to store it in larders, many of which are several metres below ground. But like the mangrove ants, they must work fast. The desert warms quickly and before long the heat will be intolerable. By night fall the harvesters are back inside the nest. But there's still a lot going on out in the desert. There's another ant here, too. The night ant. This is one of their nests in front of me. They normally only come out after dark. And they're generalists - they'll eat pretty well anything, but they have a particular taste for seeds. The trouble is that the harvest ants will have gathered all the seeds during the day, unless the night ants can do something about it. Just after dark, night ants start a major spoiling operation against their rivals. They start to shift stones and fragments of plants to block up some holes near their nest. By morning, it's clear what they've done. They've trapped the harvesters inside their own nests. The harvesters now have a lot of work to do before they can get out to collect seeds. They clear away the rubble as quickly as they can. But this takes time. If they're seriously delayed, the day will be too hot for them to spend time out in the open. So today, they can't collect as much as they normally do. And that means that by nightfall there will still be seeds on the ground for the night ants to collect. Not all ants live in permanent nests. In the tropical forests of Africa and South America, there are some that are nomads. These army ants in the rain forests of Central America are camped in the base of a tree. They've been there for three weeks. During this time, the queen has been laying eggs, several thousand a day. The Army has also been ransacking the surrounding forest for prey, but now it's time for them to find new hunting grounds, so once more, they start to march. The site for the new bivouac has not been picked by the queen, but by the workers. Scouts have been exploring the neighbourhood and they've decided on a new place. And now their chemical trails are leading the whole colony from the old bivouac to the new one. As in an army, the soldiers are prepared to risk their lives for the common good. A group of them interlock their bodies to form a safety barrier that will catch any of their companions that might slip off this sloping trunk. They take everything with them. Larvae, food, and in this case, and very rarely seen, winged males. By the time daylight comes, the Army has established a new bivouac. Its walls and tunnels are formed by the interlinked bodies of hundreds and thousands of individuals. But this is only a temporary count. They still haven't reached fresh hunting grounds. Even so they must eat and the workers set off to find food. There are probably a million individual ants in this one colony. And together they're collaborating and cooperating so that the colony has become one great superorganism. There's no central controlling intelligence as such. Instead, the behaviour of the superorganism is the cumulative result of thousands upon thousands of tiny mini decisions by individual ants. The worker moves forward into new territory, leaving a chemical trail behind it. And then another following in its trail advances still a little further. So the superorganism as a whole is moving through the forest, searching for food. These hunters can subdue almost any other creature in the undergrowth. Some predators may be armed with virulent poisons or their attackers are too small to sting. A lizard has no defence at all. A special caste of workers with particularly large jaws protect the smaller workers as they sting their prey and butcher it. The venom in their stings liquefies the tissues of their victims so that the bodies are more easily cut up into smaller pieces to transport. The chemical trails laid down by the first scouts have now been strengthened and broadened by the passage of many, many more workers. And now those trails are serving as highways along which booty is being brought back to the bivuoac to feed the young brood. Remarkably, almost as soon as these workers return with food, scouts begin to search for a new bivouac site. The colony will move again tonight, and every night for the next few weeks, until the Queen's ready to lay more eggs. When it comes to creating a permanent home for a colony, the champions by far are these tiny critters. Termites. Unlike ants, all termites are vegetarians. They are in fact descended not from wasps, but from cockroaches. And their huge nests act not only as their fortresses, but their food stores. They build with nothing but mud and their own excrement, yet their nests are gigantic. If termites were our size, some of their homes would be four times as tall as New York skyscrapers and measure up to five miles across at their base. These are not quite so tall, but they're particularly remarkable for another reason. Every one of these termite hills points in the same direction, north and south. It's as though they were needles in a compass. And indeed they're called magnetic termites. They in fact take their cue for building from the magnetism of the Earth. But the benefit of doing so comes not from that, but from the daily movement of the sun. In the morning, the rays of the rising sun strike the Eastern face of the mound. Foursquare. And the termites after the cold of the night need warming up and are gathered in galleries immediately below the surface. But as the day continues, it warms up. But the termites don't overheat because the rays of the sun only strike the surface dancingly. And by midday, the full force of the sun is felt only on the top edge. As the sun moves towards the west, so this face becomes roastingly hot. But the eastern face falls into shadow and remains relatively cool. And the termites stay at a temperature that suits them best. Other termites escape the heat of the day by retreating to deep cellars below their mounds. But these magnetic termites colonise areas that flood during the rainy season. And the ground beneath them is regularly waterlogged. So the compass like mounds are a response not just to the movement of the sun, but to badly drained sites. Here in South Africa, it can also get very hot, but there's no danger of flooding. So termites can take refuge from the heat below ground where it's cool and relatively stable. But 2 million insects living below ground create a different kind of problem. The air around them gets stale. So termites need to have a way of linking the underground air with the fresh air above, a ventilation system. And they do that with this. And to see how it works, you've got to look inside. Using the latest scanning techniques, we can create a picture of the mound's interior. An intricate network of passages lead to a central chimney. Hot, stale air from the insect population below rises up through the chimney. But the top of the mound is sealed. So how does the stale air escape? The mound may look as though it has strong defensive walls like a fortress. But in fact that these walls are porous and their primary purpose is to harness the wind. Fresh air blowing against the side of the mound is forced through the tiny holes in these walls. From there, it travels through the smaller tunnels until it reaches the central chimney. Here the cooler fresh air mixes with the hot, stale air rising from the insect community below. Meanwhile, some air is blown around the side of the mound. This creates a suction that pulls the stale air out of the chimney and out through the outer walls. So an internal air currents is created and the whole mound ventilated. The mound's inhabitants spend most of their time close to or below ground level. beneath their living quarters there are garden chambers where the termites cultivate a fungus that rots the wood and vegetation they collect and make it digestible. Farther down still, the queen lies in her own chamber. A huge body is a gigantic egg producing factory. She so swollen that she can't look after herself. The workers must constantly clean her and feed her with food from their own crops. Her partner, with whom she founded the colony maybe 20 years ago, is still with her and mates with her throughout her life. She lays eggs at an extraordinary rate, as many as 30,000 a day. As she produces them, so workers remove them from the royal chamber and take them to nurseries. There, there'll be fed on compost from the fungus gardens, until they turn into adults. The superorganism that lives in this great castle crops the surrounding vegetation just about as severely as an antelope. The density of individual termites around here is extraordinary, over a 100 thousand per square metre. And just as there are lions and leopards that hunt antelope. So in the undergrowth, there are insect hunters which prey on the tiny herbivores. The ants. The termites' ancient enemy. Matabele ants. Specialist termite hunters. A scout has laid down a clear chemical trail and this battalion of workers have picked it up and are following it. There may be only a few 100 of them, but they're going to severely test the defences of a termite colony. The mound has formidable guards - soldier termites. The ants have a special technique for dealing with these soldiers. They grab the termite's jaw and then sting it in the only vulnerable place on its head - in its mouth. The ants' front line breaks into the colony. Reinforcements from the termite soldiers arrive quickly. Already there are casualties on both sides. But the invaders overwhelm the defenders. It's not to the ants advantage to kill an entire termite colony anymore than it would be sensible for farmers to exterminate their cattle. Better to let most survive so that they can be regularly raided. So although there are millions of termites in the colony, the Matabele ants rarely go deep into the nest to press home their victory. The raid lasts less than 15 minutes. Nonetheless, the spoils are impressive. Termite bodies are now being piled in dumps outside the nest. Many of the casualties are still alive but paralysed by the ant stings. Now the raiders have the considerable task of carrying their victims back to their nest. They will have to take all their booty with them. If any termite bodies are left behind, they will be collected by scavengers. The termite soldiers certainly fought hard. One of their dead still grips a Matabele soldier in its jaws, which it killed before it was itself slaughtered. Well, it's been a successful raid. Many of the bigger ones have got mouthfuls of termites. How they managed to hold all of them in one mouthful, I don't know. But obviously, they've got a little way to go now. And soon the young ones back in the nest will be getting good food. The Matabele ants will use their plunder to raise more workers. Ironically, the raid will have the same effect on the termites. The queen will detect the loss of her soldiers and workers and will increase her output of eggs to repopulate the colony. So there will be just as much food for the Matabeles the next time they raid. The tiny creatures of the undergrowth were the first animals of any kind to colonise the land. They established the foundations of the lands' ecosystems. Ultimately, they were able to transcend any limitations of their small size by banding together in huge communities of millions and putting up buildings like this one. If we and the rest of the backboned animals were to disappear overnight, the rest of the world would get on pretty well. But if they were to disappear, the lands' ecosystems would collapse. The soil would lose its fertility. Many of the plants would no longer be pollinated. Lots of animals, amphibians, reptiles, birds, mammals, would have nothing to eat, and our fields and pastures would be covered with dung and carrion. These small creatures are within a few inches of our feet wherever we go on land. But often they're disregarded. We would do very well to remember them.

Life in the Undergrowth

A summer evening on the Körös River in Central Europe. It's waters are mirror smooth. But on this particular day of the year all that is about to change. Giant mayflies, Europe's largest, are starting to rise to the surface and struggle out of the skins in which they lived as larvae. At first, they come in ones and twos. Soon, there will be millions. For two years they've lived under water, now, they must fly to find a mate. This should be the climax of their lives. The first to appear are quickly taken by predators. But soon the swarms are so huge that neither fish nor birds can make any impact on them. The first mayflies to emerge in this mass hatching on this river in Hungary are all males. As soon as they free themselves from the larval skin on the surface, they takeoff and seek safety in the banks. And there they hang in trees and bushes, or indeed on my finger. And the reason they have to rest like this is because they still have to make one final molt. Their wings that were transparent now have a handsome blue tinge and the elegant filaments at the end of their abdomens are even longer than before. They're looking for mates. But they have a problem. They can't feed, for they have neither mouth nor stomach. They have to fuel their flight entirely from the reserves of fat that they built up when they were larvae feeding in the river. But that fat will only last them for about half an hour of flight time. So the race to mate now becomes a frantic one. The females begin to rise to the surface and the males fly up and down the river searching for them. As soon as they find one, they all pounce on her, competing to be the one to fertilise her eggs. But the struggle of doing so saps their limited energy. Before long they begin to run out of fuel. Although they flutter despairingly, they can't maintain themselves in the air. Their lives are almost over and dead bodies start to litter the surface of the water. But the females are still in the air. They're flying upstream. Judging the depth of the river and the currents in it to find a place where they can lay their eggs so that they will float back down river to the same sort of place where the adults themselves lived as larvae. The ancestral mayflies were among the first creatures of any kind to take to the air about 320 million years ago. For them, as for their living descendants, flight was a brief but invaluable way of finding a mate and expanding their breeding territories. The river has also been the home of another kind of insect with an equally ancient ancestry. And it too is beginning to emerge from the water. Bigger and more ferocious than the mayfly larvae. It has been feeding on tadpoles and even small fish. But that phase of its life is over. Now, each one has to haul itself out of the water and into the air. On the top of its thorax, it carries a bulging backpack. It hunches itself and its outer skin splits. A very different creature begins to appear. White threads are drawn out of its fangs. They're the linings of thin tubes that penetrate deep into its body. Air tubes that will enable the insect to breathe now that it is out of water. It gulps air, inflating its body, forcing fluid into the bundle on its back. Its wings begin to unfurl. Ten minutes later, the wings open. They'll never close again. Next, the huge muscles within its thorax must be exercised to prepare them for action. And it's away. Dragonflies, like mayflies, belong to the most ancient group of insects that flew over the land. Here in the museum in Harvard, there are fossils of them that are 150 million years old. They're almost identical with species that are still flying today. However, they are by no means the oldest. We know that there were other dragonflies even earlier, 225 million years ago, that were flying through the Coal Measure swamps. We don't have complete specimens of any of those. But there are some tantalising and amazing fragments. And here's one. This marvellously preserved wing has very much the same pattern of veins supporting panels of membrane as living species. The thing that makes it different is it size. From base to tip, it measures 12 inches, 30 centimetres. Little imagination is needed to replace the membrane that must have been there. This insect must have had a wingspan as big as a seagull's. Vibrating these wings, preparing for flight, must have been a formidable business. A creature this size must have been at least 10 times heavier than the largest insect flying today. How did it manage to get into the air? One suggestion is that in those far off times there was much more oxygen in the air. And that would have given the extra power needed to beat these huge wings. But it's a fair guess that this ancient pioneer of the skies flew with much the same technique as dragonflies do today. Living dragonflies can reach speeds of nearly 40 miles an hour and fly several miles in their search for new territory. They're all aerial hunters, relying on their supreme analytical skills to snatch their prey from the sky. Their great agility in the air comes from being able to beat each of their two pairs of wings quite independently. You can see clearly that they do this when the cameras slows down the action 400 times. This one is coming into its perch. Perfect control is essential to make all the tiny adjustments needed for an accurate pinpoint touchdown. All dragonflies when they perch hold their wings outstretched. But they have close relations, Damselflies, and they perch with their wings closed above their backs. Mosquitoes stand little chance when damsels go hunting. But flight for damsels, as for dragonflies and mayflies, is primarily the means to find a mate and to breed. And to do that, they, like the others, need water. Flight is itself an important element in their courtship. These blue males must first establish the territory for themselves above open water, and that involves aerial jousts that can last for hours. Mature females, whose wings in this species are not blue but golden brown, are attracted to those males who control good places for egg laying. But the males must nonetheless display the correct wing signals. This one, patrolling his territory, is using a special flight to flaunt his handsome wings, inviting females to join him. A female signals her willingness to consider doing so with a flick of her wings. So now he treats her to his full display. The female's tail-up posture is apparently a signal the declares that she's not yet sufficiently impressed. Now it seems he's got it right. Her tail is pointing downwards. He grabs the back of her neck with the claspers at the end of his abdomen. She brings her abdomen forward to reach a chamber under his thorax where he stores his sperm. His first action though, is to scour out her genital tract to remove any sperm that might be there from a previous mating. Only when he's done that, will he inject his own sperm. And now he may show her the best places in his territory for laying eggs. He flies up and down with his tail curled, and lands on a suitable piece of vegetation. The female settles down to lay, cutting slits in the plant stems with her ovipositor and inserting an egg into each one. She may lay as many as 30. And all the time, the male keeps guard, lest rival males should try to mate with her. In other damsel species, the males make sure that no other male can reach their partners by keeping hold of them throughout the whole process. The young that hatch from the eggs of these insects, the larvae, look very unlike their parents. This is a dragonfly larva, and it's in this form that dragonflies spend most of their lives. The larvae of both dragonflies and damselflies are savage predators. They'll even feed on their own kind if they get the chance. This particular larva has a very special problem. It's a cascade down, and it has to snatch prey that is swept past it by the rushing water. Cascade damsels are very rare and live around just a few Central American waterfalls like this one in the mountains of Costa Rica. The adult male has to perform his courtship flight under very difficult conditions indeed. Somehow he's able to fly even when he's dripping wet. And he shows off to the females by actually flying through the cascades of water. To be a good breeding territory, the vertical rock surface has to be covered by just the right amount of water. Too deep, and prey may be out of reach. Too shallow, and the larvae could be picked off by birds. A female will only mate with a male if she approves of his choice of territory. And this one it seems, does. This is it, and she carefully fixes her eggs to the rocks. But not all damsels need great areas of open water for breeding. In the rain forests of Central America, like this one here in Costa Rica, there's a damselfly that has managed to break the link with open expanses of water like rivers and ponds. It's also one of the most spectacular members or the entire family. The helicopter damselfly, the largest in the world, with a wingspan of up to 20 centimetres. The males tend to frequent sunlit patches where the females can see them easily. And they have a special lazy flapping way of flying that is in itself an invitation. But although helicopter damsels can live away from rivers and streams, the females nonetheless require a little water in which to lay their eggs. And there is just enough in this little hollow here. And with luck, she'll come down. And into the water they go. But these eggs have watertight cases so they can be laid in air. They're butterfly eggs. The link with water has been broken. Butterflies fly in a very different way from dragonflies. They overlap their two pairs of wings, so they flap as a single pair. They can't fly as fast or as aerobatically as dragonflies, but they nonetheless are tireless in their search for the particular food that will suit their young. And in the case of the cabbage white, that's cabbage. Now, on the surface of this cabbage leaf, there's a patch of tiny little pill box shaped eggs. And when they hatch, the baby caterpillars will emerge and make an instant meal of the greenery. And they are already stirring. But the first dish on the menu is not vegetables. It's the shells of their own egg capsules, protein-rich, and far too nourishing to be wasted. That first course, however, doesn't last long. Now, for the main dish, cabbage leaves. When cabbage plants are damaged, their leaves release a smell, and that quite often attracts the attention of a rather different insect. It's a tiny wasp called Cotesia. She too is trying to make sure that her young have food immediately available. But they like living flesh. So she injects her eggs into the butterfly's caterpillars. She does this with such surgical precision, that her victims are not mortally injured and they continue feeding as if nothing had happened to them. But now, much of what the caterpillars so laboriously gather goes to nourish the wasp grubs that are developing within them. As the caterpillars grow, they shed their skins. They do so five times until ultimately they are 800 times heavier than they were when they first hatched. This fully grown caterpillar must now find shelter. A strand of silk trails behind it, silk with which it ties itself to a twig. And here, over a couple of days, it changes into a chrysalis. Those caterpillars that were injected by the Cotesia wasp, don't get that chance. The grubs within them are now emerging. They too spin silk which hardens to form a cocoon beneath the caterpillar's empty skin. Inside the wasp grubs are transforming themselves, and two weeks later, out come the adult wasps. A different future awaits the chrysalis. Within its shell and over a similar two weeks, the caterpillar's body has been broken down, and reassembled. And now the adult is ready to emerge. Its wings, like those of a newly emerged dragonfly, need pumping up with liquid. The creature that was once an egg, then a caterpillar, then a chrysalis, has attained its final incarnation. So another generation of cabbage whites set off to find good places for their young. With their fragile looking wings and apparently erratic flight, butterflies might not seem to be the most powerful of fliers. But in fact, they are extremely accomplished aeronauts, and they can fly hundreds of miles if necessary to find the food they need. Some butterflies use the power of flight for another purpose. To escape bad weather. These lush subtropical valleys in southern Taiwan are warm and green all year round. And in winter they're filled by literally millions of butterflies. They've all come from the north of this great island, 500 miles away. For there, the cold weather has killed off the plants on which they fed during the summer. In the mornings, they take off from their roosts and head for the forest canopy to warm themselves in the rays of the rising sun. They have to conserve as much energy as they can, so instead of using their stores of fat to warm themselves, they absorb the sun's heat. There are four species of crow butterflies here, as well as two species of blue tiger butterflies. And all find enough food to sustain themselves in these warm and fertile valleys. Butterflies feed on liquid nectar and the juices of rotting fruit. And to suck it up, they have instead of jaws an extraordinarily long but extremely thin tube. In a newly emerged butterfly, this tube is in two pieces. For it is in fact a highly modified pair of mouthparts. Each half has its own muscles and nerve supply, so that the whole unit is fully movable and controllable. As the young butterfly prepares for adult life, these two sections are zipped together to form a tube like a miniature drinking straw. A special fluid cements the two halves together. The tube is largely made of a material called resilin, which when distorted, springs back to its original shape. In this case, a spiral like a watch spring. When the muscles within it contract, it straightens into a long probe that the butterfly can then insert deep into a flower. Butterflies and moths have the largest of all insect wings, and they're great size means that they can be used very effectively as billboards on which to display patterns proclaiming the species of their owner. The patterns are produced by tiny scales that cover the wings like tiles on a roof. Some have a microscopic structure that refracts the light and gives the wing a brilliant iridescent shimmer. Others contain chemical pigments. With these lovely advertisements, a male butterfly displays to females and warns off rivals. Vivid patterns and bright colours are used to a much lesser degree by moths, for many are only active at night when colours, of course, are not easily seen. Moths also feed primarily on nectar, which they suck up in the same way as butterflies do. But one moth manages to tap a food source no butterfly has yet exploited. It comes from lantern bugs, which feed by drilling into the bark of a tree with their proboscis and sucking out the sap. This contains a little protein which the bug wants, but a lot of sugar, most of which it doesn't want. So it squirts out the sweet excess. And to make sure that this doesn't attract ants that might attack it, it fires the droplets well away from the tree trunk with the tiniest spring loaded spatula at the end of its abdomen. One enterprising species of moth regularly sits behind the bug all night with the curled tip of its proboscis delicately placed in the stream of droplets. As sugar water accumulates, so the moth sucks it up. Most moths, however, feed by the rather more laborious method of flying from flower to flower. A few, the busiest, do so not only at night but during the day as well. These are the hawk moths and there are several species of them gathering nectar from this buddleia bush in the south of France. This hawk moth can fly very fast, indeed, when it wants to, but it can also hover, as it's doing now, to sip nectar from each one of these small flowers. Beating its wings as fast as this, of course, takes a great deal of energy. So these hawk moths have to spend much of their day going from flower to flower, sipping nectar, which is so rich in the carbohydrates they need to power their flight. They have huge forward-pointing eyes that enable them to aim their proboscis with such accuracy that it slips into the exact centre of each tiny flower. With so many minute flowers so closely bunched together, it would be easy for the moth to visit some twice, but that would waste energy. And if we mark each flower as the moth drinks from it, it's clear that the moth, somehow or other, never does this. Hummingbird moths have no difficulty in hovering. Bee hogs, however, have heavier bodies and they sometimes use their legs to help support themselves as they work. Their need to keep drinking is so pressing that a female will continue to do that even when the male with whom she's mating seems to be trying to fly in the opposite direction. The buddleia plant may be a particular favourite of hawk moths, but it is of course a foreigner introduced into our gardens from China in the 19th century. The hawk moths original supplies of nectar came from the flowers of the meadows, and they still feed there alongside many other insects. This is a carpenter bee. Bees also have two pairs of wings, but they're hooked together, so like those of butterflies, they operate as one. Bumble bees have particularly large and heavy bodies and flight for them can be a real effort. That's particularly so in the spring when the mornings are cold and queen bumble bees are just emerging from their winter sleep. It's only a few degrees above freezing, but a queen needs to get started early to look for food. The thick furry hairs on her body help to conserve what heat she manages to generate. At the moment, she's only a few degrees warmer than the surrounding vegetation, as the thermal camera clearly shows. Her body is only marginally more pink than the blue leaves and moss around her. But she has a special way of warming up for flight. She can put her wings out of gear so that without moving them, she can rev up the wing muscles inside. And that raises the temperature within her thorax by 20 degrees centigrade or even more. As the expanding yellow image on the thermal camera indicates. Her body temperature is now over 30 degrees centigrade. At last, she has a chance of lift off. She will now be able to visit the spring flowers while it's still too cold for others to do so. The long trumpets of the daffodils retain heat very well and they're still warm even after their hot-bodied visitors have left. Flies, back in their distant evolutionary past also had two pairs of wings, but their back pair have been reduced to simple, knob-ended rods. These are particularly long on crane flies. They're part of a fly's flight instrumentation. Microscopic sensors on their upper and lower surfaces tell their owner about the air currents around its body and so help in flight control. They start up even before takeoff. Flies are such accomplish fliers that they can land upside down on the ceiling, or in this case, the underside of a twig. Only when you slow down a fly's flight, here by a 100 times, can you fully appreciate what superb control they have. Some species like these long legged flies flaunt their wings in courtship just as damselflies do. These dance flies are voracious hunters. And it's particularly important for them that they perform their dance correctly. If one doesn't get it right, its partner might well eat it. This performance, however, seems to have been up to standard. For hover flies. arguably the most accomplished of all insect aviators. immaculate aerial control is what makes a male attractive to a female. A male lays claim to a mating territory by trying to stay in exactly the same position in space for as long as possible. That's not easy when there are others all around you trying to do precisely the same thing. It might seem that he's absolutely motionless. But in fact, he's having to make continual changes to adjust for slight currents in the air. It's an amazing piece of acrobatics far better than anything that we could do in a helicopter. And it's all done in order to impress the female to show her that he is superb at holding his territory. Having to chase away rivals that come too close is an exhausting business. And when you're trying to maintain your hold on a particular point in midair, even a small midge has to be chased away. After a morning spent doing this, a male hover fly may have lost as much as a third of his body weight. Little wonder that he takes a break at mid day in order to rest and refuel. He dabs up nectar with mouthparts that are shaped like a pad. Having refilled his fuel tank, the male returns to his territory for the afternoon session of hovering in the hope of attracting yet another female and mating with her. Once again, with his superb eyesight, he's ready to spot anything that might wiz by him at high speed that could be a female. And I might just be able to fool him with a pea shooter. Although there may seem to be an extraordinarily large number of different flies in the world, it's actually the beetles that are the most varied of all insect groups. There are 300 thousand species of them. Most find their food by crawling and borrowing on the ground, and to prevent their wings from being damaged in the process, they've turned the front pair into protective shields. Some, like weevils, keep their wing covers permanently closed and before takeoff push their functional wings out of special slits. Ladybirds, like most other beetles, raise their wing covers and hold them clear of the hind wings throughout their flight. The result could hardly be called aerodynamic, and consequently, their flight is rather lumbering. Blister beetles are scarcely any better. When a flight is over, the hind wings have to be packed away beneath the covers, a process that can be so complex that it demands all the skills of a Japanese master of origami. With flight playing a relatively small part in their lives, many beetles have grown very large. This one, the titan beetle that lives in the forest of the Amazon is almost certainly the biggest of all insects. I have to handle hi, with considerable care because those huge mandibles at the front are powerful enough, it's said, to be able to cut straight through a pencil. He can fly, but he can't get into the air from the ground. He's too heavy to do that, so he has to climb trees and launch himself into the air that way. And that's why it's got such powerful legs armed with sharp claws. The titan is now known to be the biggest of all beetles. The champion is seven inches long from the tip of the mandibles to the tip of its abdomen. The larva of this great monster has not yet been found, but it must be at least twice as big as a beetle. A really huge grub. Beetles and many other insects spend so much of their lives as flightless larvae that it'd be more accurate to think of them as creatures of the earth rather than the sky. Flight for them, as it is for the mayflies, is a relatively brief episode at the end of their lives. These cicadas in the Eastern United States spend 17 whole years below ground sucking sap from tree roots. And then within a few days, a whole population emerges. There may be millions of them in a single acre of land. They clamber up the trees whose roots have provided them with sap for all of those 17 years. And here they change into their adult costume. Now they have the wings they need to search for a partner. Empty larval cases cover the tree trunks and the ground beneath. And above, in the branches, the millions have started to sing. The noise is ear splitting. After 17 years of living underground, the cicadas are now approaching the climax of their lives. And for the males, that means this. The call is his way of attracting a female. The females reply with a quite different sound. A click made by flicking her wings. So that's what the males are listening out for. I can imitate the females' wing flip with a snap of my fingers, and that causes them to follow me anywhere because they're so determined to find a female. Now, can I bring you back? How about coming this way? Oh, the noise is awful. Yes, I can hear you. At last, a male find his partner. And as he does so, his call alters He's indicating to her that, after 17 years, the time has come to get down to business. How do these cicadas all emerge, simultaneously, after 17 long years? Well, we know that they can appreciate changes in the contents of tree sap, so they're able to detect the passing of a year. But how do they count up to 17? We have no idea. But even if we did, this surely would remain one of the most astonishing, amazing events in the insect world. And it'll all be over in a couple of weeks for another 17 years.

Insect Flight

Capturing Takeoff and Flying at 3200 FPS 00:03 300 million years ago, before birds, bats, and even pterodactyls 00:07 insects were flying. They were the first animals to lift themselves into the air 00:13 and they're still the most successful flyers on earth. 00:19 i've been putting a bunch of insects on this little platform here and filming 00:22 how they get themselves up into the air and off into their 00:25 flights. I haven't really been doing this for any research purposes, 00:29 i've just been trying to find the most interesting insects I could and film 00:32 them in a way that I don't think anybody else has. 00:35 So, I collected most of the insects in this video by setting up a black light. 00:39 A lot of night-active, flying insects will come to these lights. 00:43 And from this i've been able to collect and film insects from over seven 00:46 different orders. This is the filming set, set up in my 00:49 laundry room. Each of the clips you'll see in this video were filmed here 00:52 at a rate of 3200 frames per second. I specifically avoided filming any 00:58 insects you might have seen flight footage of before. 01:00 So in this video there're no butterflies, there're no bees, 01:03 there's not even a fly. I only went after the weird stuff. 01:07 Like here: this was my half successful attempt at getting a plume moth to fly 01:11 on camera. I couldn't get it to fly in-frame 01:13 without prodding it with a paintbrush. 01:19 These are really unique moths and I love how it just seems to barely be able to 01:23 lift itself into the air. And look at its feather like hind wings! 01:29 I'm gonna have to keep trying to film those moths. They deserve their own video. 01:33 Okay, so let's start with an iconic summertime insect. 01:36 One you've probably seen flying before, but definitely not like this. 01:41 This is the common eastern firefly or lightning bug. Like most beetles getting 01:45 ready to fly, the first step is lifting the hardened, 01:48 protective fore wings that are called 01:52 elytra. One interesting thing that this footage 01:55 shows is that the elytra flap during flight too. 02:01 In getting off the ground, the middle legs are just barely out of the path of 02:04 the wings as they flap nearly 180 degrees around 02:07 the body. The wings actually brush up against each 02:10 other at the top and bottom of the stroke. 02:17 In these scenes the beetles are beating their wings at a frequency of about 62 02:21 full up and down strokes per second. 02:32 This is a painted lichen moth, two flight sequences of the same 02:35 individual, superimposed. 02:43 This might be my new favorite piece of insect footage. The lighting and the slow- 02:47 motion make it almost unreal, like it's animated or made out of clay 02:50 or something. 02:55 One of the things I love in this sequence is seeing how flexible the 02:58 wings are. Here at the end of the downstroke, when 03:00 the wings are turning back into the upstroke, 03:03 the tips of the four wings collapse and roll under the wings. 03:06 They flatten back out as the wings are lifted back up and remain flat for the 03:10 whole downstroke. Some moths, like this leaf roller, get 03:15 into the air by combining the downstroke of their wings with a jump powered by 03:18 the middle and hind legs. Their wingtips also flex and fold at the 03:24 beginning of the upstroke when they're being raised back up. 03:31 Now this is a rosy maple moth. It doesn't jump or roll its wing tips up like those 03:36 others, but honestly who really cares? Just look 03:38 at it. It's clearly the best moth. 03:45 It looks like a flying muppet. Like after it flies off screen here 03:48 it's probably going to go all the way back to living its life on Fraggle Rock. 03:59 Okay, now for some more uncommon stuff. This is a giant stone fly, also known as 04:04 a salmon fly. And look at this thing, it has a 04:06 spectacular jump, absolutely gigantic hind wings, 04:10 and goes straight up and over right into a beautiful swan dive. 04:27 Stoneflies actually have a pretty interesting place in the field of insect 04:30 flight research. Immature stoneflies are aquatic and 04:34 adults hang around the water too. 04:37 Adults of some species are known to use their wings for skimming themselves 04:41 across the water. 04:43 Because the body of the insect is supported by water, surface skimming can 04:47 be achieved with rudimentary wings, ones are actually incapable of powering flight. 04:51 So, surface skimming has been proposed as 04:54 an example of how early insect proto-wings 04:57 might have still benefited the insects even before flight. 05:12 Another aquatic insect is this mayfly. Mayflies are an ancient lineage of 05:16 insects dating back to at least the permian, over 250 million years ago. 05:21 They are different from all the other flying insects in this video in two ways: 05:24 they are unable to fold their wings back over their body, and the muscles that 05:28 power the wings directly attach at the base of the wing. All the other 05:32 insects here flap their wings through indirect muscle movements 05:35 that contract and expand the thorax. Currently, stoneflies and mayflies are 05:41 the source of a debate in the insect fossil record. 05:45 In 2011 a description of this fossil was published. 05:48 It dates back to around 305 million years ago. 05:51 It's the oldest full-body impression of a winged insect. 05:54 The original researchers described it as a mayfly, however 05:57 others have claimed that it actually might better resemble a surface-skimming stonefly. 06:04 This is the biggest insect I filmed, it's 06:09 another one that spends most of its life as an immature aquatic organism. 06:13 This is a fish fly. Right after takeoff this individual is 06:23 flapping its wings at a relatively slow rate of 11 beats per second. 06:27 That's in the frequency range of what a big slow flapping butterfly does. 06:31 And they're usually using their wings to alternate between a powered flight and a glide. 06:51 The fore wing of that fishfly is 37.6 millimeters long. 06:55 That's nearly 10 times bigger than the 4 millimeter long wing 06:58 of the next insect, an aphid. Unlike most of the other insects in this video 07:04 it doesn't seem to jump to get into the air. Wing flapping just kind of picks it 07:08 straight up off the ground. 07:11 The oddest part about this flight is that every upstroke rotates the body 07:15 counterclockwise. Like watch the sequence again and notice 07:18 that on every upstroke the body ratchets backwards, 07:21 like the second hand of a clock in reverse. 07:27 Here're three more sequences, superimposed, in all of them you can see the same 07:31 body rotation on every upstroke of the wing beat. 07:42 This last insect is a scorpion fly. I love how this one gets into the air, 07:46 throws its leg up, and then just turns and kind of stares down the camera. 07:53 That scorpion-like tail means that this individual is a male. Although it kinda 07:57 looks like a stinger, that's actually a mating appendage. 08:04 Isn't slow motion flight footage the best? I'll leave you with one more 08:07 sequence over the credits. This is a green lacewing. This one's 08:10 actually been filmed and studied before, that's why it didn't make the main part 08:13 of this video. Before you go, be sure to subscribe 08:16 to the channel for more videos and thanks for watching this one.

Ganglia

Collections of nerve cell bodies dotted around the insect's body. Being closer means a much shorter distance than going to the brain and back Nerves throughout the entire body

Termites Digest Woods

Digestive system of animals is full of microbes to help us break down food and digest food. Termites rely on their microbes to help digest the food

Insect Sensory Perception

Hide transcript Today's lecture in Insects and the Environment is on Insect Sensory Perception. I'm Brendan Hunt. Sensory perception is essential to informing diverse insect behaviors, like responding to a change in environmental conditions, locating and competing for food, including prey, finding hosts, avoiding predators, and finding mates. As a result, sensory perception has been fine tuned by natural selection. And insects have sophisticated sensory organs. First up is vision. Insect see their environments with compound and simple eyes. In their compound eyes, insects have corneas and lenses, like humans. Light is refracted through the lens into a channel where the photoreceptors are housed. Pigments in the photoreceptors absorb certain wavelengths of light and generate nerve impulses which are sent to the brain. Each ommatidium in the compound eye collects information on a fraction of the image, acting like a pixel. Vision varies greatly among insects, with those that dwell in soil tending to have much poorer vision than those that must navigate on the wing. Each ommatidium generally contains photoreceptor cells that are sensitive to green light, blue light, and UV light in insects. Some species have also evolved photoreceptors sensitive to red light. Bees can perceive UV colors on flowers that humans cannot, as pictured here. Insects may also have one to three of Ocelli, which are simple eyes that detect differences in light intensity, but these are not used for image processing. Stemmata also detect light intensity and are the only visual organs larval holometabolous insects, like caterpillars, possess. These light sensors require minimal processing and are useful for quickly reacting to a stimulus. Insects feel their environments with mechanoreceptors, such as setae and flex receptors. Setae are tactile hairs containing a sensory neuron that fires when moved. Flex receptors are flattened oval discs in the exoskeleton that respond to bending. Clusters of setae are often located behind the head and on legs of an insect. Flex receptors can be found throughout the body. Most insects do not have hearing per se, but can still sense vibrations in the substrate with their setae. But select insects from diverse orders have evolved specialized hearing organs called tympana in order to communicate with members of their species, avoid predators, or detect hosts. And insect tympanum has a similar design to a human ear drum, vibrating in response to sound waves. Insects smell their environments with olfactory sensilla that are primarily located on their antennae. Odorants enter an olfactory sensillum through pores in the cuticle. Odorants or smells are chemical compounds that are often volatile, meaning they vaporize and travel through the air at normal temperatures. And here you can see some sensilla under a scanning electron microscope. Insects have many diverse antennal morphologies. Larger, more intricate antennae provide more olfactory sensilla, which can increase the ability of an insect to detect low concentrations of compounds. Taste operates similar to smell in insects, with specific chemical compounds entering gustatory sensilla and binding to gustatory receptors. The number of gustatory and olfactory receptors an insect has often depends on the breadth of what it eats, with more diverse diets corresponding to higher numbers of receptors for specific types of chemical compounds. Many social insects, like ants, produce odorants in glands in their bodies that act as pheromones. Pheromones are chemicals used for communication with other members of the same species. Pheromones can be used to identify nest mates, recruit nest mates to food, or signal alarm. In this way, many species use chemicals to communicate in their own chemical language. These chemical signals are perceived by sensilla just like other smells and tastes. I hope you enjoy this short video provided on eLC, in which EO Wilson describes how he discovered the chemical language of ants.

Asian Needle ants in the US

Watch video before taking quiz

Spriacles

Where air leaves and enters in incects. Air entering the body passes into tubes (tracheae) divide into smaller and smaller branches

Life In the Undergrowth

You might think that the lights above my head are stars, but they can't be because I'm in a cave. Each one of those tiny lights is produced by the larva of a small insect called a fungus gnat as a way of attracting its prey. The result is a display that must surely rank as one of the most magical illuminations in the whole of the natural world. But shine a light sideways across the ceiling, then you can see that each little blue lamp is surrounded by a curtain of glistening beaded filaments, curtains that are invisible at other times. They're lures, and they can be lethal. Insects hatching in the water below fly up towards these tiny lights. And here they are trapped by threads of this extraordinary material. That is the unique possession of the invertebrates. This is silk. This astonishing cave is near the small town of Waitomo in New Zealand. Each light comes from the back end of a larva as it lies in a transparent tube of mucus slung from the ceiling by silken threads. And it's produced by phosphorescent chemicals in a special compartment, opening from the side of its intestine. The silk comes from glands at the other end, inside the larva's mouth. The larvae move around. They fix a silk thread the rock and slowly inch their way over the ceiling along a network of threads. Arriving in a new position. The larva produces more silk, but this time it allows the thread to dangle downwards. As each section emerges from its mouth, the larva, with a gulp, adds a blob of glue. Eventually, a single strand, maybe a metre long. There can be several hundred larvae in a single square metre of cave roof, and they all work hard, producing strand after strand. The more they make, the greater their chances of catching something. Below, mayfly are hatching from the stream that runs through the cave. They've been carried in here by the current from outside, as larvae. Now they must look for a mate. But they find the blue lights above irresistible. And they're caught. The fungus gnat detects its victim's struggles from lines that run between the threads. Having made a capture, it turns off its light. That saves energy. Laboriously, it makes its way across to the thread from which the vibrations are coming. It holds it up and eats what's hanging on the end. It also eats the filament. That saves silk. This wonderful hunting technique is just one of an enormous number of varied ways in which animals use silk. Silk really is an extraordinary material. It's stronger than a steel thread of the same diameter. And unlike steel, it's elastic. It can stretch up to twice its length. The inhabitants of the undergrowth developed the ability to produce this marvellous material very early in their evolutionary history, over 300 million years ago. At first, it seems, they used it in a very simple way. As an adhesive. And lacewings still do. Though for them it's an adhesive with a difference. This is a female. She is looking for a safe place to deposit her eggs. Silk will provide it, but not exactly in the way you might think. She will lay up to 300 eggs almost twice her body weight. However, there are plenty of other insects around that will eat those eggs if they find them. So she doesn't glue them directly on the plant stem. First, she produces a little drop of sticky silk. And then, at the end of that, the egg. It's suspended safely in midair. Silk is produced by glands in her abdomen in liquid form. It's the very act of pulling it out that changes it from liquid to solid. And that is true for all invertebrate silk. She will lay up to 30 eggs a day, each on its own stalk. That silken thread is so incredibly fine that insect predators like these ants walk right by the eggs without realising that there's a tasty meal within millimetres of them. So despite regular ant patrols in search of food, the lacewing's eggs remain undiscovered. After three days, they begin to hatch. Now, at least, if danger threatens, her offspring will be able to help themselves by running away. In the lush rainforest of Trinidad, you can find sheets of silk wrapped around trees. Here, it's also used for protection. But by a quite different creature in a quite different way. The manufacturers, a little known group of insects called web spinners, live beneath. They graze on algae and lichens hidden by the sheets immediately above them. They produce their silk not from their abdomens or their mouths, but from glands in their forelegs. Each leg has about 150 tiny silk ejectors, which between them create a thin, silken tissue. An ant in search of prey strolls over the surface of the web spinner's Marquis. But the silk sheet, thin though it is, is impervious to smells. And as long as the web spinner doesn't move too much, the ant will be unaware of it, a millimetre beneath its feet. And the tent, like any decent tent, is waterproof. In fact, the tent is so waterproof that the web spinners beneath are in danger of not getting enough water. So after the storm is over, they bite holes in places where a little rain has accumulated, and drink the tiny puddle dry. Of course, the hole has to be repaired after a drink, but that's easy enough when you have an almost limitless supply of silk in your legs. Of all the inhabitants of the undergrowth that have exploited silk, none have done so with more variety and skill than the spiders, and this is almost certainly the first way in which they used it. Here on this bank in the Malaysian rainforest, there are strands of silk radiating from this little patch in the middle. Watch what happens if I touch one of them. I can't help jumping. That was a trap door spider, but it was so swift that you hardly saw it. Let's see if I can get it to do it again. The spider, when hungry, sits close behind the trapdoor. The strands outside are all connected to a silken collar that surrounds the mouth of the hole. Each of her feet is in contact with it. The slightest twitch is enough to tell her that something is moving around outside. A single twitch will produce no reaction. That could be caused by a falling leaf or a drop of water. But a repeated vibration, especially if it moves from one strand to another, could mean prey. Prey like this beetle. Got it. Now it will kill it. This is the most ancient of living spiders. The fact that it has uniquely segmented plates on its back shows that it's more closely related than any other to those pioneer hunters, the scorpions. And like them, it has a powerful venom. Once bitten, its victim has little chance. Trip lines were one of the earliest of the spider's hunting techniques. But other, later spiders use silk to build much more sophisticated structures. Orb webs are so familiar to us that we tend to forget what complex structures they are. A single one can contain up to 60 metres of silk of up to six different kinds, and involve 3000 separate attachments. And what's more, some orb web spiders spin a different one every night. The biggest and best webs are made in most species by the female. She has to start by bridging the gap across which she's to hang her web. The faintest breeze will catch a filament as she spins it, and carry it away into space. With luck, it will catch on a suitable anchor point. There. She runs across the filament, trailing a line of much thicker, stronger silk and ties it off. Then she goes back to the middle of this line and drops down another. And she tightens it. The junction at the top becomes the hub of the web, to which you will attach radiating spokes. These must be particularly strong, for the shape of the whole structure depends on them. Once they're complete, she adds a spiral, working from the middle outwards. This first spiral is quite widely spaced because it's only temporary. It will serve as a scaffolding along which she runs to add a stronger, stickier, and more closely spaced spiral. Perhaps this one. As the filament for this emerges from her spinneret. She coats it with glue from separate glands in her abdomen. After completing one section, she eats the scaffolding line. It has no further use, and it saves valuable silk. At first, this glue is evenly spread. But each time she fixes a section, she twangs it with her leg so that it breaks up and forms a line of droplets. She can complete the whole intricate, elegantly symmetrical structure in about an hour. When an insect strikes the web, the capture spiral stretches and then retracts to its former size without distorting its shape. And without such a severe recoil that the infect might be catapulted off again. The beads of glue are the key. Tension on the surface of a droplet hauls any slack into it. When the insect hits, it pulls out the coils of thread in each droplet, slowing the insect to a momentary standstill. And then the surface tension pulls the silk back into each drop. So the spiral thread doesn't break, and the web as a whole regains its symmetry. The spider sits with her legs resting on the spokes. Any vibration on them will travel up her leg and be received by a small sense organ in the joint. This is covered with microscopic slits, which are distorted by the slightest move, so the spider is immediately aware of the tiniest tremor. Once alerted, she pulls on neighbouring spokes of the web to assess exactly in what direction and how far away the signals originate. The fly is on the verge of breaking loose. Here she comes. She isn't hindered by the glue she put on the capture spiral because her feet are coated with a special oil. Once her victim is in her grasp, she produces yet another kind of silk. It emerges as a sheet from a group of minute spigots. This is a fuzzy silk that's used for wrapping, and at moments like this, as a shroud. The biggest and strongest webs are those made by Nephila, the golden orb web spider of the tropics. They may be several metres across, and they're strong enough to catch small birds. This time only a moth. After a killing bite, she returns to the hub of her web to wrap it up. But big webs bring problems. It's not easy to control what happens on their outer regions. This is Argyrodes. She's only 1/100 weight of Nephila, so she can move across this huge web undetected and she's a thief. A fly has arrived not far from her. She has a chance to steal. But Nephila has also detected its arrival, and claims it without much difficulty. Another fly is caught in the web. Argyrodes now stands a better chance, since Nephila is busy feeding. She cuts the filaments between the fly and Nephila, so that vibrations made by its struggles won't reach her. Nephila, sitting at the hub of the Web, seems quite unaware of what's going on at its outer margin. The fly is now hanging from a single thread, but it's five times the weight of Argyrodes, and too heavy for her to carry. She has to be clever. She attaches a thread to it and runs it up to a twig outside the web. Nephila is still occupied with a meal. Another line, just to make sure. Now she can snip the last filaments of the web and haul it away. Safely off Nephila's web at last, Argyrodes can enjoy her stolen meal in safety. For all its complexity, the orb web was one of the first kind of silken traps devised by spiders. Subsequently, other species modified it in some quite extraordinary ways. There's a web in this yew tree that's triangular. A slice, as it were, from an orb. It's made by Hyptiotes, and her body forms an essential link in its mooring cable. To be effective, the web has to be very taut. Hyptiotes ratchets up the tension by hauling in the main cable and coiling it above her body. Tighter. And that's about as tight as it'll go. Now she has to wait. Flies can sometimes disentangle themselves from a web if the spider doesn't grab them quickly. But a fly hitting this web won't get that chance. A strike triggers an instant reaction in slow motion. You can see what happens. Hyptiotes immediately lets go of the coil she was holding over her back. That causes her web to collapse and almost instantaneously entangle the prey. Few flies that hit a Hyptiotes web manage to escape. The gladiator spider makes her web from a very special kind of multi-strand silk, which she back-combs to make fuzzy. She carefully attaches this to a framework of ordinary unfuzzy filaments. The fuzzy silk doesn't have glue on it, but it will entangle hairy legs. And it's also extremely elastic, which is crucially important. It's finished. She reaches down with her four legs to check how far away she is from the ground. Then she snips most of the framework threads and holds a fuzzy rectangle between her four front legs. She's ready. Her enormous eyes are so sensitive she can hunt in near darkness. A bush cricket would make a rich meal, but it's very powerful, and it could put up a good fight. Now it must be parcelled up, and the fuzzy silk makes excellent wrapping, just as it does for Hyptiotes. In Australia, there is a species of spider that has taken web construction a stage further still. It builds not just in two dimensions, but three. It regularly takes up residence in people's backyards and on their verandas. There's one under this plant holder. It's the notorious and very venomous redback. And what's brought it here is the extraordinary way in which it uses silk. The female usually builds at night and constructs this very elaborate web. It's not just wide, it's deep . To make it, she needs two flat surfaces, one beneath the other. And that's what she's found underneath the plant holder. First she drops down, pulling a thread behind her. She sticks the end to the veranda floor. Then she goes back up again, trailing a second line, which she sticks to the first, so strengthening it. Then she pulls the line tight. That is a crucial element in the construction. Down she goes again. By the time she's finished, she will have fixed several dozen of these sticky taught vertical lines. An ant is approaching in the distance. An orb web would never catch one of these. It's a scout leading an exploring party, searching beneath the plant holder. It's almost bound to blunder into one of the redback's lines. It struggles, and so seals its fate. And its followers go the same way. The threads carry the vibrations back to the redback, waiting above. She has no need to hurry. Her meals are suspended in midair. Escape is impossible. She hauls them up in her own good time. The redback's trap is certainly economical with silk, but one North American spider hunts with just a single filament. This may look like a bird dropping, but that's just a disguise to fool anything that might want to eat it. In fact, it's a spider, and one with an even more extraordinary hunting technique. It's a bolas spider. Throughout the day, she remains motionless, but when evening comes, she prepares for action. She abandons her disguise and starts to move. Slowly, she makes her way down to the underside of the leaf. There she hangs from a horizontal thread. Next she starts to spin a single strong line, pulling it out of her spinneret with her back legs. And at the end there is a sticky globule. This is her bolas. It's all she needs. She climbs back up to her leaf and takes up her position on the horizontal thread with her weighted filament dangling from one of her front legs. A moth. She whirls her bolas, but misses. But she has ways of enticing the moth back. She can produce a pheromone, a chemical perfume that the moth finds irresistible. What is more, she can change it to suit the particular species of moth that happens to be around. The moth comes back. This time she's got it. Now she starts to wrap it. But she's not finished yet. Different moths and a different pheromone. Silk can do other things as well. It can totally change a spider's lifestyle, and turn a solitary killer into a creature that hunts in great packs. This enormous web above me contains thousands of spiders. They're all tiny, but because they work together, they can kill prey many times their own size. Any spider sitting on its web might be expected to react aggressively towards another that approaches it. But not these. These tiny, ant-sized spiders seem totally relaxed in one another's presence. More than that, they cooperate with one another, working together to repair and extend their huge silken palace. There are tens of thousands of them in this one, and they are constantly at work. Their home can rise 15, 20 metres up towards the canopy. It's so big it's a major obstacle in the airways of the forest. This cricket weighs several 100 times as much as one of these spiders. However, the slightest attempt to free itself only serves to attract lots of them from all over the giant web. Soon it's surrounded by hundreds. They squirt glue from their spinnerets, immobilising the cricket limb by limb. They sink their tiny jaws into its most vulnerable places, its joints, and inject their venom. Before long, the cricket is dead and the horde of tiny victors share their vast meal. On occasion, even a solitary spider must meet another spider. Male, after all, must meet female. This is a male Argiope, and he's looking for a mate. But she is huge. 10 times bigger than he is. He has to be very careful if he's not to be mistaken for prey and eaten. Once he reaches her, he starts stroking her body, nibbling her toes. From their taste, he can tell whether the female is a virgin. If she is, she will be less likely to eat him. To confirm that her taste is encouraging, he wipes his feet across his mouth. Apparently he's reassured, for he starts to snip some of the strands of her web to create an open space. He runs a line across it, down towards her. And now he plucks it, like a guitar string. He's doing very well. She's not attacked him, yet. She spreads her eight legs. It's a clear invitation to mate. He checks the taste on his legs again and decides to go further. He pauses. After mating, he has, at best, a 50:50 chance of staying alive. But, nothing ventured, nothing gained. He moves in and delivers his sperm. But his luck runs out. Virgin she may be, but with mating completed, she grabs him and binds him in silk. She will eat him later. Some spiders don't spin webs of any kind, but they still need silk to help them find a mate. And there's one such just here. It's a female wolf spider, a solitary wandering hunter. Like all spiders, she trails a dragline of silk behind her wherever she goes. It's a safety line in case she falls or is blown away, or needs to drop out of sight in a hurry. And here's a male. He's noticed her dragline. The taste of a silk line is very informative for him too, it tells him that it comes from a female, so he follows. His black palps are covered in hairs, which are extremely sensitive. Each hair contains a nerve which can detect even minute quantities of female pheromone. Now he is within sight of her. Being active hunters., wolf spiders have excellent eyesight, so he uses his black palps to send visual signals to her. This display is not slowed down. This is how he does it. It takes a lot of energy, and while he is performing, his heartbeat triples. She encourages him by tapping her legs. He's now within striking distance. The palps he's waving, like those of all male spiders, are loaded with sperm. He leans over, inserts one of them into her abdomen and pumps his sperm into her. Then he does the same with the other. And that's that. At any rate, as far as he is concerned. Three weeks pass and the female's ovaries start to produce eggs. The male's sperm that the female has been holding within her for all this time is now released and fertilises them. At last, she's ready to lay. But she needs a safe place in which to do so. And once again, silk provides a solution to her problems. She starts by spinning a silken sheet stretched between fragments of the leaf litter. She uses that fuzzy silk that comes from multiple nozzles. It will provide a soft padding to protect her eggs. She expels a drop of liquid onto the sheet. Into the liquid, she injects her fertilised eggs. There may be several dozen of them. She checks that the drop has dried. She adds more fuzzy silk to protect it, and it's vulnerable contents, from knocks and bumps. Then she changes silk and starts to spin a tougher kind to cover the whole capsule. She cuts the platform free from its attachments and goes round it, pinching the cut edges firmly together. Finally, she covers the whole parcel with a waterproof silken wrapping. She now carries her precious package with her wherever she goes. She seeks out patches of sunlight so that she can warm it and speed the development of the eggs within. It's a long process that may last several weeks. And then, at last her babies are sufficiently developed to leave their nursery. But even now she doesn't abandon them. They climb up her legs and onto her back. The egg capsule is now empty and can be discarded. And away they go. It's a somewhat rough ride, but the babies, even at this early stage in their lives, know how silk can keep them out of trouble. They use it to tie themselves to their mothers back. And then they use it for yet another purpose and produce it in such abundance that in some seasons of the year it covers great areas of the open countryside. This wonderful, shimmering carpet of gossamer, strands of the finest silk, is the creation of a million baby spiders. It's autumn in England and time for spiderlings to leave their mothers. The youngsters climb up the threads they've spun to reach the topmost twigs of the bushes. They tip their abdomens into the air, and the gentle breeze catches the filaments as they issue from the spinnerets. Some filaments drift down and become entangled in the bushes. But when conditions are right, the threads rise vertically upwards. And away the spiderlings go. On a calm day, they may only travel a few metres, but if there's a breeze, as there is now, they can be swept up, high into the sky. Spiderlings have been recorded thousands of feet up and can travel for hundreds of miles. So, silk can be used for transport as well as looking after the young, courtship, and, of course, catching prey. In an area of heath like this around me, it's been estimated that there's probably 14,000 miles of silk. Enough to stretch from here in England to Australia. Ingenious though we are, we have not yet been able to invent anything as strong, as light, or as elastic as silk.

Darwin's Beatle

whether or not he gets a mate depends on his strength or the size of his jaws

Fire Ants: The Invincible Army

(watch video before completing quiz)- No transcript-write notes here:

The Tiny Beetle is Devastating Forest in the Worse Outbreak

(watch youtube video before taking quiz)

Web of Life- EO Wilson: Of Ants and Men

Bill Finch and EO Wilson are fascinated with the world around them, sparking a 2 decade long friendship Wonders of nature are all around us, over 65 species in their area in Alabama Bama is one of the most biodiverse areas in the world biodiversity was used at first by EO Wilson (one of the first people to use it) There are over 10 million species in the world but scientists are only aware of 2 million, only 20%

Life in the Undergrowth: Intimate Relations

There's an insect in this garden that all gardeners loathe. Aphids. They've made enemies of gardeners, but in the undergrowth, they have friends. Ants. Ants herd aphids to the best possible feeding places. Just as human shepherds will herd their sheep to the best pastures. And just shepherds protect their flocks against wolves, so ants protect the aphids against the insect enemies. Lady birds are among the most dangerous. They after all, eat aphids. So the ants must get rid of them. That's not easy. It's quite hard to get a grip on the polished shell of a ladybug. But eventually, success. Aphids excrete liquid that ants relish. Honeydew. That's why ants protect them. Such close relationships are frequent among insects, perhaps because they've had so long to develop them. They appeared on land after all, about a 100 million years before any backboned animal. And they can also evolve much faster because they can produce several generations within a single year. So perhaps it's not surprising, that have developed relationships between one another of a complexity that blows the mind. These associations extend not only to other insects, but to plants. They were established at a very early period. Plants are the basis of all life. For only they can combine minerals in the ground with gases from the air and produce something worth eating. Insects, however, not only eat them, they also exploit them in much more devious ways. Tropical rain forests are famous for being thick, tangled masses of vegetation. But in this one in Peru, there are mysterious clearings where only one, or at most, two kinds of trees will grow. The local people call such places as this devils gardens and believe that spirits kill other kinds of trees. And the real killers of those trees. Well, they've only just been discovered. The leaves of the surviving trees all have these swellings on their stems. And going in and out are armies of tiny, tiny ants. The swellings are their homes, specially developed for them by the tree, and in them, safe from predators, ants keep their eggs and larvae. They even keep domestic livestock. White scale insects, which like aphids, supply the ants with drinks of honeydew. Producing this accommodation also benefits the tree for the ants provide their landlord with a valuable service. They guard it against its enemies. All kinds of insects will eat a plant's leaves given the chance. But they don't get a chance, not on this tree. So the caterpillar goes elsewhere. This is a more formidable leaf muncher, a kind of giant grasshopper, several thousand times bigger than any individual ant. That was not so easy to shift. But it does have a weak spot. If you can say that any insect has a heel, then this one has an Achilles heel. And the ants seem to know it. Enough is enough. The ants not only repel their host's animal enemies, they also, perhaps more remarkably, keep competing plants at bay. A squad of them leaves the barracks and sets out on one of their regular patrols in the neighbourhood. They found a newly sprouted sapling. Perhaps it's grown from one of their landlord's seeds, in which case, all well and good. But this one hasn't. It's an intruder. They go into action, biting its stems. Reinforcements arrive. Hundreds of tiny jaws cut into its stems. The sapling begins to wilt. But bites alone are not enough for the ants to achieve their ends. They lift their abdomens and inject formic acid into the crippled plant's wounds. The poison spreads through the plant's tissues, hastening its death. And within a few days of being comprehensively stung, all these plants are dead. And the ants, the devils, have extended their garden still further. But the benefit of this drastic gardening, of course, is not restricted to the plants. The ants also profit. They have ensured that their plant landlord can extend its territory without competition. And that provides them with more homes so they too can increase their numbers. It's one thing to provide food and shelter in return for protection. But it's quite another thing to be compelled to provide a home where before there was none. But some insects have the ability to force a plant to do just that. They're called gall makers, and this oak tree is infested with them. This odd wrinkled object at the base of an acorn is known as a knopper gall. Inside there's a tiny grub of a minute wasp. To understand how it got there, we have to go back to last spring. This tiny insect scarcely bigger than the mosquito, is one of these gall wasps. There are lots of them flying around the oak flowers. Most of the flowers by now have been pollinated and are about to develop into acorns. The goal was to have mated, and this female is looking for a place to lay her eggs. She thrust her ovipositor into the base of the fertilised flower and injects an egg. And that triggers a profound genetic change in the growing oak bud. It develops not into an acorn, but into something very different - a gall. Within, the tiny larva whose secretions caused the change feeds on the oak leaves' tissues. As summer proceeds, the galls become increasingly hard and woody. Autumn comes and the oak tree starts to shed its leaves. It's shutting down for the winter. And with its leaves go both acorns and galls. Plant and insect life is suspended. But unseen changes are nevertheless taking place. Spring comes at last. Inside the gall, something starts moving. The larva has turned into an adult wasp. It has spent nine months within the oak tree's tissues. It is only a few weeks of its life left. Now, as an adult, it must look for another oak to inject with eggs. A single oak tree may be afflicted by 70 different kinds of gall, each produced by a different species of wasp, and each with its own particular contorted shape. These hard shells may seem to be effective defences for the little grub inside them, but not necessarily so. This is another kind of gall wasp, and she's not a genetic engineer. She's a burglar. Behind her, she trails her equipment for breaking and entering - a drill. She carefully selects a site for her operations and takes aim. She flicks away the drill sheath and starts work. Her aim has to be very accurate, if she is to strike her target, the larva at the gall centre. The tip of her drill has a sharp cutting edge of metallic zinc, which pierces the gall tissues with ease. When she detects that she's reached the central chamber, a microscopic egg travels down the centre of the drill and into the larva. The operation is over. Her offspring will now hatch in the gall centre, consume the flesh of the resident larva and takeover the gall. Galls are worldwide. California, for example, has other species of oak tree and other kinds of gall. These particular ones are relatively tiny. The size of peppercorns. You'll hardly notice them except for one thing. They jump. And not only do they jump, they jump for three days. The tiny larvae within flip themselves about inside their minute chambers. Why they should do so is not clear. Perhaps it's a way of moving their homes into cracks and crevices where they're out of the reach of predators and parasites and shaded from the hot Californian sun. Another gall in Hungary protects itself in a more complex fashion. It recruits insect gardens. This gall is producing nectar. Sweet. And it's producing it not for the benefit of the oak tree, but for the benefit of a tiny grub that lies within the gall. Because the nectar attracts ants. And ants serve as defenders against any other intruders. And if you want to see how valuable they are... Let me remove some. Within a few minutes, a different kind of gall wasp appears. It's another of those burglars looking for an existing gall into which it can inject its egg. But the ants have now returned. And they attack the intruder. Away it goes. The ants, having driven off the wasp, take their reward of nectar. In the normal course of events, oak trees don't produce nectar, but many plants certainly do. It's a way of attracting insects that will transport their pollen from one plant to another. And the colourful flowers are advertisements proclaiming that nectar is there for the taking. But the plants must also ensure that visiting insects collect the pollen as well as nectar. And that leads to all kinds of complexities. Like many plants, the pyramidal orchid has a way of ensuring that they do. A burnet moth probes into the orchid's nectar store, and as it does so, a horseshoe shaped mass of pollen clips onto its long proboscis. Inconvenient it may be, but the moth can't shift it. Away tt goes to another flower, taking the pollen with it. And this time, as it probes for a drink, a speck of pollen is transferred to the female part of the flower. The job is done. The traffic of insect pollinators to and from flowers is so heavy and in particular so predictable, that it's not surprising that some invertebrates have learned to exploit it. A white crab spider sits almost invisible on a white flower waiting to pounce. And it catches a bee. The spider is clearly taking advantage of the flower's advertising. It looks superbly camouflaged to our eyes, but insect eyes are different to ours and see parts of the light spectrum invisible to us. Under ultraviolet light, we can get a better idea of how they see things. And most surprisingly, the spider looks more obvious to them than it does to us. Why should that be? Perhaps it's because ultraviolet markings on some flowers serve to guide insects to nectar. So maybe the spider's colour is a positive attraction for bees. Certainly, honey bees seem more likely to visit flowers with crab spiders on them than those without, often with fatal consequences. The relationships between the animals that live in the undergrowth are full of such deceits and imposters. Here in Australia, there's an intriguing example that has only just been discovered. This is a feather-legged bug. It too manages to persuade prey to come close. But it's invitations are aimed not at bees, But ants. And what the ants get is a very nasty Surprise. Like all members of the bug family, this one has a long tube for a mouth. Most stick it into plants to suck sap. Using it to eat an ant is more difficult. The bug starts by waving to passing ants. The feathery flanges on its legs are so large they can be seen from quiet a distance. The ants are visibly intrigued. But they're not yet close enough for the bug to attack. So it reinforces its gestures by producing a chemical perfume that the ants find irresistible. They come closer still. They climb all over the bug trying to find the source of this strange compulsive smell. And the bug does nothing to stop them. Where does that smell come from? Is it on the bug's legs? The bug now answers the ants questions. It lifts itself up and reveals a gland on its underside. That's what's producing the smell. The ant presses its head against the bugs chest to actually taste the gland. It's the perfect position for its own execution. The bug stabs its mouth into the back of the ant's head. So a tube can be used to suck nourishment from an insect as well as from a plant. This is the rogue of the bug family. A killer. Ants are among the most numerous, widespread, and frequently exploited members of the undergrowth. These in Australia, collect seeds and store them underground. Plants encourage them to do so by adding a tasty capsule to their seeds. That may seem odd, but these ants don't eat all the seeds they store. In fact, seeds are more likely to germinate below ground than above. But not everything on this forest floor is what it seems. When it comes to putting your eggs in a suitable place. Some insects persuade other insects to do the job for them. This little object looks like a seed, and certainly it's fallen from above. And that ant seems to think it's worth eating. But actually it hasn't come from a plant. It's come from another insect. And this is, it. It's rather difficult to see because it looks exactly like a dried leaf, but it's a stick insect. Its head, antennae, and that's the tip of its abdomen. As an adult like this, it spends all its time up in the trees eating leaves when the time comes today, and this one is day. So all she does is simply to flick away the egg and let it fall to the ground. But that's not quite as risky as you might think. Whenever you are, you can be pretty sure that some amps will turn up looking for food. And that is exactly what the stick insect eggs look like. A nutritious seed complete with that fatty capsule at the tip. So the nth start to hold them away. Although the ants certainly eat a great number of the seeds they store, stick insect eggs. They seem to be quite as tempting at any rate, the amps, after all their labour, usually leave their stick insect eggs untouched. While the seasons pass, the eggs lie underground, hidden from birds and other predators that might eat them. They may remain safe for him to three years. But eventually they tell me at this early stage of its life that a stick and say, actually runs. The youngsters positively scamper up into the tree branches. There they will take up their adult life of leisure. Well camouflaged, standard, they're chewing leaves. Giving your offspring a good start in life can take a lot of effort. So some insects have evolved highly complex strategies to induce other species to become nurse maids on their behalf. This Californian desert heart seems to be the best place to find nurse maids. But blister beetles have an amazing way of discovering them. It starts simply enough with the female beetle. She has dug the hole and is now laying her eggs in it. That done she abandons of a few centimetres below the surface of the sand. Conditions are good for eggs. Not too cold, neither too hot, even in the heat of the day. Six week later, they hatch. But these sums of any burden and scorching hot. Somehow the tiny larvae have got to find food and they weren't find it here. Their survival depends on teamwork. Together. A closely coordinated group. They tie him up a stem of with a glass. When they get to the top, there's nowhere else to go. They look dangerously exposed to the sun and to other predators. But there they stay in a tight, squirming mass. For those that can get there, the top of this stem has become a stage for a remarkable piece of deception. What these larvae want is a lift, a ride. And they want it so badly that sometimes I'll even try and get it from a human finger. But what they're really searching for is not human finger. They're searching for another insect. Eric comes, a female digger be leaving a tunnel that she's just dug fire young. She's off to get the pollen. She packs it into baskets on her back legs and takes it back to her borrow. It will provide valuable food for her young when they eventually hatch. And here comes a male. He's on the lookout for a female. To him. The cluster not only looks like a female, it smells like a female for the beetle larvae are producing a perfume, a pheromone that is exactly like that emitted by a female bee. He a light in order to mate. And in second, this is covered by the larvae that swarm all over him. At first he assumes done by the shock of his sudden increase in weight. But then he's off again. Now his luck improves. This really is a female. And while he made his passengers jump ship. Now they're all on board. A female bee. She having mated, goes back to our nest to lay, taking the larvae with her. At last, the young beetle larvae have reached safety and food, the sort of pollen that the female digger bee worked so hard to connect via own young. So they hop off and tuck in. Not only do they consume the Palmer, when that runs out, they will eat the young bee larvae to blister beetles are not alone and using couriers to take their offspring to food. The young, this butterfly here in Brazil feed on the blood and tissues of living cows. But how is a female to get them there? She is a big insect, same big. The cows would notice if she landed on them and would probably flicker off. She needs a lightweight. Korea's a house fly, a fraction of her weight. Unfortunately, she drops down to store it, manipulates the house, fly into the right position. Now, one by one, she lose her eggs onto the house flies. Within a few seconds, the house fly has been coated by about 30 cream coloured inks. The butterfly releases its hapless messenger. The house fly seems well aware. It's carrying an extra load, but he can't get rid of it. So it goes back to its normal business, which includes visiting cows, drink, sweat. A small fly, unlike the numbering bot fly, is no real irritation and it's able to feed large now unhindered to fly, Mozart sweat with its pad shape mouth bonds. But as it feeds. So the warmth of the cow's body causes the butterfly, thanks to the larvae, are armed with tiny hooks, which helped them to get a grip on account skin and bought into it. So in a few minutes, a car can acquire a dozen bot fly larvae feeding away when he thick skin, licking, get rid of them now, a couple of months later, the foreground larvae emerge and drop to the ground. They were 10 into the soil, pupate and turn into adults. All kinds of creatures, great and small, I exploited by insect parents in this kind of way. This is Costa Rica, and he loves the species of fortune Snyder. They construct horizontal or webs as lovely as those made by any spider. But one individual has a hangout on an anonymous looking one is clinging to our abdomen. She seems little affected by having a passenger. And every day as usual, she builds a new and perfect when she is just as efficient hunter. But every cat she makes, she shares and effect with her passenger. For the gramme is sucking juices. Messenger stays with her for some two weeks, slowly growing in size. Attorney. And still daily, she constructs a new web. Then one evening when as usual she starts to spin, something, seems to have gone dramatically wrong. She seems incapable of making her normal, beautiful orb. What she produces has no shape, no radiating spokes. Name Stick is fine. It's just an untidy tackle. The grub is responsible. It has injected her with the hormone that's spread to her brain and deranged. She has only are now also to live. This is her last act. Small claspers inflate on the gloves back. With these, it grasps the wreckage of the web service will not fall as the dying spider loses her rib and it sucks the remaining fluid from the spider's body. Slowly. The liquid is withdrawn, leaving the spiders legs are emptied until the court says no more than that. The grub has no further use for it. Now the grub clinging to the spiders last tangled web starts to spin for itself. You need to shelter in which to reorganise its body. A cocoon. Inside the lacI walls. Its body is breaking down. Four, it has to be reassemble in a very different thing. At last, the killer is about to reveal its true identity. It's a wasp. Now, it must fly off to find a mate so that another wasp egg may be attached to another orchard spider. The opportunity to find creatures to parasitize in the undercut a seam. Almost endless. And yet surprisingly, there are some parasitic wasps that find their victims in water, in lakes and poems like this one. They're extremely small, about a quarter of a millimetre long. In fact, one of the smallest of all insects. And I've got some in this test tube and give you an idea of just how small they are. Our drop this pin in alongside them, give a sense of scale. Yet these tiny specks have eyes, legs, feelers, just like any other insect. They're known as ferry wasps and spend nearly all their lives underwater. They make a tiny water free itself failure the size of a grain of sand look like a child. They are so minute. They can lay their eggs inside the eggs of other insects, and they choose those laid by water beetles. Water beetles lay their eggs inside plant stems. A female fairly wasp, having located one, uses it microscopically thin ovipositor to inject up to a 100 or so eggs into just one. Because here they hatch. The young wasp feed and grow, consuming the water beetles, undeveloped young. Not only that, they mate here. Then at last they leave the shell or the Beatles egg. The females must now lay and some will be able to do so in other poems because in spite of everything, they still have wings. Other bigger parasitic wasps have totally lost their wings. You can find them on many British he's this one. Methoxy, looks rather like an end. And insects that live by hunting and easily mistake it for once. The tiger beetle is a very active and hunter. It chases them and Bunsen down. And very successful it is earlier and it's life of course, as a larva. A tiger beetle can't run around. Instead, the larva catches ants by waiting an ambush. It plugs the entrance to its burrow with its armoured plate like head. If an ant touches that, just because it's dead. It works every times. Ms. Stacia, however, here's a more awkward. The beetle larva is waiting with jaws agape. That methoxide is more agile than the usual AMD and it manages to slip out between the beetle larva is, it grabs the larva soft body, and now it stings it. But Thatcher times out of the tunnel waiting for the poison to take effect. The sting has only parallelize Ann Arbour and the wasp drag so helpless creature farther down each borough. Now, she lays her eggs onto it to prevent anything interfering with her grab while it saves underground feeding on the parallelized beetle larva. She blocks up the entrance. This is the longest and most laborious part of her motherly duties. But now, without any more work from her, her young will have all the food needs to develop into an adult. Underground nests. So certainly among the best protected of all insect nurseries. And indeed, they are very difficult for peptides to break into. Defend their colonies against intruders with great ferocity. And yet here in this meadow and Central Europe, than our empty nest, intruders live undetected. And this one right here. This is the caterpillar of a blue butterfly. And it lives in this nest, undetected and protected by the ants and fed by them for the last two years. Indeed, it has been so thoroughly accepted by dams that they will try and rescue it in preference to the young of their own queen, as in fact, they're doing right now. But how do these caterpillars get into the ants nest in the first place? How calm blue butterflies begin their courtship in June and July. There is surely one of the lovely site. So the European summer as a flutter and flirt among the flowers. Male and female meat and join. Once they have mated with the female, Al Khan blue must find a change. Here. She lays her eggs. Your caterpillars when they hatch, stay feeding on the junction for a couple of weeks. But eventually they fall to the ground. There are ants everywhere and no matter like this, and they soon find it. It smells just like one of their own larvae. And they start to haul it back to where one of their larvae should be. In enmeshed. Other foragers from the same nest found another. During the next few weeks, as many as half a dozen may be taken back to the nest. Here, their whole down to the nursery chambers and put the damped other eggs and larvae. And because the caterpillars continued to produce a fair amount exactly like that produced by the young. And some cells, they're treated as if they were young adults. Even though they're bigger and a different colour. The caterpillars even mimic a sound the amps make when they beg for food. So workers, due to fully feed an API, you might think that this caterpillar has protected itself very well by receiving these ants. But life and the undergrowth is full of surprises. Newman washed it to like the blue butterfly, wants to get its young into an empty nest, but not nearly as large as it has a more sinister intention. Somehow or other. In the meadow full of empty nest, it can detect which one harbours a butterfly, Canada. And this decides there's one of them once inside the and start to attack it as you might expect. But then the ants behaviour changes. There's pandemonium. The boss has released a fair amount that makes the ants attack one another. With the defenders fighting among themselves. Wasp is able to go deeper into a mass. It's reached the nursery and he'll either caterpillars. Now, they are defenceless. The wasp sets about injecting each of them with an egg. A few hints do their best to prevent this. But there's no real opposition. Most of the amps continue to fight among themselves. The wasp finds a second caterpillar. Another egg is laid. The wasp leaves. With the wasp gone and the aunt common, they slowly returns. The caterpillars are still there, alive and apparently well, and the amps continue to care for them. The caterpillars are fully grown. Each starts to construct the chrysalis, which all butterflies need as a protection while they turn themselves into adults. Each chrysalis is cleaned and protected by the amps as if it were one of their own. Pop. One. Again. Out of it comes, yes, a blue butterfly leaves. It's foster home. Out in the open. It's limp, wins, can expand. And now it's ready to flutter and flirt just as its parents did. And the ends are still bewitched by the traces of pheromone clinging to the empty shell, the butterfly leaves behind. But there are still others in the nest as yet, I'm hatch. And out of this one comes not a butterfly, but a wasp. Hardwired into the microscopic brain of this ordinary looking insect. Or a whole series of skills, sensitivities and reactions that will enable it in its turn to give its own offspring are special start in life. It can detect what the amps themselves find undetectable. It can tell the difference between an ant larva and the butterfly larva. What is more in a meadow of a 100 ants nest, it will be able to find the one that contains the butterfly caterpillar, how it does it. We have no idea. So it seems that among the animals of the undergoes, there are many beneficial partnerships. But exploitation and deception can work just as well.

Lateral Interactions

Today's lecture and insects and the environment is on the topic of Lateral Interactions. I'm Brendan hunt. Last time we learned about interactions between plants and insects, which lie at different trophic levels and can influence each other's abundance, distribution, and evolution. We will learn about other intertrophic interactions in the current module, including mutualism and predation and parasitism. But today, our focus is on lateral interactions which occur among individuals feeding at the same trophic level. And we will primarily focus on competition. Lateral interactions include competition, amensalism, facilitation, and mutualism. And like intertrophic interactions, these lateral intratrophic interactions can affect species abundance, distribution, and community structure. Most insects have a tremendous potential for population increase and the overexploitation of resources. The tussock moth provides an example of a Lepidopteran that can increase in population size, causing widespread defoliation and plant death that can ultimately result in the collapse of the moth population itself. Unless the population is limited by factors like climate and predators, competition for limited resources, such as food, shelter, and egg-laying sites will limit the size of a population. Competition is defined as the exploitation of the same resource, which is limited in supply by two or more organisms of the same species in the case of intra-specific competition, or in different species in the case of interspecific competition, the intensity of competition is dependent on the density of the populations involved. A phenomenon known as density dependence. Competition occurs between organisms that overlap in the use of a limiting resource. And if only one participant in the interaction is harmed, this is known as amensalism. Lateral interactions between, for example, two insect herbivores can be negative, as in the case of competition, where both are negatively affected. And in the case of amensalism, where one suffers from the interaction. Lateral interactions can also be positive, as in the case of commensalism, where one benefits from the interaction. This is also known as facilitation. And in the case of mutualism, both partners benefit. Many mutualisms occur between species at different trophic levels. So we will wait to cover mutualism in the next lecture. Competition can result in different population dynamics over time, dependent on the nature of the competitive interactions. Scramble competition is evident in the tussock moth example, where tree defoliation is followed by population collapse. In scramble competition, resources are overexploited, resulting in high density dependent mortality, population crashes, and unstable population dynamics. In contrast, Contest Competition describes a scenario where some individuals retain access to resources for growth and reproduction while depriving others of them as the population grows toward carrying capacity. This results in a more stable population size than scramble competition. Competition can result between two herbivore consumers species that compete for a common resource. This is known as exploitation competition. But competition can also occur between two prey species to avoid consumption by a shared predator. This is known as apparent competition. This competition can occur directly between species, but competitive effects are also frequently indirect in nature, with the influence of one species on another being mediated by a third species or other external factors. An ecological niche of a species describes its role in the environment or the place in the environment that provides the species with all needed resources. The fundamental niche of species describes its pattern of resource use in the absence of competition, predation, and pathogens. The realized niche is the ecological niche that is actually occupied by a species in the presence of competitors and other species. Competitors, predators and parasites narrow the realized niche. In contrast, positive interactions between species in the form of commensalism and mutualism broaden the realized niche. Mathematical models have been developed describing the adverse effects of two species on each other's population growth. The Lotka-Volterra model of interspecific competition describes the rate of population change based on the size of the population, its growth rate, and how far the current population size is from the carrying capacity. When a population is small relative to the carrying capacity, the population grows exponentially. When the population reaches the carrying capacity, it levels off. Equilibrium is reached at the carrying capacity. And importantly, carrying capacity and growth are each effected by competitor species. The Lotka-Volterra model predicts stable coexistence of two species only when competition within a species is greater than competition between the species. When competition is very high between similar species, they may compete until one species is displaced or excluded from much of its niche space. An example of niche displacement comes from the introduced red imported fire ants species that has displaced the similar native North American fire ants species that previously were found in the Southeast. Differential resource use by two competing species will reduce interspecific competition and increase the potential for species coexistence.

Community Ecology

Today's lecture in insects and the environment is on the topic of Community Ecology. I'm Brendan Hunt. A community refers to a group of species that interact in a given area, which can be represented by a food web. In this food web of arthropods based on collard plants, there are three major guilds of herbivores that are targeted by diverse parasitoids and predators. As a reminder, guilds are groups of species that exploit the same class of resources in the same way. And these guilds define the basic roles that a species plays in that community. The guild concept focuses attention on groups of species that are most likely to compete, interfere, preempt resources, or otherwise interact. A trophic level is the stage in the sequence of feeding interactions moving up the food web, going from primary producers to top carnivores. But how is it that such an intricate community comes into existence? E.O. Wilson's conceptual view of community development over time has four major stages. The first is the non-interactive stage, a time period in which there are many resources and little competition occurs. The second stage is interactive, wherein competitive interactions cause a reduction in the number of coexisting species. The third stage is assortative, in which the species that co-exist most efficiently reach an equilibrium. And the final stage is evolutionary, where over long periods of time, natural selection results in a reduction of negative interactions and enhances positive interactions between species. But what sorts of information informed this model? One source of data useful to understanding the processes and dynamics associated with community establishment and change has been colonization studies. A somewhat controversial series of colonization studies were conducted by defaunation through extermination of life on mangrove islands in the Florida Keys in the 1970s. On four small islands an equilibrium number of species was observed, a number set by the balance of colonization and extinction. and these observed numbers were very close to the number of species present before recolonization, despite being different sets of species. This process is an example of ecological succession. wherein the species present in the landscape progress through time in a predictable way. What is it that regulates the number of species and their abundance in communities? Several hypotheses describe processes that act in concert with one another to shape community dynamics. The resource heterogeneity hypothesis states that more heterogeneous environments provide more resources and ecological niches available for colonization by more species. The resource concentration hypothesis argues that specialized herbivores will increase in population size within concentrated patches of resources when these arise. Because host plants are easier to find in concentrated patches, they provide more resources and less associational resistance is present. The enemy impact hypothesis states that a diverse array of plants in a community will provide natural enemies with plentiful food and suitable habitat, resulting in high populations and suppression of eruptive species. Food webs are complex and interactions that link more than two trophic levels together are known as multitrophic interactions. Among these, tritrophic interactions involve three trophic levels. Many examples of tritrophic interactions exist because plants are intrinsically linked with insect herbivores and their enemies in complex webs that entail both direct and indirect interaction pathways. The linear food chain implied by trophic levels is in reality a simplification that does not capture much of the inherent complexity of real communities. For example, omnivory, developmental shifts in diet, environmentally induced diet variation, and the multitude of species that exhibit direct and indirect interactions with one another cannot be adequately captured by a chain like view. Indirect effects that link non-adjacent trophic levels which can propagate up or down the trophic web are known as trophic cascades. Trophic cascades most commonly describe the indirect positive impacts of enemy species on lower trophic levels, including plant biomass, via the suppression of herbivores. Strong cascading effects are expected when plants are palatable and enemies attack herbivores instead of one another. Trophic cascades are transmitted by changes in whole trophic level biomass as mediated by consumption, and they propagate via linear three-level food chains. I've selected a clip from the documentary 'E.O. Wilson: Of Ants and Men' to accompany this lecture. This video details the colonization studies conducted in the Florida Keys by E.O. Wilson.

Mutualism and Parasitism

Today's lecture in insects and the environment is on the topic of Mutualism and Parasitism. I'm Brendan Hunt. Mutualism is the association of two species in which both species benefit from their relationship. The two species may live in close association through much of their lives, in which case the relationship qualifies as a symbiotic mutualism. For example, termites benefit from gut microbes the can digest cellulose in wood. And the microbes in turn benefit from a suitable living environment in the termite gut. Mutualists maybe obligate, as in the termite example, meaning the mutualism is a necessary association required for the survival and reproduction of a species. Or mutualists may be facultative, meaning the mutualism is not essential for survival and reproduction. Based on ecological criteria, many insect mutualism can be grouped according to whether benefits are nutritional or protective. Some insect nutritional mutualisms result in improved nutritional value of food. These interactions usually occur between an insect and microbes. Other insect nutritional mutualism result in the availability of entirely new resources. These mutualisms describe pollinators and the plants they pollinate, mutualisms where sugar excretions or exchange for protection, and microbes that facilitate digestion of entirely new materials like cellulose. Insect protective mutualism include protected domiciles, like stems are thorns that provide nesting sites in exchange for defense, defense against herbivores by the ants. In contrast, insect induced galls offer no inherent benefit to the plant hosts, so are typically considered parasitic or commensal if the plant's fitness isn't impacted. Insect protective mutualism can offer defense against predators, as in the case of aphids being protected by ants in exchange for honeydew secretions. Note that in this partnership, the benefits to the aphids is protective. The benefit to the ants is nutritional. Specific microbes can also provide defense against infection. For example, by producing an antibiotic compound. Parasitism results in an increase to a parasites fitness at a direct costs to the fitness of a host. The parasite can be defined as an organism living in or on another living organism. The parasite obtains its nutrition from the host organism and causes some degree of measurable damage to the host, making parasites particular, of particular concern to the management of plant and animal health, as in forestry or agriculture. A parasite and host are characterized by durable interactions which occur over the long-term. In contrast, interactions between predator and prey are brief. Most caterpillars qualify as parasites by this criteria because they live and feed on a single host plant. But by this criteria, we would not include mosquitoes even though they feed on blood. This is because the mosquitoes are free living. These interactions are brief. Parasites impact host survival and the distribution, abundance and population dynamics of many species. A parasitoid is an organism that has a free-living adult stage that finds an insect host on or in which it deposits eggs are living larvae, the host dies eventually, as with predation, which differs from typical parasitism. But the death of the host typically occurs over an extended period of time. Parasitoid wasps are a particularly diverse taxon. Among parasitoids, endoparasitoids live within their hosts, whereas ectoparasitoids live on the surface of the host. Many host defenses exist to counter parasites. These include physiological mechanisms like defensive chemicals and the host immune response. Protective traits like hardened cuticle, hairs, or cocoons, and behavioral modifications like evasion, sheltering, aggression, and parental care, as well as protective mutualisms. To learn more about mutualism and parasitism, I've selected two videos to accompany this lecture material. In the first, science journalist Ed Young dives into termite microbe mutualism. In the second, David Attenborough guides us through many remarkable examples of the intimate relationships between species.

Population Ecology

Today's lecture in insects and the environment is on the topic of Population Ecology. I'm Brendan Hunt. Population Ecology provides ways of understanding species in nature and in managed systems that can help predict population trends. This is an exercise useful to management strategies for agricultural pests and viruses alike. Demography is defined as the processes of birth, death, immigration, and emigration that determine the size, fluctuations and age structure of populations. Demography includes the study of the size and density of populations, their growth and decline, and their movements and distributions. Understanding the principles of population growth are fundamental to understanding how a population may be expected to change over time. Exponential growth occurs when a population increases by a constant factor in each generation or time period. If a population increases by a factor of two, that means it doubles in size. Exponential growth models provide an expectation for population growth in the absence of limiting factors. As when resources are unlimited. These models are useful to serve as a null point of comparison to assess how and why a population differs from exponential growth. One factor that causes deviation from exponential growth is cooperation between individuals. For example, cooperation between mates is necessary for sexual reproduction and group formation offers fitness benefits in some species. As a result, low population densities can cause extinction by interfering with the ability of individuals to find social partners. This is known as the Allee effect. Competition within a species, or intra-specific competition, is another factor that causes deviation from exponential growth. Competition increases in line with population density and acts to reduce the rate of population change. When competition increases, logistic population growth emerges with population growth gradually decreasing to zero at the carrying capacity. The term environmental resistance describes the combined effects of factors that reduce growth below the biotic potential, which is another way to describe exponential growth. Environmental resistance arises from competitors, natural enemies, weather, and seasonality. As the population increases, various feedback may change the rate of population growth. Positive density dependence occurs when population growth increases as population density increases. An example of this scenario is a small population that increases slowly until reaching a threshold for cooperation, where finding mates is no longer a limiting process. Negative density dependence occurs when population growth decreases, as population density increases. This negative feedback stabilizes population size at an equilibrium carrying capacity. An example of this scenario is when food becomes limiting as competition increases. In contrast, density independent factors are those that influence population growth that are unrelated to insect density, like weather and climate. Life histories describe the life cycles of individuals of a species from egg through reproduction and death. Life history traits include investment in eggs and parental care, progeny survivorship, investment in dispersal or foraging, the age of reproduction and developmental stage- specific vulnerabilities. Trade-offs and resource allocation occur between growth, reproduction, and dispersal, which are shaped by natural selection. Interestingly, multiple life history strategies can be employed within a single species. For example, many insect species produce winged individuals that maximize reproductive investment, as well as winged individuals that maximize dispersal. As shown here for the pea aphid. Population dynamics can be influenced by numerous factors with complex interactions, all acting in concert to shape population change through time and space. These factors include interactions within and between trophic levels, abiotic factors, and disease. The figure at right shows multiple factors involved with the population dynamics of the beech caterpillar. Metapopulation dynamics are particularly relevant to understanding how populations respond to habitat fragmentation. Metapopulation structure occurs when suitable habitat is patchy over a landscape. And local populations have a risk of extinction. Recolonization is possible. And local population dynamics differ. Groups of populations in a region interact as sources and sinks, providing and receiving colonists and sometimes going extinct. All of this plays a role in dynamics of community ecology, which will be discussed in the next lecture.

Climate Change

Today's lecture in insects and the environment is on the topic of climate change. I'm Brendan Hunt. As a result of increases in global greenhouse gas emissions, global temperatures are rising. Temperatures in the US will continue to rise, but the rises won't be uniform. More winter and spring precipitation is projected for the Northern US, and less is projected for the Southwest US. It is projected that heat waves may be more intense and temperatures on the coldest night of the year will be warmer. There may be an increase in frequency and intensity of extreme precipitation events and droughts are expected to intensify as well. The components of climate change are anticipated to affect all levels of biodiversity from organisms to biomes. Species can respond to climate change challenges by shifting their climactic niche along three non-exclusive axes. Time, as with phonology, space, as with range shifts, expansions and contractions. And self, as with physiology. The response of some species to climate change may constitute an indirect impact on the species that depend on them. Overall, our understanding of the effects of global climate change on biodiversity and its different levels of response is still insufficiently well-developed. Yet it is enough to raise serious concern for the future of bio-diversity. Insects are ectotherms, meaning their heat sources primarily from the environment. The ambient temperature can regulate insect metabolism and physiology. At higher temperatures, insects generally exhibit accelerated metabolism, which can lead to higher consumption, faster growth, and shorter development times. This can lead to population increases and reduce generation times. Warmer winter and early spring tend to enhance insect survival and can cause range expansions. Together, these factors can increase the likelihood of insect population outbreaks. Climate change also affects phenology, the timing of seasonal events in plants and animals. Plants and animals use environmental cues to move through particular life stages. Insect pollinator emergence is often synchronized with flower blooming in spring. Insect herbivore emergences are often synchronized with leaf out in host plants. And many birds time their nesting so that eggs hatch when insects are available to feed nestlings. Phenological mismatches can result when interacting species change the timing of regularly repeated phases in their life cycles at different rates. Mismatches can then occur between flowering and pollinators, plant leaf out and herbivores or predators or parasitoids and their victims. An example of a striking effect of climate change on phenology is exemplified by the mountain pine beetle, a forestry pest species. Climate change has resulted in earlier flight season for the mountain pine beetle and warmer and longer summers. In response, many mountain pine beetles have switched from producing one to two generations of offspring per year. This increased reproduction has resulted in range expansion and increased population density. I hope you enjoy the video I've selected to accompany this lecture, which documents the damage of a pine beetle outbreak.

Oxygen in the air

affects how fast or slow insects grow over time the more oxygen in the air, the bigger the insects can be because they are less constrained by the problem of tubes At lower levels of oxygen, insects are meant to be small Small size is an advantage: the smaller you are, the more nooks and crannies you can find and live in... and hide from predators

All Bugs share the same basic body plan

-A head -Throax -Abdomen -The cuticle covers it all, the outer part of the exoskeleton

The major ecological roles of insects

-include pollination of flowering plants, herbivory, predation and parasitism, decompositon, soil conditioning, and serving as important food source for other animals

Agricultural Entomology

Today's lecture in Insects and the Environment is on the topic of Agricultural Entomology. I'm Brendan Hunt. Agricultural entomology is a field that includes the study of beneficial and pest insects associated with agricultural crops and farm animals. The economic value of honey bees and other insect pollinators for crops is over $29 billion as of 2010. And many crops are dependent on insects for pollination, including apples, almonds, blueberries, cherries, oranges, and squash. Decomposer insects are also beneficial to agriculture, as they help break down organic fertilizers and compost to increase nutrient availability to plants. Biological control describes predation and parasitism of pest insects by other insects. This natural form of agricultural pest control is estimated to have an economic value of over $5.5 billion annually. Arthropods destroy an estimated 18 to 26% of annual crop production worldwide at an estimated annual value of more than $470 billion. But fewer than 1% of insects are agricultural pests. Nevertheless, this equates to around 3500 species that require attention. The insect orders that contain the most agricultural pests are Orthoptera, the grasshoppers, locusts and crickets; Hemiptera, the true bugs; Thysanoptera, the thrips; Coleoptera, the beetles; Lepidoptera, the butterflies and moths; and Diptera, the flies. One common class of agricultural pests are the chewers of leaves. These include grasshoppers and locusts, various caterpillars of butterflies and moths, and beetles. Another common class of agricultural pests are the chewers of roots. These include larvae of beetles and larvae of flies. A third class of agricultural pests are fruit flies, which cause damage to soft skinned fruits such as blueberries and peaches. And a final class of agricultural pests are insects that suck, including various bugs. Some of the insects that feed with sucking mouthparts cause most of their crop damage by serving as vectors of plant viruses. In this case, an insect feeds on an infected plant and spreads the virus when feeding on another plant. Thrips, aphids, whiteflies and plant hoppers are problematic vectors of plant viruses that can cause major losses and crop production yields. There are multiple strategies that can be employed to control insect pests in an agricultural setting. Some of these strategies take direct knowledge of basic insect biology to create traps or interfere with insect development. For example, mating pheromones can be used as a lure for a trap. And the chemical methoprene mimics juvenile hormone, which keeps insects from maturing to adults. The use of insecticides, which are substances that kill insects to control pests, is widespread in agriculture. Insecticides can be natural derivatives of plants, as with nicotine, or they can be synthetic compounds, either based on natural insecticides or entirely novel compounds. Classes of insecticides can be functionally grouped by their mode of action, the target of the chemical that results in insect death. For example, all of these compounds are acetylcholineesterase inhibitors. Conventional use of insecticides greatly increases the profitability of agriculture, with many crops unable to consistently yield profits in their absence. For example, without management, thrips alone could cause over 50 percent reduction in cotton yields. But there are negative effects of insecticide use to consider. Many insecticides are broad spectrum, meaning they kill not only pest species but any other insects around, including beneficial insects. Off target insecticide effects can be reduced. In the case of systemic insecticides like neonicotinoids, because they circulate through plant tissues, directly killing insects that feed on them. But the systemic pesticides also impact beneficial pollinators. And even these can leach into the environment. As detailed by Rachel Carson in Silent Spring, it's important to know about the persistence, toxicity, and bioaccumulation potential of chemicals applied to the environment. For example, the half-life of a chemical in the environment expresses the amount of time it takes for the chemical to break down, which is an important consideration for potential long-term environmental impacts. Another critical consideration to the sustainability of agricultural practices is the evolution of insecticide resistance in populations of insects that are being targeted. Resistance is defined as the change in the sensitivity of an insect population to an insecticide, resulting in the failure of correct application of the insecticide to control the pests. As Rachel Carson wrote in Silent Spring, if Darwin were alive today, the insect world would delight and astounded him with its impressive verification of his theories of survival of the fittest. Under the stress of intensive chemical spraying, the weaker members of the insect populations are being weeded out. Insect resistance is not an uncommon occurrence. Over the past 100 years, over 14 thousand individual cases of the evolution of resistance to insecticides have been documented. Pesticide resistance evolves following the principles of natural selection. In this case, a strong selective pressure is introduced by the application of an insecticide. This represents a struggle to survive for the pest population, greatly reducing survival. But importantly, the insects and the pest population are genetically variable with a large variety of random mutations that primarily have occurred during the replication of DNA. And these genetic variants exist as a pool to select from in the population. This genetic variation by chance give some individuals a higher tolerance of pesticide. And these individuals will produce more offspring than more vulnerable individuals. Following subsequent treatments, a greater proportion of individuals will have some resistance. And natural selection will continue to favor mutations that increases resistance. Without the use of practices to limit the evolution and spread of resistance, insecticides can lose their effectiveness over time, which presents a major long-term challenge to agriculture. One major innovation in insect pest management for many crops was the advent of Bt transgenics. But even this is susceptible to resistance. For some necessary background, consider that Bacillus thuringiensis is a bacterium that provides proteins that kill insects. These compounds have been used as naturally derived insecticides in sprays for over 50 years with two major advantages. First, the Bacillus toxin is quick acting, and second, it is specific to particular orders of insects, meaning it does not harm other insects or other animals. As an example of the engineering of BT transgenic crops, we can look to corn. The Bt toxin is toxic to Lepidoptera and pests like the European corn borer. Researchers were able to introduce the bacterial gene that encodes the Bt toxin into corn, resulting in the production of the toxin by cells of the corn plant itself. This eliminated the need to treat the crops and offered quick acting and effective pest control. Because of these advantages, Bt crops are now heavily used with over 60 percent of corn and cotton in the US coming from plants engineered to produce Bt. This has had large financial and environmental benefits. Insecticide use has gone down dramatically and generalist pest populations have been reduced. But just as with any insecticide, resistance to the Bacillus toxin can evolve in pest populations and has been rising over time. As a result, anti- resistance strategies have been devised to help increase the effectiveness and longevity longevity of existing tools to combat agricultural pests. To combat resistance, it is recommended that BT transgenic crops should produce a high dose of Bt toxin. This is to ensure that there are essentially no survivors to produce offspring. Second, refugia should be provided to Bt susceptible insects by planting some proportion of non Bt plants. This can help prevent genetic resistance from spreading throughout the population. Finally, Plants can be engineered to produce two distinct variants of Bt toxins to decrease the likelihood of resistance to both toxins arising in the same individual. This is similar to a strategy that is employed to prevent the evolution of disease resistance in viruses like HIV, where multiple drugs are combined in cocktails to prevent the evolution of resistance. The advent of insect pest resistance highlights the fact that no single control mechanism provides a silver bullet for long-term success. As a result, integrated pest management plans are necessary to improve pest management, lower costs and reduce risk to people and the environment. And integrated pest management is an important area of research. The first step in integrated pest management is monitoring to assess damage, the causal pest and its abundance. The second step is evaluation to try to determine when action should be taken to avoid crop damage and monetary loss. The third step in integrated pest management comprises preventative measures like crop rotation, selection of pest resistant varieties, the use of cover crops, mulches and row covers, and habitat management to promote beneficial insect predators. There are several strategies used to add vegetation to farms to increase populations of beneficial insects, as shown here. And the final step in integrated pest management is the management itself. To be most effective, one must integrate multiple tactics such as behavioral control, cultural control, biological control, and chemical control. To help guide farmers with their integrated pest management plans, land-grant universities like UGA conduct research on agricultural practices, and extension agents help to communicate guidance on best practices. A final important tool in the pest management arsenal is called sterile insect technique. This involves sterilizing males with radiation or genetic modification that are then released to mate with females to prevent production of offspring. Sterile insect technique involves rearing huge numbers of insects in factories. This has been used in medical entomology to control mosquitoes and also in agricultural entomology to control pests. I selected four videos to accompany this lecture. The first provides an introduction to the philosophy of integrated pest management. The second describes practices to manage insect resistance in Bt crops. The third video is about the debates surrounding use of so-called GMOs or transgenic crops. And the final video describes how genomic technologies are being used to identify invasive fruit flies, track their origin, and develop environmentally friendly approaches to eradicate them.

My Garden of a Thousand Bees

This is Bristol, England. And this is my garden. It's not really that special. We've just let some of the wild back in. But as a wildlife filmmaker, I knew there were revelations here that could be just as amazing as anything I'd ever filmed across the globe. In the spring of 2020, as the country goes into lockdown, outside, the garden is coming alive. Suddenly, there are bees emerging all over it. Just go vroom... But if they're nesting, I can't get near them. I can see these little antennae come up, but they look over. And I'm absolutely still but now I have to go to the focus and as soon as I do that they go down again. Discovering the secret life of bees took me on a journey I was not expecting. Can I 'ave a look? Cripes. For over 30 years I've been filming wild animals all over the world. And all of a sudden I'm locked down at home. My only escape now from the pandemic is in my city garden. And my fascination with the wild bees that live here. Turning my cameras onto my own backyard, is revealing things as spectacular as anything I've ever seen before. Transporting me to another universe. Another dimension of existence. Have I just got pandemic fever or is it just another midlife crisis? I'm too old for a mid-life crisis, it's more of a late life revelation. Bees are fast. You can't film them with ordinary cameras and lenses. If you got something just going like this you don't know how it's doing. You really need fast reflexes. You need equipment that's barely being developed. You have to film everything in slow motion and you have to have the reactions of a hawk. I've probably got reactions as good as a rabbit, maybe not even that good. I'm travelling into a hidden world, but one that exists around us all. Even in a garden like this in the middle of a city, there is an astonishing diversity of bees. If I tell people, Oh yeah, the 60 species of bee in my garden, they go, "really, are you sure?" I go, "yeah, what, more than 60." One of the very first bees out is the hairy-footed flower beee. Check-out its hairy legs. I can get close to film these bees because they fly between the same patches of flowers, scent marking their routes as they go. They're like perfumed bee highways. These bees will just go vroom These, of all the bees, are the most fun to watch because of their shear precision flying, They can literally turn on a six bits in a fraction of a second. They got these funny little beady eyes and they do this really kind of keen hovering and when the female moves they follow her around. And I just love that. In those early weeks. Most of the other bees were not even out yet. Today, the Prime Minister has announced that to save lives and to stop the spread of the virus, we must stay at home. As everyone in the country retreats indoors, on the ground, the garden is coming alive. What most people don't realise is actually bees spend much of their life, not as a lovely bee, flying around in the sun, but in the dark as an egg or sort of maggoty thing in a nest somewhere. Then there's the transformation from a larva into a flying wonder of nature. Metamorphosis. It really is an extraordinary process. It takes 21 days for these domesticated honeybees to make the leap. There are 270 other species of bee in this country. They're the wild bees, very different to the social honey bee that we're all so used to. They mostly live solitary lives and many would have been waiting fully formed throughout the winter. Each species with its own particular time to emerge, coinciding with the flowers it likes the best. In complete darkness, somehow each bee knows which way to head on its journey to reach the light. This is the first time they've seen the world. When the bee comes out of its hole, they sit there and they look out, and they do this with their head. They're doing like a kind of pixel shift thing. That I think what they're trying to do is make a very high resolution image that they will need to remember to return to. Suddenly there were bees emerging all over the garden. It's kicking off all over the place. But this is the challenge. If I want to know more about their lives, somehow, I've got to follow them. This garden in spring is utterly beautiful. I'm amazed that so much diversity can exist in such a small place. It's not really special. We've just let some of the wild back in. We didn't really try very hard to manicure it. Just, a lot of things, we just relaxed about. It's full of weeds basically is what you're saying. There's no such thing as a weed. There's only plants that people don't understand. They're all as beautiful as any kind of tulips or chrysanthemums. Indeed, for me, they're more beautiful because they've been created entirely by the forces of evolution. That is nature. For me, a flower is more beautiful if you could see the bee it was built for actually using it. The flower bees have evolved alongside tubular flowers like these. Not until you have the luxury of having the pictures, in slow motion, in focus, in a way that you can go, "oh, I see, that's what it's doing." I had no idea they had such huge tongues. It really is longer than it's body. As she drinks, she buzzes her wing muscles, dislodging pollen onto her body, which she takes to the next flower. Bees are at the centre of the world's pollination services. They are pollinating the fabric of life. Yet all over the world, bees are declining. We really do need to start taking more notice of them. But opening up the secret life of bees is not as easy as I was expecting. I soon found out that many of the bees really didn't want to be filmed at all. The first month was incredibly frustrating because I had all this extraordinary behavior just going on in front of me that I could see from ten feet away. But as soon as I tried to zoom in on it with a camera, it either stopped, or it flew away. The flower bees kind of accepted me. I mean, it was easy to frighten them off. But some of the other bees, I simply couldn't get near. The furrow bees, if they're nesting, I can't get near them. And it is hilarious to watch them. I can see these little antennae come up and I can see these little eyes come up or they look over. And I'm absolutely still, but now I have to go to the focus. And as soon as I do that they go down again. It can take half a day to get through that process where the bee is saying, okay, it's not going away. I'm hungry, I'm going to do something. I've had plenty of experience filming small animals of all kinds. My last film was about ants with David Attenborough. But wild bees are very different. They are so alert, to get close, I have to invent all kinds of gadgets. This is a lens, it's a super tiny, super wide angle lens, super high-quality. That is the purpose of all of this stuff. In order to get anywhere near the bees, I have to kind of shrink myself down to their size. But I also have to stretch time. Bees live in a completely different dimension. At this scale, we get a fresh view on the physics of bee existence and what it's like to be a creature that weighs a fraction of an ounce, but that can gather over a 100 times its body weight in pollen in just a matter of weeks. This is the bee that everyone said couldn't possibly fly. But of course, she can fly extremely well. You see those wing beats? Above them are mini tornadoes which actually suck her into the air. In this dimension, the sound shifts as well. Listening to bird calls filmed at this speed evokes their dinosaur origins. It is incredible to see how they develop an understanding of their surroundings and how their experience grows. When any of the bees come out, most of them have never even seen a flower before. They don't know what it is. When they discover something like a dandelion, they get plastered in pollen. You only see that on the first days of spring. Shortly after they know that they don't want to get covered in pollen, they either collect it or leave it alone. It seems to me they are learning. But actually for me, the most interesting bit is the males. When they emerge, not only have they not seen flowers, they've never seen a female either. They must have some kind of instinctive urge to look for something that resembles a female. But they're not very good at it yet. They're jumping on flies, they're jumping on leaves, they're jumping on completely different species. of bee. This only happens in the early parts of their lives. But they learn quickly from their mistakes. They only live a week or so, and the race is on to find a mate. I'm not sure I could say that insects were in love, but certainly male bees are in lust. The flower bee males are actually quite good at identifying their females. Even so, he's still not having much luck. I think what his aim is, he wants to jump on her back, and enclose her wings so that she can't fly away. Time after time he fails miserably. She was just foraging quietly on her own. Next thing she knows, she's being slammed from the side by an amorous male and now they're tumbling through the undergrowth. The look of shock, anger, horror, you know, even in a bee with no facial expression, tells me that this isn't good. Now he's just looking at her. Oh, I love you. I do. I love you. I love you. I do. Hunting for females is tiring work. This male is looking for a hole to rest in. But not all the holes are empty. For a few weeks in the year, hungry green fanged spiders, feast on naive flower bee males. Helping to weed out the slow and dimwitted. A bigger threat to most bees in my garden, comes not from spiders, but other bees. Like the sinister looking nomad bee. He was looking for the underground nest of a mining bee. By following her. When the mining be turns, the nomad immediately drops to the ground as if playing dead. When the mining bee thinks the coast is clear, she goes to her burrow. The nomad is watching. As the mining bee leaves, the nomad bee sneaks in to lay her egg in the nest. Where her larva will eat the mining bee egg and feast on her pollen store. No wonder so many of these bees hate being watched. As spring draws to a close, I've already counted over 30 species of bee in the garden. And the variety is, is actually quite mind boggling. From minute yellow face bees to gigantic bumble bees. From shiny sweat bees to harry carder bees. From the good old honey bees to these scissor bees. No bigger than a mosquito. Filming this scale of bee makes a difficult task practically impossible. They block their nests with the tiniest grains of sand. I'm focused on an area that's about that big. You can imagine blinking would make the camera shake. Sometimes you can see the heartbeat going like this as I'm trying to film it. It's a nightmare mate. It's a wool carder bee. The male is a monster. And you can see the female's half the size. This male owns all of these flowers. He'll chase anything that comes into this territory. Bees like this bumblebee are in trouble if one of these guys is around. On his rear-end he's got some really quite vicious looking spikes can inflict serious damage to his enemies. He's a bit like a lion in the sense that he mates with the females whenever he can, he attacks anything that moves in his territory. And in particular, when he meets a male of his own species, there is trouble. He meets the other male and the two of them size each other up. He tries to stab it with his spikes. The interlope was driven off. The only welcome bee in this territory, is a female. The male mates with the same female three or four times in a row. Before they seem to get a sense that they've both done this and they don't need to do it anymore. It does appear as if the male can actually recognise which females he's mated with. He just kind of flies up, has a look, and then flies off. So this is the garden where it all takes place. And this, this bit here is particularly good because it's a really hot corner. And this fence post here is where the scissor bees live. But that's a particularly good place to see them. While the Waitrose house, I bought that in Waitrose, the male leaf cutters and the male mason bees love it for roosting at night. So sometimes you can see them all looking out like they're all tucked up in bed and they're just watching. Waiting for the weather to pick up. So this is the flower bee highway right through here and this is where the males will search for females and the females might be here feeding on the nectar here. If the male comes along and he's like, slams on the brakes, he'll hover, and stare at her in a really appreciative way. I've never ever seen successful mating in this situation, but I have seen them mate on the ground. On his route he also has little sunlit patches of leaves, which the female likes to sit on. The female, there he is. The female, she might just be cleaning pollen off herself or something like that. And then the male comes along. Same process he sees her. He's transfixed. He's like, Oh my God. It's like there's a little dance. He has to kind of hover around her and he'll get closer and closer. He jumps on her and he puts some legs around her. And then basically then he gets up and he has to, he gets his hairy legs out. And he starts waving them around. But in real time it's much faster than that. In slow motion, you can see the tufts on his hairy legs. He has gently, three times, he brushes them on the female's antenna. Then three times he brushes them on the female's antenna. It took me a month to discover what he actually does with those hairy legs during sex. All I knew at the start of that was that the hairs are associated with scent. That's about as much as anybody ever knew. By the start of summer, we seem to have survived the first wave of the pandemic. And us humans were finally being allowed to leave home and re-enter the streets of our city. But I was in far too deep. There is a new wave of bees on its way. Here, the streets of bee city are starting to come alive. Bee city is really just some bits of old wood sort of just along the very back hedge, just above the street. So I had heard that if you could drill some holes in it, bees like that, I don't know, just bees were using it. There seems to be a kind of shortage of accommodation. So I built some more. I thought I'd make a more proper bee Hotel. They're all interested in holes. Holes are their thing. They can't fly past an interesting hole without having a look. They just love it. It's all about the holes. This is where bees create their homes. That's what wild bees do. They lay down a larder of pollen and nectar on which to lay their egg. They make an internal wall seal off the cell, then repeat until the tunnel is full. Yellow face bees are also moving into bee city. They're tiny little things, about five millimetres long. They're so small they're pretty much invisible. Most people just don't even know they're there. They just look like tiny little black flies. You wouldn't know what was going on. These two have made their homes in a side chamber of the bigger hole. And they can join forces to keep guard against their arch nemesis. The wasp. Gasteruption. Gasteruption, well, Gasteruption jaculator. It's an incredible gangly weird thing that hovers in such a way. So it just looks like an alien with a jetpack just kind of hovering around looking for the poor old yellow face bee to zap with its ray gun. It has an incredibly long ovipositor that it uses to lay its eggs in the nest of yellow face bees. Those antennae can detect the scent of the host. A yellow face comes back, sees an intruder and attacks. They've won this small battle, but their problems are far from over. A huge woodcarving leaf cutter bee appears in the old city. It's one of the first of this species I've ever seen. She lands right in the yellow face bee's hole. The yellow face rears up on its hind legs to try and intimidate this giant. The way it was now well and truly blocked to the yellow face's nest. It's tough for the smaller bees, but shows just how ruthless these single mothers need to be. The tunnel definitely now belonged to her. I didn't know at the time, but I would get to know this bee better than any others in the garden. I called her Nikki because she had a nick in her wing. But getting close didn't come easy. I think it's really important to know that the thing that you are filming is the thing that the animal would normally be doing. When the bee's relaxed, it's doing what it wants to do, as opposed to what my presence might be forcing it to do. I really wanted to film leaf cutters because of their amazing nest building behaviour. But it's not as easy to film as I thought. I honestly sat by her first tunnel for like two days. I knew that Niki didn't want anything to do with me because she had absolutely avoided me at all costs. And I got really worried, so I backed off to let her, get on with her life. In bee city, it was easy to get distracted by all kinds of drama. In the distance I could see the fly. The jumping spider comes down again and then he sneaks along. He comes up over again and he looks around and when they do their little looking at the fly, he just gets up there and then a green bottle lands over to the left and he has look at that. That's not it. Fly's doing the grooming because it's a lot of work, all that grooming. The back and the shoulders. And doing the head and the eye. And he gets to a point when he's close enough, I can see that he's put his legs down, ready to jump. He jumps and then it's like, and it all comes to stop exactly where it left off, exactly in focus. Because the spider had laid a silk anchor right there. He's got the fly. It's a bad fly for bees, it's one that lays eggs in bee holes. And so in this case, the spider is a friend of the bees, not an enemy. While I was trying to persuade some furrow bees to let me film them at their nest, I noticed that Nikki had completed that nest literally three metres from me. Without me noticing. Where I'd been waiting for two days, was now a green completed cell. That would have been exactly the behaviour I was trying to film. Now suddenly I had a new opportunity. Nikki was moving to the new builds to make another nest. That was probably a month after she first appeared. After that, she'd pretty much accepted me. There is a moment when she looks me directly in the eye, but not showing fear. She just looks at the camera and then she comes out. She looks around, she looks at all the other things, and she looks at the camera again oh yeah, I think I'll be off foraging now, bye. And off she goes. Finally, Nikki shows me her leaf cutting skills. The reason they cut leaves is to line their wooden tunnel. Making a bee sized cell before smearing with nectar and other stuff. Then they go off to gather pollen to fill it. Leaf cutters use their furry belly to gather pollen. But they're far from cuddly. Unlike honey bees, most of the wild bees have a sting they can reuse. And when hassled, don't hesitate to use it. The feisty leaf cutters also have an armor-like exoskeleton. If this crab spider is to have any chance of a kill, it has to find the soft junction between the head and the body to deliver its venom. A sting in the face does the trick. My relationship with Nicky really seems to be growing. I mean, most people would think that's stupid that a bee and a man could have a relationship. But there's no doubt that we were getting to know each other. I can tell she's looking at me. Does she know these are my eyes? I don't know. I have no idea, but scientists have shown that honey bees can recognise individual people. So wouldn't she? This really is a city of bees. And with ten species living there, I suppose you'd say it was a very multicultural place. Spending this much time in the neighbourhood means I'm even on first-name terms with a few of the residents. The naming just comes to you. So Nicky, I call her Nicky cause she's got a nick in her wing. There's another one who is missing half of one of her antennae. She's called one-tenna. And there are two others. One of them is called the neighbour because she lives right next door to one-tenna. And then there's another one called the late comer because she was the last one to appear. Alongside them there are two mason bees, which are much smaller. One of them lived right next to Niki. I called her Leia, derived from her Latin name Osmia leaiana. I could call her princess Leia, but I just call her Leia. If she's a princess, she has a very small kingdom which is basically three tunnels full of babies that she's made this year. Throughout the city, everyone is hard at work finishing their tunnels. The Mason bees like Leia here don't cut leaves, but chew them into pulp to seal the hole. These red mason bees use mud to seal up their nest. Leaf cutters bring back perfect pieces of circular leaf cut to fit that tunnel. Exactly. When closing a hole Nicky will put literally 40 layers of leaf in there all stacked up, to foil her archenemy, the sharp tail bee. The sharp tail is a cuckoo bee and it specialises in parasitizing leaf cutter nests. The sharp tails are a constant threat. I think in Nicky's mind, maybe 40 layers of protection aren't even enough. She starts going off and looking in other tunnels or underneath the blocks. I thought maybe she's looking for some little bits of rock or something. She comes back with a stick like two inches long and she's flying through the air with a stick. I mean, what is she doing with that? How does the stick compute for her? She's experimenting, thinking it through. Clearly something's going on in her mind here. Remember this is a bee. A moment like that reveals far more than preconceived ideas about what a leaf cutter does. But not as odd as I first thought. This construction of grass stems takes bee architecture to new heights. The red tailed mason bee, nicknamed the tent making bee has solved the problem of cuckoo bees breaking into her nursery. After carefully picking a snail shell, she fills it with both leaf pulp and mud. Like Nicki, every stage of the process involves decisions. She spends a long time positioning the shell into just the right angle on the ground. Even digging it into the soil to hold that position. But that's just the beginning. Next comes a huge undertaking. She gathers hundreds of bits of carefully chosen sticks of grass. To drive the stems into the structure, she vibrates wing muscles, which is why the whole thing hangs together. Over three hours, she assembles a structure more than 20 times her height. Nothing can get into this fortress. Back at bee city, Nikki is getting to the end of her tenure. She's looking a bit ragged now, but she's still working hard on her tunnels. Inside, I could see how neatly she's placed the pollen. And this was white thistle pollen. There were no thistles in my garden. Where was this thistle pollen coming from? I watched Nicki when she left. And I watched the direction she went in. She just kept going up in north westerly direction. So then I looked on a map and I looked at the places that in that line that could possibly have those thistles and I got to place called redland green, where there were thistles there When I looked there was a bee pretty much identical to Nikki. I was absolutely sure that was Nikki. When she flies out of her hole she has a mental map of the city. She goes to a place, she has pre visualised. She is going to go to that destination and do the thing that she has planned to do. She has a complex world to deal with. Has to deal with mating, courtship, finding a home, she has to forage. Go great distances. She has to do this all on her own. She can't just ask her mates, Have you seen any good flowers recently, mate? And that I find is a remarkable thing. The more I became absorbed in their lives, the more I was seeing differences in how individuals react to each other. One-tenna is particularly aggressive to everyone. She always seems to be arguing with her mason bee neighbour. They seem to have a sort of tit for tat fighting thing going on. Nikki and her neighbour Leia just get along fine. They never argue. One-tenna, possibly because the antennae are linked to memory through scent came back, but instead of going to her hole, she went to the neighbour's hole. She's got the neighbour's jaws in her jaws. She's trying to pull the neighbor out of her hole. This fight went on and on and on and I mean, I was really worried, I didn't know what to do. I thought what should I break it up? You can't just interfere with things like that. It's never that simple. But I really did want it to stop. These bees were clearly using huge amounts of energy. That story tells me that these bees, they're not all identical. All of them behave differently. They must have some serious brainpower. People would say, Oh yeah, it's just instinct. Well, yeah. But how does the instinct work? Oh, it's an algorithm, mate. Well, how is that different to what we do? It's really hard to explain, but I really feel for them. They really, I could say that they're my friends, I mean, they don't really give me much. Every now and again, one bee or other might actually land on the camera and I do feel touched by that. I felt I knew Nikki pretty well by now. But I wasn't ready for what she let me see next. She is well on the way to filling another tunnel for the next generation. She then does this extraordinary thing. She turns around in the tunnel, something I've never seen her do. So she has to kind of form a ball with a body. Like you've got a gymnast doing some kind of strange move. And then when I pull focus into the hole, I could see an egg. A great big egg, it's huge. I mean, it's like three or four millimetres long. I honestly never expected to be able to see an egg from the outside in that way. What a privilege to be there, at that moment. I have been sitting here for a couple of months but feels like a lifetime, of course not for me, but it is for a bee. I've seen Nikki make three complete tunnels, each with at least six cells inside. And now she's on her fourth tunnel. But it wasn't just me taking an interest in Nicky's new egg. Nicky was by this time very tired and she was just sitting on a brick, just a foot away. As the sharp tail bee went in, I was willing her, Nicky, Nicky, come up, get in your hole. But, um, she didn't. You can tell if a sharp tail bee has been successful, because she'll come out with some pollen stuck to her tail. Nicky went in. It's possible that she went in, saw that it had been parasitized and thought, ah, what the hell. She'd had a very successful nest building life. So I didn't worry about her legacy. She had a good legacy. And that actually was pretty much the last time I saw her. After she left, I actually noticed that I missed her. I had no idea I was going to get so involved, If that's the word, with an individual insect. It's changed my view of insects altogether. It's changed my view of the world altogether. To learn more about what you've seen on this nature programme, visit PBS.org.

Ants

great survival technique ants are farmers... they feeds fungus with grass and feed on the fungus they construct their colonies so fresh air to get in so the fugus won't kill them with carbon dioxide release

Most insects

Has a basic set of biting and chewing tools Bites from ants can be used as defense mechanisms to protect themselves Most powerful weapon is the sting: only 5% of insects have stings... ants, bees, and wasp Venom causes painful stings Tranchlaa hawk wasp: sting is so powerful that it immobilizes tranchalas in the desert

Predator-Prey Interactions

Hide transcript Today's lecture in insects and the environment is on the topic of Predator-Prey Interactions. I'm Brendan Hunt. Predation can be viewed as the consumption of one living organism, the prey, by another living organism, the predator. Predators can dramatically affect the abundance and distribution of prey populations and biological communities. The diverse feeding habits of predators form linkages that are responsible for the flow of energy through food webs. Generalist predators that feed from multiple trophic levels are more accurately described as omnivores. Insect predators use chewing or sucking to ingest their prey. And examples from diverse groups include assassin bugs, dragonflies, mantises, beetles, and lacewings. How is it that predators and prey interact to affect each other's long-term interactions and population dynamics? It is intuitive to understand that predators can suppress prey populations through prey consumption. But predators in turn respond to changes in prey density. These responses can be functional, by causing a predator's rate of prey consumption to change. Or they can be numerical, by causing a change in the predator population size. Indeed, predators and prey exhibit influences on each other's long-term population dynamics. And such dynamics have been modeled mathematically to provide theoretical expectations that can be used as a point of comparison for observed data. There are three major types of functional responses by predators, wherein they change their rates of prey consumption. In a type one functional response, the consumption rate of a single predator is limited only by prey density. Examples include filter feeders and web building spiders. In a type 2 functional response, the fraction of total prey that are captured decreases with increasing prey density. This is the expectation for most insect predators. In a type three functional response, the consumption rate of the predator response slowly to increases in prey density when the prey are scarce, but more quickly when the prey density rises above a threshold. This can result from learning or prey switching behaviors. And a type III functional response helps to promote population stability. In terms of changes in population sizes, most predators increase in numbers as the density of prey increases due to predator aggregation and enhanced reproduction. Aggregation is a behavioral response that results in predator density increases on a short timescale. Over longer timescales, high prey densities result in increased reproduction of predators. This response of predator population size to prey population size can result in cyclical dynamics of predator prey interactions. A prey population will increase when predation is low, which in turn causes predators to increase in numbers. This in turn results in a decrease in the prey population and so forth. Persistent predator prey oscillations are captured by Lotka-Volterra predator-prey equations as plotted in the graph at top right. Real data is plotted in the graph at bottom right, showing that an increase in the density of a prey beetle species resulted in a subsequent increase in the density of a predator beetle species. And this large predator population then drove down the prey population size and began to shrink as a result. However, lab experiments and models incorporating increase biological complexity often fail to reproduce persistent oscillations in predator and prey populations. Because the populations become unstable and extinction of species results. Several factors can help promote the stable coexistence of predators and prey, including habitat complexity, which provides refuge for the prey, immigration, and type three functional responses. In an experiment conducted in the 1950s, it was shown that predatory mites drove herbivorous mites to extinction in the absence of refuge for the prey. But in a more complex habitat, persistent oscillations and relatively stable coexistence of the predator and prey species was observed. Important interactions occur not only between prey and predator species but between species of predators themselves. Predator effects on one another are considered additive if prey depletion by a multiple predator assemblage can be predicted by summing the number of prey consumed by each species separately. But this is not always the case. The presence of multiple predator and prey species in a system can alter their interactions in unanticipated ways. Predator effects are considered antagonistic if prey are eaten less than predicted by summing the number of prey consumed by each species separately. And predator effects are synergistic if prey are eaten more than predicted. When the effects of multiple predator species are additive, this is most commonly a result of resource partitioning, which occurs when different species attack different subsets of prey. In the figure at right, the grasshopper occupies the vertical rectangle. Spider one resides in the upper canopy. Spider two resides in the middle canopy, and spider three resides in the lower canopy. These species hunt in different microhabitats and do not directly impact each other, which results in an additive impact on the prey population in question. Antagonistic interactions among predators occur when one predator species disrupts the ability of another to capture and consume prey. This often results from predators killing one another, known as intraguild predation, or from being displaced from prime foraging locations by one another. Synergistic interactions among predators result from predator predator facilitation, where one species enables another to capture and consume more prey. This often involves conflicting behavioral responses of prey to multiple predators, resulting in prey escaping one predator only to fall victim to another. A graph of such an example is plotted here, where the presence of two different predator species resulted in more aphid prey consumption than would be expected from the individual impact of each predator species in the absence of the other. Predation has had a profound impact on the evolution of prey species, where defensive strategies that increase the odds of survival have arisen over vast periods of evolutionary time. These relate to the non- consumptive impacts of predators on prey traits wherein defensive strategies offer a competitive advantage to the prey that utilize them. Such traits can be induced, but even in that case, the prey must have evolved the capacity for defense induction by predator presence. And prey species have evolved a wide range of defenses and response to selection from predation. These include primary defenses that deter detection of prey, secondary defenses that operate during prey capture, and tertiary defenses that operate during prey handling by a predator. Primary prey defenses prevent the initiation of a capture attempt by a predator, typically by evading detection. These include a wide variety of behavioral and morphological traits. Crypsis is often employed where a color pattern or shape allows an organism to blend in with its environment. In eucrypsis, an organism blends into its background. In mimesis, an organism resembles inedible features of the environment and in aposemitism, an organism advertises its unsuitability to predators using conspicuous coloration, sounds, or smells. Here are two species that have perfected eucrypsis to blend into a background of lichen. Examples of mimesis include insects that mimic bird poop, sticks and thorns. And in Mullerian mimicry, convergent warning colors have evolved to signal unpalatability to predators. Bright red, yellow, or orange colors are often paired with black in Mullerian mimics. As shown here for various butterflies and a bug, Are just such features. All of these species are signaling that they're actually not palatable to a predator. Batesian mimics have taken advantage of such warning coloration to suggest that they are also unpalatable or harmful. Even though this is not actually the case. Here we see a fly mimicking a bee or wasp and a caterpillar mimicking a snake. Secondary prey defenses deter capture more directly, often including behaviors that provide escape or evasion or protective body surfaces like hardened exoskeletons or hairs. Data are shown at left from an experiment that tested the removal of elytra, the hardened outer wings of a beetle, and the presence of a spider predator. This experiment demonstrates the protective value of a hardened exoskeleton. Tertiary prey defenses interrupt predation after capture and during handling. These include mechanisms that deter repel or even kill the predator, such as toxins, venom, and spines. Bombardier beetles provide a dramatic example of a chemical tertiary defense against predators. In reality, it is often difficult to differentiate primary, secondary and tertiary defenses as warning coloration of aposematic prey serve as primary defenses, but are only successful because they usually signal underlying tertiary defenses like toxins. I selected a video to accompany this lecture, where a PhD student discusses adaptations of tiger beetles that help them operate as effective predators, but also adaptations that help them avoid predation by other species.

Areial environments

Insects can be found collecting food as when predating on other insects or visiting flowers

Terrestrial Environments

Insects can be found in soil, plants, decaying organic matter, etc....

Invasive Species

Today's lecture in insects and the environment is on the topic of climate change. I'm Brendan Hunt. As a result of increases in global greenhouse gas emissions, global temperatures are rising. Temperatures in the US will continue to rise, but the rises won't be uniform. More winter and spring precipitation is projected for the Northern US, and less is projected for the Southwest US. It is projected that heat waves may be more intense and temperatures on the coldest night of the year will be warmer. There may be an increase in frequency and intensity of extreme precipitation events and droughts are expected to intensify as well. The components of climate change are anticipated to affect all levels of biodiversity from organisms to biomes. Species can respond to climate change challenges by shifting their climactic niche along three non-exclusive axes. Time, as with phonology, space, as with range shifts, expansions and contractions. And self, as with physiology. The response of some species to climate change may constitute an indirect impact on the species that depend on them. Overall, our understanding of the effects of global climate change on biodiversity and its different levels of response is still insufficiently well-developed. Yet it is enough to raise serious concern for the future of bio-diversity. Insects are ectotherms, meaning their heat sources primarily from the environment. The ambient temperature can regulate insect metabolism and physiology. At higher temperatures, insects generally exhibit accelerated metabolism, which can lead to higher consumption, faster growth, and shorter development times. This can lead to population increases and reduce generation times. Warmer winter and early spring tend to enhance insect survival and can cause range expansions. Together, these factors can increase the likelihood of insect population outbreaks. Climate change also affects phenology, the timing of seasonal events in plants and animals. Plants and animals use environmental cues to move through particular life stages. Insect pollinator emergence is often synchronized with flower blooming in spring. Insect herbivore emergences are often synchronized with leaf out in host plants. And many birds time their nesting so that eggs hatch when insects are available to feed nestlings. Phenological mismatches can result when interacting species change the timing of regularly repeated phases in their life cycles at different rates. Mismatches can then occur between flowering and pollinators, plant leaf out and herbivores or predators or parasitoids and their victims. An example of a striking effect of climate change on phenology is exemplified by the mountain pine beetle, a forestry pest species. Climate change has resulted in earlier flight season for the mountain pine beetle and warmer and longer summers. In response, many mountain pine beetles have switched from producing one to two generations of offspring per year. This increased reproduction has resulted in range expansion and increased population density. I hope you enjoy the video I've selected to accompany this lecture, which documents the damage of a pine beetle outbreak.

Conservation

Today's lecture in insects and the environment is on the topic of conservation. I'm Brendan Hunt. Insects comprise much of the animal biomass linking primary producers and consumers, as well as higher level consumers in freshwater and terrestrial food webs. Situated at the nexus of many trophic links, many numerically abundant insects provide ecosystem services upon which humans depend. The pollination of fruits, vegetables, and nuts, the biological control of weeds, agricultural pests, disease vectors and other organisms that compete with humans or threaten their quality of life, and the macro decomposition of leaves and wood and removal of dung and carrion, which contribute to nutrient cycling, soil formation and water for purification. As a result, severe insect declines can potentially have global ecological and economic consequences. Anthropogenic or human caused factors are causing the extinction and decline of many species. Terrestrial vertebrate population sizes and ranges have contracted by 1 third. And many mammals have experienced range declines of at least 80 percent over the last century. Although a flurry of reports has drawn attention to declines in insect abundance, biomass, species richness, and range sizes, whether the rates of declines for insects are on par with or exceed those for other groups, remains unknown. Although some studies and media reports have declared that the insect apocalypse is here, the reality may be far more complex. There are still too little data to know how the steep insect declines reported for areas of high human activity compared to population trends in sparsely populated regions and wild lands. But reported rates of annual decline and abundance frequently fall around one to 2%. Rates of decline are highly variable. And notably, not all insects are declining. Numerous temperate insects have increased in abundance and expanded their ranges in response to warming global temperatures. Assessment of long-term ecological research sites in the United States suggests that overall insect abundance and diversity are not declining at such sites. However, an important limitation of assessments based on long-term monitoring data are that they come from locations that have remained largely intact for the duration of the study, and do not directly reflect population losses caused by the degradation or elimination of a specific monitoring site. Surely the greatest threat of the Anthropocene is exactly this. The incremental loss of populations due to human activities. Such subtractions commonly go uncounted and multidecadal studies. In areas of high human activity where insect declines are most conspicuous, multiple stressors occur simultaneously. The principal stressors are land use change, especially deforestation, climate change, agriculture, introduced species, nitrification and pollution. There are growing numbers of community science and education initiatives to survey, conserve, and raise awareness of insects and their importance as pollinators, prey, nutrient recyclers, and focal organisms in science and technology, as well as in art, literature and other aspects of culture. In the future, many of the richest sources of occurrence data for insects will derive from community science efforts. If the growth of iNaturalist continues at its present rate, the amount of species level occurrence data for visually identifiable insects will soon surpass that of any other single source. Even without much needed monitoring and demographic data, enough is already known based on first principles and records for various amphibians, birds, flowering plants, mammals, reptiles, insects and other taxa to understand that there is a biodiversity crisis which is accelerating as the planet's human population grows, increasingly exacerbated by unprecedented recent climate changes and other anthropogenic stressors. 70 international scientists recently formulated a roadmap for insect conservation and recovery. Immediate action suggested include a variety of actions like education initiatives, landscape usage improvements, reducing pollutants, limiting species introductions, and enhancing restoration and conservation programs. They also recommend prioritization of species, areas, and issues to target for conservation. In the midterm, the scientists recommend conducting new research to disentangle the contributions of distinct stressors to insect declines and to perform meta-analyses on current data on insect biodiversity as a baseline for comparison in future studies. In the long-term, public-private partnerships and other financing initiatives can help restore and protect vital insect habitats. Standardized long-term monitoring programs should be established through the International Union for Conservation of Nature or the United Nations. For a more comprehensive description of the state of knowledge on global threats to insects, read the article, Insect decline in the Anthropocene: Death by a thousand cuts, which you'll find on ELC.

Animals make up

.5% of the earth's total biomas

Natural Selection Video Transcript

Hide transcript Today's lecture in Insects and the Environment is on the topic of natural selection. I'm Brendan Hunt. In the last course module, we learned about the remarkable diversity of insect groups that exist on the planet. But what evolutionary process cause this diversity to arise? To find our answer, we can look first to domesticated species like dogs and their highly diverse features, or to crop plants. Many of the plants we farm arose from selective breeding for desirable traits over many generations. For example, cabbage, broccoli, and Brussel's sprouts are all derived from a wild cabbage species. This selective breeding by humans is also known as artificial selection. In the natural world, diverse species have arisen from the process of descent with modification as shaped by natural selection. A key ingredient necessary for natural selection to give rise to such diverse life forms is time. A whole lot of time. In fact, the split of what would become vertebrate and invertebrate animal lineages is estimated to have occurred around 500 million years ago. Over such long periods of time. Homologous structures inherited from a common ancestor can be modified in different ways in different groups of organisms to achieve different ends. Here we see homologous bone structures in mammals that have been modified to grasp, dig, run, swim, and fly in different species. Such changes occur over many, many generations in response to ongoing natural selection in different populations, or groups of individuals. So how and when does natural selection result in evolution? Let's focus on one trait as an example. Imagine variation in color that affects the visibility of an animal to a predator. For natural selection to operate on this trait, first, the individuals within a population must vary in the trait. Second, the differences in the trait must be passed from parents to offspring. That is, the trait must be heritable. Third, the individuals must exhibit differences in their ability to survive and reproduce. And finally, this variation in reproductive success must be at least partially due to the trait they have inherited and will in turn pass to their offspring. Here's a graphical representation of the scenario I just described. In this case, we have a population of mice that vary in coat color. Importantly, this variation in coat color is inherited. Another key element is that more individuals are born than will survive to reproduce. In this circumstance, reproductive success will be highly variable among individuals. Individuals with specific coat colors survive and reproduce at higher rates than others because they are better camouflaged from predators. If the mice live on light colored sand, those mice with brown coats will be at a higher risk of predation. As a consequence, the composition of coat colors in the population changes from one generation to the next. This process is known as natural selection. A similar real life example comes from peppered moths, a species with light and dark colored morphs. The industrial revolution in 19th century England resulted in a major increase in soot, which killed lichen on trees and darkened many surfaces. As a result of this environmental change, dark coloration resulted in better camouflage and increased fitness relative to light coloration. By the 1950s, 90 percent of peppered moths were dark in the affected region. But once air quality started to improve in the 1970s, light coloration started to once again offer effective camouflage. And now over 90 percent of the peppered moth population is light-colored. To summarize, through natural selection, heritable traits that lead to survival and abundant reproduction spread in populations. Whereas heritable traits that lead to reproductive failure decrease in frequency and may ultimately disappear. Natural selection is thus an automatic consequence of heritable differences in replication. But bear in mind that natural selection is a statistical process. Although individuals survive and reproduce, it is not the individuals themselves that are evolving. Instead, evolutionary change occurs at the level of the population. The composition of the group members change over generations. That said, the relative ability of an individual to survive and reproduce can be quantified. And this is known as an individual's fitness. How does natural selection explain the origin of species? Watch 'The Making of a Theory: Darwin, Wallace, and Natural Selection' for more on the natural origin of species and to learn how the theory of evolution by natural selection was originally conceived.

Vector-Borne Diseases

Key facts Vector-borne diseases account for more than 17% of all infectious diseases, causing more than 700 000 deaths annually. They can be caused by either parasites, bacteria or viruses. Malaria is a parasitic infection transmitted by Anopheline mosquitoes. It causes an estimated 219 million cases globally, and results in more than 400,000 deaths every year. Most of the deaths occur in children under the age of 5 years. Dengue is the most prevalent viral infection transmitted by Aedes mosquitoes. More than 3.9 billion people in over 129 countries are at risk of contracting dengue, with an estimated 96 million symptomatic cases and an estimated 40,000 deaths every year. Other viral diseases transmitted by vectors include chikungunya fever, Zika virus fever, yellow fever, West Nile fever, Japanese encephalitis (all transmitted by mosquitoes), tick-borne encephalitis (transmitted by ticks). Many of vector-borne diseases are preventable, through protective measures, and community mobilisation. Vectors Vectors are living organisms that can transmit infectious pathogens between humans, or from animals to humans. Many of these vectors are bloodsucking insects, which ingest disease-producing microorganisms during a blood meal from an infected host (human or animal) and later transmit it into a new host, after the pathogen has replicated. Often, once a vector becomes infectious, they are capable of transmitting the pathogen for the rest of their life during each subsequent bite/blood meal. Vector-borne diseases Vector-borne diseases are human illnesses caused by parasites, viruses and bacteria that are transmitted by vectors. Every year there are more than 700,000 deaths from diseases such as malaria, dengue, schistosomiasis, human African trypanosomiasis, leishmaniasis, Chagas disease, yellow fever, Japanese encephalitis and onchocerciasis. The burden of these diseases is highest in tropical and subtropical areas, and they disproportionately affect the poorest populations. Since 2014, major outbreaks of dengue, malaria, chikungunya, yellow fever and Zika have afflicted populations, claimed lives, and overwhelmed health systems in many countries. Other diseases such as Chikungunya, leishmaniasis and lymphatic filariasis cause chronic suffering, life-long morbidity, disability and occasional stigmatisation. Distribution of vector-borne diseases is determined by a complex set of demographic, environmental and social factors. Global travel and trade, unplanned urbanization, and en List of vector-borne diseases, according to their vector The following table is a non-exhaustive list of vector-borne disease, ordered according to the vector by which it is transmitted. The list also illustrates the type of pathogen that causes the disease in humans. Vector Disease caused Type of pathogen Mosquito Aedes Chikungunya Dengue Lymphatic filariasis Rift Valley fever Yellow Fever Zika Virus Virus Parasite Virus Virus Virus Anopheles Lymphatic filariasis Malaria Parasite Parasite Culex Japanese encephalitis Lymphatic filariasis West Nile fever Virus Parasite Virus Aquatic snails Schistosomiasis (bilharziasis) Parasite Blackflies Onchocerciasis (river blindness) Parasite Fleas Plague (transmitted from rats to humans) Tungiasis Bacteria Ectoparasite Lice Typhus Louse-borne relapsing fever Bacteria Bacteria Sandflies Leishmaniasis Sandfly fever (phlebotomus fever) Parasite Virus Ticks Crimean-Congo haemorrhagic fever Lyme disease Relapsing fever (borreliosis) Rickettsial diseases (eg: spotted fever and Q fever) Tick-borne encephalitis Tularaemia Virus Bacteria Bacteria Bacteria Virus Bacteria Triatome bugs Chagas disease (American trypanosomiasis) Parasite Tsetse flies Sleeping sickness (African trypanosomiasis) Parasite WHO response The "Global Vector Control Response (GVCR) 2017-2030" was approved by the World Health Assembly in 2017. It provides strategic guidance to countries and development partners for urgent strengthening of vector control as a fundamental approach to preventing disease and responding to outbreaks. To achieve this a re-alignment of vector control programmes is required, supported by increased technical capacity, improved infrastructure, strengthened monitoring and surveillance systems, and greater community mobilization. Ultimately, this will support implementation of a comprehensive approach to vector control that will enable the achievement of disease-specific national and global goals and contribute to achievement of the Sustainable Development Goals and Universal Health Coverage. WHO Secretariat provides strategic, normative and technical guidance to countries and development partners for strengthening vector control as a fundamental approach based on GVCR to preventing disease and responding to outbreaks. Specifically WHO responds to vector-borne diseases by: providing evidence-based guidance for controlling vectors and protecting people against infection; providing technical support to countries so that they can effectively manage cases and outbreaks; supporting countries to improve their reporting systems and capture the true burden of the disease; providing training (capacity building) on clinical management, diagnosis and vector control with support from some of its collaborating centres; and supporting the development and evaluation of new tools, technologies and approaches for vector-borne diseases, including vector control and disease management technologies. A crucial element in reducing the burden of vector-borne diseases is behavioural change. WHO works with partners to provide education and improve public awareness, so that people know how to protect themselves and their communities from mosquitoes, ticks, bugs, flies and other vectors. Access to water and sanitation is a very important factor in disease control and elimination. WHO works together with many different government sectors to improve water storage, sanitation, thereby helping to control these diseases at the community level.

Insect Features Transcript

his lecture in Insects and the Environment is on the topic of insect features. I'm Brendan Hunt. Knowledge of general insect features is important to understanding the roles played by insects in the environment, including the basis of specialized traits and the presence of limiting factors during insect evolution. Here are some general features you may already be familiar with. Insects have six legs. They have one or two pairs of wings, and they have three major body parts. The head, the thorax, and the abdomen. The insect body has a soft interior that is protected by a rigid exterior called an exoskeleton. The insect exoskeleton provides protection from desiccation or water loss and protection from bodily injury by serving as armor. The exoskeleton also serves as the point of attachment for musculature and provides structure to the insect body. The presence of an exoskeleton necessitates molting, or shedding of the old exoskeleton. This occurs when the exoskeleton has been outgrown. In the case of a grub-like larva, the soft body can grow flexibly, but molting is still necessary for growth of the hard parts of the head. This process of growth, molting and metamorphosis is regulated by hormones. Hormones are chemical signaling molecules in the body. Insect development proceeds in different ways in distinct groups of insects. The ametabolous insects, such as silverfish, have young that look like miniature versions of adults. These insects do not have wings at any stage. The hemimetabolous insects, such as aphids, stink bugs and roaches, have young called nymphs that lack wings and look slightly different from the winged adults. This form of development is known as incomplete metamorphosis. Holometabolous insects, such as butterflies, beetles, flies, and bees have young called larvae, which lack wings, followed by a pupal stage where a dramatic transformation into an adult that differs greatly in appearance from immature stages occurs. This form of development is known as complete metamorphosis. The insect head houses the brain and sensory organs and has mouthparts comprised of four main components, which are modified in different ways for specialized feeding behaviors in different groups of insects. The insect thorax is the point of attachment for legs and wings. Some groups of insects have major wing modifications, like hard outer wings in beetles, or the presence of only one pair of wings in flies. The insect abdomen houses the majority of internal organ systems, including components of the nervous, digestive, respiratory, and circulatory systems. The abdomen is also the location of reproductive organs. The insect digestive system is divided into four main sections which perform distinct roles. The insect respiratory system differs fundamentally from humans. Instead of breathing air through their mouths, insects have openings called spiracles along their bodies for air passage. These spiracles connect to branching tubes called trachea, which facilitate gas exchange throughout the internal tissues of the body. The blood of insects is known as hemolymph. The circulatory systems of insects are quite simple and open compared to those of vertebrate animals. Finally, the central nervous system of insects consists of a brain and ventral nerve cord. As we will see in this course, a brain so small is nevertheless capable of coordinating a remarkable repertoire of behaviors. I hope you enjoy viewing the documentary I've selected to help you learn about insect features. It's called 'Insect Dissection: How Insects Work,' and is viewable from eLC.

Biomass

represents stored energy in a connected ecosystem

Adverse Conditions

some insects are specialized to live in the harshest and deadliest conditions Alkali flies: perhaps the pnly type of fly able to survive California's harshest water environments

Taxonomic diversity

the diversity of species that belong to a group of organisms

hibernating butterflies

vulnerable to predators monarch butterflies are poisonous but natural selction allows a few birds to learn how to get rid of the toxic parts and prey on the monarch butterflies, killing hundreds of thousands every year monarch butterflies that do survive stay huddled together until the spring

Plant-Herbivore Interactions

Today's lecture in Insects and the Environment is on the topic of Plant-Herbivore Interactions. I'm Brendan Hunt. A trophic level is the positioning of an organism in the food chain. The first trophic level is made up of producers, which are typically plants. The second trophic level is made up of herbivores, which eat plants and are called primary consumers. The third trophic level is made up of carnivores that eat herbivores. And the fourth trophic level is made up of carnivores that eat other carnivores. Energy is transferred from one trophic level to the next, but only around 10 percent of the energy transfer between trophic levels is converted to biomass. An understanding of plant- herbivore interactions is fundamental to appreciating the importance of insects in ecosystems, agriculture, forestry, horticulture, biological control, and conservation. Insect herbivores are highly diverse, with species belonging to nine different orders, and they have a wide variety of feeding styles. Plants have evolved barriers to herbivory and many herbivores have evolve strategies to counter plant defenses. The distribution and abundance of plants and herbivores is often intertwined. At least half of described insect species feed on living plant material, which is known as phytophagy. Herbivores can be classified in several ways. One is by diet breadth. Does the herbivore specialize on one or a few species of plants, or is it a generalist? Another system of classification is by diet guild, where each guild is a group defined by how the herbivore obtains and processes its plant diet. Feeding guilds include chewers or sap feeders and free living or concealed feeders. And an insect may change its diet and feeding guild throughout its lifecycle. Specialist herbivores which limit their diets to one or a few species, may have evolved the ability to tolerate specialized host plant defense, or manipulate its host to its benefit. Generalists, on the other hand, feed on a wide variety of plant species, but as a trade off, are unlikely to be able to overcome a specialized plant defense. Most, but not all insect herbivores exhibit some level of specialization. Among insect herbivore feeding guilds are suckers, a group of insect herbivores that feeds on plant xylem, phloem, and sap. Many insects from the order Hemiptera are suckers, including planthoppers, leafhoppers, lace bugs, aphids, whiteflies and cicadas. Chewers are a feeding guild that chew on plant leaves, roots, flowers, or fruits. Examples of chewers include species of caterpillars, grasshoppers, beetles, sawflies, and maggots. Leaf miners feed on the inner portion of the leaf. This can be a form of concealed feeding, as is boring into other plant parts to feed. Examples of leaf miners include species of maggots, caterpillars, and sawflies. Gallers induce plant tissue growth by stimulating a plant hormonal response. The resulting growth is called a gall. Larvae feed on galls, which also offer concealment. Some species of flies, wasps, aphids and thrips are gallers. Living organisms are composed of the major elements carbon, nitrogen, and phosphorus. From an insect's diet, proteins are broken down into amino acids which are used in enzymes and structural proteins. Carbohydrates are used as energy sources and structural components. Fats are used in the synthesis of hormones and cell membranes. And vitamins are necessary for proper metabolism, with many acting as cofactors for enzymes. The study of the relative balance or ratio of key elements in organisms is known as ecological stoichiometry. Importantly, the relative amounts of carbon, nitrogen, and phosphorus differ in organisms from different trophic levels. Plants have a lower percentage of nitrogen and phosphorus than animals. As a result, herbivorous insects must implement strategies to obtain sufficient nitrogen and phosphorus and eliminate excess carbon from their diets. The potential nutrient deficiency of a plant-based diet relative to an animal-based diet is readily overcome by insect herbivores in a number of ways. These strategies include eating more food, selecting nutrient rich foods like young leaves and seeds, and synchronization of the insect lifecycle with the availability of nutrient rich foods. The figure shown provides an example of lifecycle synchronization, with the abundance of the green spruce aphid plotted in the top panel, and the seasonal changes in the nitrogen content of its host tree plotted in the bottom panel. Along the x-axis, you can see the months of the year. Fluctuations in aphid population size mirror changes in the nitrogen content of spruce, with peak aphid reproduction occurring in spring when trees are most nutritious, and aphid dispersal via winged adults coincident with a precipitous drop in nitrogen in early summer when wingless females are produced. Herbivores also implement strategies such as manipulation of plant physiology to form energy sinks or may even complement their primarily herbivore diet with high nitrogen non plant sources. Given the prevalence of herbivores, it's no wonder that plants have evolved diverse defensive strategies to protect themselves from herbivory. One of the two major classes of plant defenses against herbivores include mechanical and structural barriers to herbivory. These include spines, defensive hairs known as trichomes, tough, waxy tissue, and latex. The second major class of plant defenses against herbivores include chemical barriers to herbivory. Many botanical insecticides have long been known and used by humans. As early as 1690 extracts of tobacco were used to kill sap feeding insects. In 1848 rotenone from legumes was found to be effective for controlling caterpillars. And as early as 1880 humans were using pyrethrum from Chrysanthemum flowers as a general insecticide. These chemicals are examples of allelochemicals, which are secondary metabolites with no known functional role in plant growth and reproduction. Plant chemical defenses of this nature generally operate either as toxins, which interfere with insect metabolism, or as digestibility reducers. Milkweed plants provide a fascinating example of plant defenses. These plants produce cardenolides, which interfere with sodium-potassium pumps in animal cells. In mammals, these compounds lead to an increase in cell sodium and calcium ion concentrations, which can lead to cardiac arrest. With correct dosage, however, cardenolides can be used to manage some heart conditions. Milkweeds also have physical defenses against herbivory in the form of latex exudation and leaf toughness, demonstrating that plants often employ both chemical and physical defenses for protection. Many toxins are produced by plants, and some of these have pharmacological properties that are widely used by humans, such as nicotine, opiates, cocaine, caffeine, strychnine, and cannabinoids. Other insect toxins contribute to the flavor and scent of eucalyptus cinnamon cloves, ginger, menthol, and camphor, among others. Plant defenses can be constitutive, meaning they are always present in the plant, or they can be induced, meaning they increase in response to damage or the presence of insect- specific compounds. Plant defenses can also be direct, meaning they directly affect herbivores, or indirect, through the recruitment of herbivore enemies. Recruitment of herbivore enemies can be achieved because both herbivores and their natural enemies use plant volatile chemicals as cues to locate a plant. Here an herbivorous butterfly and aphid are attracted to milkweed. But natural predators of these aphids and caterpillars can perceive the same cues to direct their hunting efforts to milkweed plants. Given the impressiveness of milkweed defenses, you may be thinking to yourself, how do monarchs overcome these defenses? The answer is through a combination of behavioral and physiological adaptations. To overcome physical defenses, monarch caterpillars shave the trichomes off leaves and drain latex prior to feeding. Monarchs have also overcome the chemical defense of milkweed through genetic change in a protein that helps form the structure of the sodium potassium pump in their cells, such that cardenolides no longer bind and interfere. In a fantastic case of convergent evolution, the same molecular adaptation evolved independently at least four times, in beetles, butterflies, bugs, and flies that all feed on milkweed. And beyond overcoming plant defenses, some specialist insect herbivores use plant defensive toxins to their own advantage. Through toxin sequestration, insects can uptake plant toxins into their own bodies, making themselves distasteful and toxic to predators. Monarch butterflies are among several insects that sequester cardenolides from milkweeds. As this blue jay's reaction illustrates, monarchs are not a desirable prey item as a result. As a final note, the defenses of plants and the strategies employed by herbivores to overcome them provide a framework for potential co-evolutionary arms races to occur between specialist herbivores and the plants they eat. This can lead to step-wise reciprocal changes in defenses and herbivore adaptations over the course of evolutionary time.

Pollination

Today's lecture in Insects and the Environment is on the topic of Pollination. I'm Brendan Hunt. Pollination results in plant sexual reproduction, which promotes genetic diversity in plant populations. Pollination occurs by the transfer of pollen grains from the male anther of a flower to the female stigma of a flower, where the pollen fertilizes the female gamete, which develops into a seed. When a plant is pollinated by its own pollen, this is known as self pollination. When a plant is pollinated by another plant's pollen, this is known as cross-pollination. Many plants, like pine trees and many grasses, disperse pollen through the wind. This explains why there is an onslaught of airborne pollen every spring in Georgia. Most flowering plants, by contrast, rely on animal pollination. Animal pollination is usually the unintended consequence of an animal's feeding activity on a flower. Animal pollinators include bees, beetles, butterflies, moths, flies, hummingbirds, and bats. Among these animal pollinators, butterflies travel the furthest, but bees transfer the most pollen between flowers and are the true stars of the pollinator world. This is a diagram of a flower showing the anthers which contain pollen and the stigma which receives the pollen so that seeds can be fertilized. Animal pollinators are often sipping nectar and pollen grains attach themselves to the animal's body. But they may also be collecting pollen as a high protein food source. When the animal visits another flower, for the same reason, pollen can fall off onto the flower stigma and may result in successful reproduction of the flower. Bees have special pollen collecting structures made up of dense groups of hairs referred to as pollen baskets. These are used to collect pollen to provision bee larvae because pollen provides an ideal high protein diet to support larval development. Of an estimated 352 thousand flower species on the planet over three-fourths are animal pollinated. It is safe to say that animal pollinators play an extremely critical role in the life cycles of many diverse plant species in natural ecosystems. It is also estimated that around 35 percent of total crop production depends on animal pollination. Examples of crops where animal pollination is essential for fruit production include squash and melons. Examples of crops where animal pollination results in a large increase in fruit yield include almonds, apples, avocados, cherries, peaches, pears, cucumbers, blackberries, blueberries, and raspberries among others. Pollination can fail through a number of mechanisms. Pollen can be lost to the environment or fail to disperse. Pollen can become sterile during transport or may be insufficient in amount if flower and pollinator densities are low. Pollen can also be incompatible with self-fertilization or pollen from other species may block the way for pollen from the same species. Another form of pollination failure is represented by nectar robbing, where nectar feeding occurs without the chance of pollination. This behavior is performed selectively on flowers whose nectar is concealed or hard to reach. In nectar robbing, robbers pierce or use an existing hole in the tubular corolla at the base of the flower to access its nectar. Agriculturally important managed pollinators include honey bees, bumblebees, Blue Orchard bees, and alfalfa leafcutter bees. Threats to unmanaged native pollinators include insecticides and habitat degradation. These are also threats for managed pollinators like honey bees, particularly in the case of insecticide exposure. But additional stressors affect managed species in the form of agricultural practices such as transport and increased densities that favor disease and parasite transmission. Together, these factors can lead to colony collapse disorder in honey bees. Bees are a highly diverse group of organisms with over 20,000 species on the planet and around 4 thousand species in the US and Canada alone. Most of these species are not eusocial. Notably, the iconic European honey bee is not native to America. Managed and invasive bee species compete with native species. Over 80 bee species have been introduced to new regions around the globe. And both management and eusocial colony formation tend to magnify the impacts of introduced species on native bee species. This flowchart was developed by researchers to categorize the continuum of hypothetical impacts of different bee species on native bees, an important consideration for the conservation of pollinator species in their native ranges. One takeaway is that conservation of honey bees in the US does not aid the goal of native bee conservation. In fact, honey bees themselves pose threats to native bee species through competition and pathogen transmission. Steps we can take to care for native pollinators include reducing insecticide applications, particularly to flowering plants, preventing further non-native species introductions and providing floral resources and nesting habitat to support pollinators. A great way to provide more habitat to pollinators is to let diverse native plant species overtake areas with monoculture grass lawns, or to maintain patches of wild flowers. In association with this lecture, I've included a documentary called My Garden of a Thousand Bees from Martin Dohrn, who also wrote and produced Attenborough's Ant Mountain, another video available in this module. The up-close and personal look Dohrn provides into the lives of bees during the coronavirus pandemic is really unlike anything I've seen before. I hope you enjoy it as much as I did!

Social Insects

Today's lecture in Insects and the Environment is on the topic of Social Insects. I'm Brendan Hunt. Social behavior encompasses interactions among individuals belonging to the same species. Such interactions create opportunities for cooperation and conflict. And the fitness consequences of these interactions can be used to categorize types of social behaviors. Imagine an actor who performs a behavior and a recipient who is affected by the behavior. In this scenario, the behavior will be mutually beneficial when the fitness of both individuals benefit. An example would be removing parasites from one another. A selfish behavior benefits the actor while harming the recipient. An example would be stealing food. Altruism represents an interesting contrast in that an individual detracts from their own fitness and increases another's fitness. An example would be donating one's food to another. Finally, spite describes a behavior that lowers the fitness of both the actor and the recipient. An insects society is a group of individuals from the same species that cooperates and shares resources. These resources can include shelter, defense, and food. Insect societies originated as single-family groups, but in many contemporary species, insect societies are formed by multiple family groups. Defining the degree or level of the social behaviors exhibited by a species is challenging and not without controversy. But the most widely used terminology to do so was coined by EO Wilson in 1971 Wilson's system of social classification is based on the presence or absence of three criteria. First, do individuals cooperatively care for the young? Second, are non-reproductive individuals present that act to help reproductive individuals? And finally, do adult offspring assist their parents, representing cooperation between generations? Based on Wilson's system, species that are absent of all three criteria are considered solitary, subsocial, or communal based on other criteria. Species are considered quasisocial if they exhibit cooperative brood care but lack reproductive castes are overlapping generations. Species are considered semisocial if they exhibit cooperative brood care and reproductive castes, but lack cooperation between overlapping generations. And finally, eusocial species are those that exhibit cooperative brood care, have reproductive castes, and have adult offspring assisting the parental generation. Insects considered to be solitary show no cooperation among individuals, but usually do have some form of social interaction with their mates. Marking an important contrast, subsocial insects are those that exhibit parental care of offspring and live in family groups for at least some portion of their lifecycle. Parental care is observed in thousands of insect species from at least 15 orders. The social behaviors involved in parental care range from passive egg guarding to grooming, feeding, defense, and nesting. Earwigs provide an example of a subsocial lifestyle because they exhibit maternal care. Mothers defend their eggs from predators and keep them clean. Nymphs then live with their mother until their second molt, with mom providing food up until this point. An example of biparental care comes from burying beetles, which partially digest and process carrion into a horrifically disgusting meat ball that they feed to their larvae. YUM! Communal species are those where members of the same generation live together but without cooperative care of the young. Examples of communal species include aphids, which benefit from alarm signaling and nutrients sinks, and tent caterpillars, which benefit from group defensive displays and the marking of foraging trails. Quasisocial and semisocial are less commonly used terms that fill in some gray areas. Quasisocial species are similar to communal species, but they cooperate in caring for their brood. Examples include cooperative breeding groups in Burying Beetles and bees where sisters lay eggs in a shared nest. Semisocial species are similar to eusocial species in that there are individuals that forego reproduction and assist others. But offspring don't share a nest with their parents as adults. Examples include some paper wasps, which are more typically eusocial, but that in this case, found nests as groups and maintain a reproductive dominance hierarchy, without assistance from adult offspring. Living in groups offers advantages and costs. The benefits can include defense against predation, increased food acquisition, and gaining access to an ideal nesting site. The costs of group living, on the other hand, can include increased competition for resources, transmission of disease and parasites, and detection of the group by natural enemies. The ultimate form of social behavior is eusociality, where individuals participate in cooperative brood care, assist their parents as adults, and most importantly, form a reproductive division of labor with distinct castes. Castes include individuals that are specialized for reproduction, like a queen. And individuals that are specialized for tasks associated with brood care, foraging and nest construction, maintenance, and defense. These individuals are known as workers. Eusocial behavior has arisen independently in multiple lineages, most of them in the order Hymenoptera, which includes ants, bees and wasps. In the hymenopteran lineages were eusociality evolved, nesting behavior appears to have already been present. Nest building and care of larvae appears to have been a necessary precondition for the evolution of cooperative breeding and eusociality. This should not come as a surprise, as eusocial insects are known to form colonies that share and defend the nest. Eusocial insects include all termites which belong to the order Blattodea. Termites evolved from non-eusocial roaches. Eusocial insects also include some species of bees and nearly all ants, which each evolved from non-eusocial wasp lineages. Some lineages of wasps also evolved eusociality. Finally, rare examples of eusocial species exist among aphid and thrips species. Paper wasps provide an example of a eusocial life cycle. They occur throughout most of the world and make open nests out of paper. Queens, which lay eggs, and workers, which do not, are not morphologically distinct in paper wasps, unlike so-called advanced eusocial insects, like yellow jackets, honey bees, or ants. Let's walk through the life cycle of a typical paper wasp in North America. In early spring, a female wasp emerges from hibernation, builds a small nest and lays her fertilized eggs. This queen hunts for insect prey to feed her developing workers. At this point in her life, she performs all foraging and nest construction tasks herself. By midsummer, the first group of daughters of the queen have eclosed as adults. They have taken over foraging and nest construction duties. The queen is now able to stay at the nest full-time, and the colony grows. In late summer to early autumn, the queen lays fertilized eggs that will emerge as non-working future queens. Or in the case of unfertilized eggs, they will become males. This is because hymenopteran insects have a sex determination system where males come from unfertilized eggs and females come from fertilized eggs. Once they reach adulthood, these future queens and males depart on nuptial flights and mate. In the autumn, the old queen, the workers and the males all die. The newly mated queens, on the other hand, hibernate until spring when they will found their own new colonies. This illustration summarizes the paper wasp lifecycle. In some paper wasp species, potential queens battle with one another upon coming out of hibernation in order to establish a reproductive dominance hierarchy. Amazingly, researchers have shown that one such species has evolved variable facial patterns and facial recognition abilities. So they are able to remember whether an individual was dominant in a prior dual. In contrast to paper wasps, many eusocial species have highly distinct reproductive and worker castes. This is often referred to as advanced eusociality. And such species often form very large colonies. Examples include honey bees and leafcutter ants. The castes of advanced eusocial species are models of developmental plasticity with cast fate during development being determined by nutritional differences in most species. As an example of caste differentiation, we can look to the southern yellow jacket, a eusocial wasp. The first several molts a female larvae do not differentiate into queen- and worker-destined groups, but the later instars develop at different rates and grow to different sizes. So that by pupation there are two distinct groups of female individuals, queens and workers. Which females will become workers or queens is predetermined by the size of the nest cell an egg is laid in. The workers then feed the developing larvae accordingly. European honey bees are the best known and best studied eusocial insect species. Honey bees are managed throughout the world as crop pollinators. Workers communicate information about the distance and direction of floral resources with a remarkable communication system known as the waggle dance. Weaver ants are an advanced eusocial species with impressive cooperative nest building behaviors. They make nests from leaves that are folded together by living bridges of adult workers. Larvae, meanwhile, are used as a source of silk to fasten the leaves together. Termites belong to an order different from bees, ants and wasps. They live in nests that are typically found in or near their food source. Unlike eusocial hymenoptera, termite workers are both female and male. Although eusocial insects make up only around 2% of described insect species, they account for an estimated 50 percent of the total biomass of insects on the planet. This makes them particularly impactful in ecosystems and particularly problematic as invasive species. How is it that eusocial insects coordinate complex tasks? This requires communication -and waggle dance aside- communication in eusocial insects is achieved primarily through pheromones. Pheromones inhibit reproduction of workers and promote colony cohesion. Alarm pheromones alert others to an intruder or danger. Colony specific pheromones allow nestmate recognition and trail pheromones lead others to resources. An important concept to the evolution of eusociality is that of a superorganism, a term first coined by EO Wilson as "Any society such as the colony of a eusocial insect species, possessing features of organization analogous to the physiological properties of a single organism." Wilson went on, "The insect colony, for example, is divided into reproductive castes analogous to gonads and worker castes analogous to somatic tissue. It may exchange nutrients by trophallaxis, analogous to the circulatory system, and so forth." The concept of a superorganism has been used to argue that eusocial species with truly sterile workers represent a major transition in the evolution of biological organization, along the lines of the transition from prokaryotes to eukaryotes, in which cells gained organelles, or the transition from single cell to multicellular organisms, in which tissue types and organ systems arose. The level of cooperation between individuals in a superorganism is not an intuitive outcome from an evolutionary biology perspective. So how did superorganisms originate? The answer lies in kin selection. The fundamental challenge to evolutionary biology posed by eusocial superorganisms lies in the origin of seemingly altruistic behavior, wherein workers forgo their own reproduction to assist their parents in rearing more siblings. In fact, Charles Darwin viewed the presence of altruism as a special difficulty, "Which at first appeared to me insuperable and actually fatal to my whole theory." But Darwin suspected that selection can favor traits that result in decreased fitness for an individual if they increase the fitness of close relatives. In the 1960s, William D. Hamilton devised a genetic model showing how a genetic variant causing altruistic behavior can spread in a population, called kin selection, where in altruism helps to pass on the same versions of genes that the workers themselves carry. Genes are transmitted to future generations by their siblings that develop into future Queens. For this module, I've selected my favorite episode of life in the undergrowth, an episode that discusses the evolution of eusociality and provides an up-close look at some remarkable eusocial insects. An expanded dive into the biology of the wood ants featured in the life and the undergrowth episode is taken in Attenborough's ant Mountain, which is filmed with the latest technology. I highly recommend this second, optional video as well!

all kind of insects

develop chemical defenses to deter predators

Insect Dissection

has showed how insects survived on earth in ways that are different from us

Damselflies

seldom venture beyond their homes stream but some fly huge distances

There are more kinds of insects in the world

than all other kinds of animals put together

White mush

fat body store tissue, holding protein, fats, and other nutrients

Japanese Red Bugs

-Parent insects don't care for their offspring -but Japanese Red Bugs do by helping their offpsrings feast on the perfect fruit -The more offspring, the more fruit that the parent insect has to bring in order to feed the offspring... until she dies and the offspring must now fend for themselves

Why Study Insects?

-They are the dominant group of terrerstrial animals on the planet

Three Metrics that Make Insects Dominant

-Total number of individuals that reside in the environment -Total biomass or combined weight of insects in the environ) ment. -Insects are uniquely diverse (Number of total insect species and in the ecological roles they play

Insects outnumber humans

200 million to 1 This is a "Bugs" world

Aquatic Insects

found in puddles, tree holes, ponds, lakes, streams, rivers, tidal marshes, and hot springs

The digestive system

For insects, nutrients pass through the tube wall either straight into tissues that need them, or in the fat body where they are stored for use later longer tubes are used for breaking down food and collecting waste Crop: an expandable sac that stores food before it gets to the stomach to be digested insects can eat pretty much anything

The general idea of the video

I see a lot of applications to Darwin's theory of evolution. Especially with the insects (can't remember the name) getting away from the frogs. The narrator states, "only the fastest get away" which goes a long with the concept of "survival of the fittest"

DAvid Attenborough's Ant Mountain

The Jura Mountains on the French Swiss border are in the grip of winter. The ground has been frozen solid for months. This is a tough place in which to live. I'm told that clearings like these could be the home of a real giant. At this time of the year, it'll be in hiding. But evidence of its existence. These strange mounds, is everywhere. Inside here, deep down and protected from the cold. The giant is a sleep. Beneath the thatch of spruce needles lies a maze of tunnels and chambers. The home of hibernating wood ants. Individually, they are tiny, but they're members of a giant supercolony. When temperatures rise over 0.5 billion of them will emerge and dominate this landscape. Scientists are only just working out how ants manage to survive up here. But in fact, there's a much greater, a more profound mystery that has brought me up this mountain. Among ants, cooperation between colonies is very rare. Warfare is common. Yet these nests over a great area live at peace with one another. This may sound like an epic tale of war and peace, but does it also contain an echo of human nature? These ants, in some extraordinary way have exchanged war for peace. It is now recognised as one of the largest of all insect super societies. And its very existence conflicts with some of the laws of evolution, as we presently understand them. It's been a long cold winter here in the Swiss Jura Mountains. It's hard to believe that any insect could survive in this frozen landscape. But now change is in the air. Soon ant nests all over this mountain will come to life. Some of these mounds are independent colonies, but others are part of one, huge supercolony. Over the coming months. I will be looking at the differences between these two wood ant societies. One that wages war with all its neighbours and the other, which welcomes them and lives at peace. As the grip of winter eases, sentries emerge from the mounds to cheque on conditions. They detect the sign that they've been waiting for. The temperatures are rising. Spring is on the way. The ants survived the winter thanks to their own central heating system. Warmth given off by the slow decomposition of the dead vegetation in the nest's fabric, and that prevented them all from freezing. Now by swarming all over the surface of the nest, there are recharging their batteries, absorbing heat directly from the sun's rays. This behavior only happens over one or two days in the early spring. The worker ants have emerged into the sunshine and are now clumping together. And they're not just sun bathing. It could well be that the ultraviolet rays of the sun cure them of any infections from viruses or fungi that may have happened during their long sleep underground. You can almost feel the enthusiasm with which these little creatures are enjoying their sunbathe. This is unusual enough, but now here is something truly extraordinary. There is a queen. She's almost twice the size of her subjects. She's also the most important member of her family. Are what's more, there's another. To see a queen exposed and vulnerable outside the nest is very rare indeed. There's one. And there's another. Shining wonderfully in sunshine. A normal wood ant nest usually has just a single queen who lays all the eggs. But clearly this is not so here. There's another, there's another. Several of them. Amazing. After a few moments in the sunshine, the only time they see daylight in the whole year, the queens disappear and make their way back to the brood chambers deep in the nest. Those unwilling to go are dragged back. We may call them queens, but there's no sovereign rule here. The workers govern by consensus and they decide when and where the queens will go. There maybe hundreds of queens in this single nest. And there are over a thousand such mounds as this, all interconnected. So, across the supercolony there maybe as many as a million queens. It's now early April. The queens return below to prepare for the egg-laying started a race against the clock. They must complete their most important work below in the next two months. Using infrared light, which is invisible to the ants, we can watch them inside their nest without disturbing them. Most of the first eggs to be laid will produce the next generation of breeding individuals, the queens and the males, both of whom will have wings. Inside the 1000 nests of the supercolony over 0.5 billion, mostly unrelated worker ants, cooperate to ensure that the queens and the males will be ready for their mating flights in mid-June. With all these developments on the way, it's imperative that the workers collect more food as soon as possible. But many of the mounds are still surrounded by snow. So the workers can't reach their feeding grounds. But there's something they can collect. Heat. The nest needs more heat than that which comes from the rotting vegetation, if the eggs are to hatch in time for their June appointment. Now, however, the ants have another source of warmth. Using their bodies are solar panels the ants harvest the sunlight. We have a heat sensitive camera that detects differences in temperature. The nest appears black because it's hotter than the surrounding environment. It shows a similar difference in the ants. Those going down into the nest are black because they'd been heated by the sun. Whereas those coming out are white because they're cold, having transferred their body heat to their charges in the brood chambers below. It's this kind of selfless collaboration that is the key to success of any ant colony. In normal ant colonies, all the workers are related to one another, and to the queen. The theory is that that is why they all cooperate. But that is not the case here. There are hundreds of queens here, over a 1000 have been counted in a single nest. So all the workers can't have the same parents and genetics have confirmed that this is so. It's this cooperation between unrelated ants in a single colony that appears to be rewriting the rules of insect evolution. But we still don't really know how this has come about. Spring is now well on the way. The snow has disappeared and colour comes to the meadows. By late April, there are piles of eggs in the nest, and the first larvae are hatching. The workers labour unceasingly to ensure that the growing brood will be ready to emerge in six weeks time. At the peak of the short Jura summer. But not every ant nest on this mountain can be so focused. Some will soon have to deal with threats to their very survival. Just a short distance away on the borders of the supercolony's woodland territory, there are other wood ants. The mounds here on this side of the mountain look exactly the same as those of the supercolony. And so do the ants themselves. The inhabitants of each nest here, are all the offspring of its single queen. And the colonies compete aggressively with one another. After the winter hibernation, the territories between that nest over there, and this one here have become blurred, and the frontier has to be reestablished. And in order to do that, workers from both nests are now scouring the ground. And that brings neighbouring ants into contact for the first time this season. When foragers from the different nests meet, they immediately recognise that they're from rival families. They then dash back to their nests and within minutes, both colonies know that territory on their frontier is being disputed. Armies assemble. This is war, and the weapons being used are chemical. Formic acid. I can smell it in the air. They're squirting it from the ends of their abdomens. And if they can bite their opponents so that the formic acid gets beneath the outer shell of an ant, it will dissolve its internal organs. As they grapple, each tries to restrain its opponent by clamping its jaws around a leg or an antenna. Soldiers from both sides target that opponents limbs. It could take seven ants to subdue a single enemy. One holds each leg, and the seventh uses its mandibles to cut open sections of their opponent's exoskeleton, exposing the insides. An attacker brings forward its abdomen under its body and squirts acid onto its victim. Battles are going on everywhere. Each colony carries its own chemical badge, invisible to our eyes, but clear to the ants' sensitive antennae. Fighters touch each other to confirm whose side they're on. Here and there, individuals clamber up the vegetation. Are they having a rest or are they surveying progress to see where help is needed? The smell of formic acid reaches the colony and more ants from both sides run to join the battle. These wars can continue for over a week. At their peak, many thousands are fighting and thousands are killed. The victors will certainly have enlarged their territory. But some say they have also gained other rewards. They're taking off the bodies of their victims and carrying them back to their nest, over there, to feast upon them. Both sides have suffered heavy losses. For the ants in the meadow, it has been a costly start to the year. Higher up the mountain in the territory of the supercolony, the inhabitants of different nests are also meeting. But here things are very different. These ants come from a mound about half a mile away. If that mound was a separate, independent colony, then these, when they land there, will be savagely attacked. But let's see what happens. At first, the resident ant makes an aggressive gesture. But then the other strokes the first's antennae. That gesture is a request for food, and the other obligingly feeds her. This behaviour, known as trophallaxis is in itself not unusual. Most ants do it at times. What is unique is that these ants are almost certainly unrelated. Yet they treat each other as if they were from the same nest. They do this because they share the supercolony scent, a chemical signature that is transferred together with the food. In one experiment, scientists fed a distinctive chemical to a nest on one side of the supercolony, And eight weeks later, that same chemical appeared far away on the other side. It's this sharing of food between over 0.5 billion individuals that makes this super society so truly remarkable. Because of this, supercolony ants can move freely between mounds and they have, as a result, created over a 100 kilometres of trails that link over a thousand nests. These trails not only allow the ants to make new nests deep in the forest, they also give all the members of the supercolony access to resources of great value to them. It comes from the spruce trees. The ants don't feed directly on the spruce trees. They become farmers and these are their flocks. Aphids. The presence of the ants keeps insect predators at bay so the aphids can feed unmolested. They drink the tree sap and excrete what they don't need as a sugary liquid called honeydew. And the ants love it. Just as human farmer's milk their cows, so the ants stroke the aphids with their antennae to persuade them to release the honeydew. Once the aphids are milked and the ants have drunk as much honeydew as they can carry, they head down the tree, abdomens bulging, and return to the nest. The honeydew is not only food with which to sustain themselves. Some use it to raise the heat of their bodies well above normal and so warm the atmosphere within the nest. A valuable ability in the fickle climate of the Jura. The spruce trees themselves also produce a substance that the ants can use directly. These ants have connected little flakes of resin. That's a sort of gum that oozes from the broken trunk of a tree. The tree uses it to seal off an injury. But what are the ants using it for? Inside the nest, the extra warmth produced by honeydew helps the queens to keep laying, and the larvae to keep growing. However, constant warmth can create problems. Despite regular cleaning, diseases can thrive. The ants have a remarkable solution to that problem. They cover the surface of the mounds with tiny nuggets of resin and also take it into the chambers below. One nest contained over four kilos of it. It is, in fact, ant medicine. The ants combine acid from their bodies with the resin, and so produce a very effective antibiotic. This is one of the most sophisticated animal pharmacologies known to science. It's been shown that wood ants living in nests that contain resin are better able to survive diseases than those that don't. And the eggs are far less likely to be infected by fungi. This immense, peaceful supercolony has few enemies. But now, at the end of May, a new threat has arrived. The Jura is famous for producing some of Europe's finest cheese. For generations, farmers have made small clearings in the woods to create meadows where cattle can graze. Only now is it warm enough for cows to be brought up to these high pastures. Somehow, the ants need to make sure that they're left alone and that nothing damages their nests. And that's a considerable challenge even for a supercolony. But these ants are very determined. When one squirts it's acid, others follow suit. The result is a coordinated barrage. The cows are not harmed, but they do get a dose of acid in the nose, which they don't like, and they tend thereafter to avoid these mountains. By now in June, the larvae have become big and greedy. They must be given special care because they will produce the next generation of royalty. So the workers labour hard to meet their demands. In summer, hundreds of thousands of eggs are hatching every day and honeydew is not enough. The ants go in search of something else, a supplement. Fresh meat. The lush green hills and mountains of the Jura are now teaming with all sorts of life. And nearly all of it is potential food. The ants spread out from the nest, scouring every square inch of the ground in search of prey. As the hunters approach, those that can take flight. The ant's vision is not very acute. They can only see a target if it moves. A wolf spider, however, can see the ants clearly. But as long as she doesn't move, they won't know that she's here. She's carrying a little sack full of eggs. She decides to run for it, and her sudden movement alerts the hunters. That first fleaking touched by an ant left a faint scent mark. And now fellow hunters can home in on their target. The spider has a venomous bite, but that is no use now. Eight powerful legs are her only hope. But her speed is the very thing that enables the ants to follow her. Slow motion reveals the basic ant hunting technique. Lunge with jaws open and hope for the best. At last, an ant manages to grab her. Like a pride of lions taking down a buffalo, the ants surround her to restrain their catch, while another delivers the fresh dissolving acid. The wolf spider is just one of many victims. Alone, an ant can take only the smallest prey. But by working as a team, they can capture creatures many times their size. A supercolony can make hundreds of millions of kills every year. Beatles, caterpillars, worms, flies, they will tackle almost any living thing. Whatever the prey, it's first cut up and eaten by the workers who then regurgitate it to feed to the larvae. Once they have grown to full size, the larvae spin silk cocoons for themselves. Inside each, a featureless larva is changing into an adult. Their time in the sun is approaching. Wood ants live in one of the most highly organised and complex of insect societies. They fight wars over territory. They hunt in packs and farm other species. They build complex homes with central heating. They produce their own medicine. And one group of them we now know, has made another advance. The supercolony has extended this collaboration beyond the frontiers of the family to form a super society of such dimensions that we can perhaps begin to compare it with that other great social creature on this planet, ourselves. People studying the origins of human culture suggests that shared myths were one of the factors that bound early human societies together. But what about ants? While in many species, it is certainly the case that all the individuals are very closely related to one another. But that is not so in the supercolony. And in some days in June, such colonists continue to break the rules. As midsummer approaches, the Jura briefly becomes a paradise of wild flowers. And something new appears inside each of the nests. Wings. A royal generation. Male and female, has finally hatched. And both will be able to fly. Winged individuals are the only ones that are capable of breeding. The males are little more than animated insemination devices. And they will soon achieve their purpose and die. But the females, which are emerging just now, this is the beginning of a long life of servitude. When the weather is just right, sunny and not too windy, the nests suddenly become covered with winged ants. There's an excitement in the air. The males, which have matte black bodies, are incapable of feeding themselves. So once they leave the nest, they only have a short time to live. There's no time to waste. The virgin queens who are also black but splendidly shiny, have a rather clumsy beginning to their lives. They're heavy with fat reserves and swollen ovaries. So that getting airborne is not easy for them. This is the most important flight of their lives, but it's also their first. Many test their wings before takeoff. They may need several attempts before they achieve complete flight control. Over a few days, 0.5 million winged ants of both sexes take to the air and head off for new territory. They then all assemble here in the heart of the supercolony. It's not clear how they find this meadow. But year after year, virgin males and females from across the supercolony are drawn here for their nuptial flight. The queens congregate in small patches of taller plants and begin to release sex pheromones, airborne chemicals that attract males. Detecting this scent on the wind, the males home in on the females. The virgin queens may only get the chance to mate once, And they need to obtain enough sperm to fertilise the eggs they will be producing for years to come. But with plenty of males in the meadow, they can afford to be choosy. The males are so driven, they even try to mate with females who are already doing so. Those males fortunate enough to couple quickly, make the most of their few remaining hours of life. Once they've mated, their service to the colony is over. And they die of exhaustion. The queens now have no further use for their wings. And they try to get rid of them. But they are necessarily rather firmly fixed. Trying to remove a backpack with your feet, even if you have six of them, is clearly a frustrating process. Eventually, the meadow is marked with little drifts of discarded wings. Such breeding swarms are fairly typical of ants generally. But now the queens of the supercolony do something much less common. To understand why they behave so differently, we must first return to the spring battlefields of the ordinary woods ants outside the empire of the supercolony. The warring colonies on this side of the mountain have now accepted their frontiers. And summer brings a brief pause in their battles. The mating system they use may seem at first sight to be the same as that of the supercolony, but in fact, it's fundamentally different. Every decision taken by a mated female is fraught with danger. The colony this queen comes from is at war with all its neighbours. So if she meets any of them, they will try to kill her. She needs a home, but she can't build it without help. Her solution to the problem is extraordinary, and radical. Under this rock, a different species, field ants, have built a nest. These small ants, less than a third of her size, are common and live in meadows on the edge of the forest. The only way this wood ant queen can get her own nest is by taking over one of theirs. She will become a parasitic queen. She lurks near the nest, trying to pick up the scent of the field ants. She avoids groups of them because they could overpower. Instead, she tackles individuals. There's a brief dual, and then she retreats. But each time she's left with a trace of their scent so that she slowly begins to build up a chemical disguise. These contests go on for several days. Gradually, her disguise becomes more and more convincing. The entrance to the field ants' nest is unguarded. Cautiously, she enters. Inside, she is vastly outnumbered. Wood ant behaviour inside a field ant nest has never been observed in detail before, let alone filmed. So what happens next must be interpreted with caution. There are fights and most wood ant queens are in fact killed at this stage. But after she has endured repeated attacks, some of the field ants become less aggressive towards her. Eventually, a confused field ant worker feeds the wood ant queen. And when it does that, the fate of the nest is sealed. The wood ant queen has now acquired the colony's scent. She oozes queenly pheromones and the field ants seem entranced by their new foreign queen. The gamble has paid off and she has a fully-functioning nest ready to receive her first batch of eggs. Taking over a nest of field ants is the way typical wood ants start a new family. But how about the queens from a supercolony with their multi-family communal nests? Have they found a more peaceful strategy? Each mated female has to set out on her own journey. If she's to become a true queen, she has to find a nest that will accept her. And that is where the tolerance of the members of the supercolony is tested once again. Being already in the heart of a supercolony, these newly mated queens don't have to walk far before encountering their own kind. But even for a supercolony queen, walking straight up to our busy trail is risky. If the workers she meets are not in a welcoming mood, they will tear her to pieces. Slowly, one-by-one workers come to investigate her. Some seem uncertain whether to attack or not, but others lick and clean her. After a few tense moments, a worker starts to drag her towards the nest. This is a sign that she will be adopted. And now scientists have made a further discovery. Many nests in the supercolony shortcut the whole process. The winged males and the queen ants don't even bother to leave the nest. Many different families live here. So there's no need to fly away to avoid inbreeding. The winged queens can simply mate with one of the males that hatched here. Perhaps this unusual behaviour is the next stage in the evolution of the supercolony. With these innovative mating systems, the supercolony queens don't take the same risks as normal wood ant queens. They don't need to infiltrate the nest of field ants to start a family. The workers just build new nests where needed, enabling the supercolony to extend deep into the forest where there are no field ants. It's changes in behaviour like this that most likely gave rise to the supercolony in the first place and colonises new habitat with all its riches. It's possible that this kind of cooperation between different nests is becoming more common among ants. New supercolonies are still being discovered in different species across the world. Are we perhaps witnessing the next stage of the social conquest of the earth? The supercolony consists of literally thousands of different families, all working in cooperation. It's a development that mankind achieved a very long time ago. And could be seen as one of the reasons why we have come to dominate so many parts of the planet. Could it be that peace is the winning strategy on this ant mountain, too?

Terrestrial Invertebrates

Terrestrial (land-dwelling) Invasive Invertebrates are animals that lack a vertebral column (backbone). Insects are the most common invasive terrestrial invertebrate, but it also includes other arthropods, molluscs (such as snails and slugs), and nematodes (roundworms).

Ecological Niches

how and where an organism makes its living -insects fill diverse, terrestrial, aeriel and freshwater ecological niches

Insect Dominance Powerpoint Notes

nsect dominance ENTO 2010E Insects and the Environment Instructor: Dr. Brendan Hunt Why Study Insects? Because insects are the dominant group of terrestrial animals on our planet! Dominance of Insects 1. Numbers of individuals 2. Biomass - total weight or volume of living organisms 3. Diversity a. taxonomic diversity b. ecological diversity Dominance of Insects 1. Numbers of individuals 2. Biomass - total weight or volume of living organisms 3. Diversity a. taxonomic diversity b. ecological diversity A 1-acre backyard in U.S. in summer may contain tens of millions of individual insects Abundance of insects (numbers of individuals)... Aphids on soybean leaf Abundance of insects (numbers of individuals)... 5000 - common number of clonal aphids on a single soybean plant during mid-summer Aphids on soybean leaf 5000 - common number of clonal aphids on a single soybean plant during mid-summer 1017 - number of individual ants (all species) alive right now (E.O. Wilson) [100,000,000,000,000,000] Abundance of insects (numbers of individuals)... Fire ants in their nest Dominance of Insects 1. Numbers of individuals 2. Biomass - total weight or volume of living organisms 3. Diversity a. taxonomic diversity b. ecological diversity The average biomass of all insects in an average 1-acre backyard in U.S. in summer is 600 pounds Biomass of insects The biomass of ants (Family Formicidae, Order Hymenoptera) in a Brazilian tropical forest is estimated to be four times that of all terrestrial vertebrates combined (E.O. Wilson) Oh my... Biomass of insects Bacteria Fungi Archaea Protists Viruses Kingdoms/Domains of Life Animals GT C: gigatons of carbon Plants dominate biomass among all life forms... 547 GT C total global biomass (>80%) Plants 450 GT C Biomass of life Biomass of life Kingdoms/Domains of Life Animals Plants 450 GT C (>80%) Bacteria Fungi Archaea Protists Viruses GT C: gigatons of carbon Plants dominate biomass among all life forms... 2.4 GT C (0.4%) 547 GT C total global biomass Animals (2.4 GT C) Annelids Fishes Arthropods (incl. insects, 1.1 GT C, 45%) Molluscs Livestock Cnidarians Nematodes Wild vertebrates Humans Plants dominate biomass among all life forms..., but insects and other arthropods dominate animal biomass Y. M. Bar-on et al. 2018. PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES 115:6506. Biomass of insects Dominance of Insects 1. Numbers of individuals 2. Biomass - total weight or volume of living organisms 3. Diversity a. taxonomic diversity b. ecological diversity Number of Number of Described Described Taxon Species Taxon Species 1. Bacteria, Archaea 4,800 11. Mollusca (Mollusks) 50,000 2. Fungi 69,000 12. Echinodermata (Starfish etc.) 6,000 3. Algae 27,000 13. Insecta 925,000 4. Plantae (Vascular Plants) 249,000 14. Non-insect Arthropoda (Mites, 5. Protista 31,000 Spiders, Crustaceans etc.) 124,000 6. Porifera (Sponges) 5,000 15. Pisces (Fish) 19,056 7. Cnidaria, Ctenophora 16. Amphibia 4,184 (Jellyfish, Corals, Comb Jellies) 9,000 17. Reptilia 6,300 8. Platyhelminthes (Flatworms) 13,000 18. Aves (Birds) 9,040 9. Nematoda (Roundworms) 12,000 19. Mammalia 4,000 10. Annelida (Earthworms etc.) 12,000 ≈45,000 verts. insects plants verts. other arthr. Size of individual organism figured represents number of described species in each major taxon ~1.6 million total species known to science Dominance of Insects 1. Numbers of individuals 2. Biomass - total weight or volume of living organisms 3. Diversity a. taxonomic diversity b. ecological diversity Ecological niche ‒ ecological role that a species fills in an ecosystem, or how and where an organism makes a living Major Classes of Niches Occupied by Insects 1. Terrestrial niches ►on or in soil, plants, decaying organic matter, other animals, constructed nests 2. Aerial niches ►collecting food (e.g., aerial predation & flower visitation), mating, and dispersing on the wing 3. Aquatic niches ►puddles, tree holes, ponds, lakes, streams, rivers, tidal marshes, hot springs, farm runoff ponds Major Classes of Niches Occupied by Insects 1. Terrestrial niches ►on or in soil, plants, decaying organic matter, other animals, constructed nests 2. Aerial niches ►collecting food (e.g., aerial predation & flower visitation), mating, and dispersing on the wing 3. Aquatic niches ►puddles, tree holes, ponds, lakes, streams, rivers, tidal marshes, hot springs, farm runoff ponds Ecological niche ‒ ecological role that a species fills in an ecosystem, or how and where an organism makes a living Major Classes of Niches Occupied by Insects 1. Terrestrial niches ►on or in soil, plants, decaying organic matter, other animals, constructed nests termite nests in Argentina termite nests in Australia fire ant nests in southern U.S. Major Classes of Niches Occupied by Insects 1. Terrestrial niches ►on or in soil, plants, decaying organic matter, other animals, constructed nests 2. Aerial niches ►collecting food (e.g., aerial predation & flower visitation), mating, and dispersing on the wing 3. Aquatic niches ►puddles, tree holes, ponds, lakes, streams, rivers, tidal marshes, hot springs, farm runoff ponds Ecological niche ‒ ecological role that a species fills in an ecosystem, or how and where an organism makes a living Major Classes of Niches Occupied by Insects 1. Terrestrial niches ►on or in soil, plants, decaying organic matter, other animals, constructed nests 2. Aerial niches ►collecting food (e.g., aerial predation & flower visitation), mating, and dispersing on the wing 3. Aquatic niches ►puddles, tree holes, ponds, lakes, streams, rivers, tidal marshes, hot springs, farm runoff ponds Ecological niche ‒ ecological role that a species fills in an ecosystem, or how and where an organism makes a living Major Classes of Niches Occupied by Insects 1. Terrestrial niches ►on or in soil, plants, decaying organic matter, other animals, constructed nests 2. Aerial niches ►collecting food (e.g., aerial predation & flower visitation), mating, and dispersing on the wing 3. Aquatic niches (mostly freshwater) ►puddles, tree holes, ponds, lakes, streams, rivers, tidal marshes, hot springs, farm runoff ponds Insects are largely missing from one major biome or class of niches.... small size of many insects allows them to occupy niches not available to larger animals... "Leaf miner" feeding trail Parasitoid wasps emerging from host (stinkbug) eggs Colony of ants in acorn 1mm Dominance of Insects A. Numbers of individuals B. Biomass - total weight or volume of living organisms C. Diversity 1. taxonomic diversity 2. ecological diversity Because of their dominance in numbers, biomass, and diversity, insects play important ecological roles... Major Ecological Roles of Insects A. Pollination of many flowering plants B. Herbivory (important consumers of primary producers) C. Predation or parasitism of other insects D. Decomposition E. Soil conditioning F. Serve as food for other animals Major Ecological Roles of Insects A. Pollination of many flowering plants B. Herbivory (important consumers of primary producers) C. Predation or parasitism of other insects D. Decomposition E. Soil conditioning F. Serve as food for other animals 500 million tons of insects consumed annually by birds alone! Because of major ecological roles they play, insects are essential to functioning of biosphere..

EO Wilson on Ant Chemical Communication

Wonders how ants organized their intricate societies This was a question that fascinated him so much Deduced that ants had a special type of communication but did not know what it was Wonders how they communicate when there is food around performed dissection on ants (fire ants) to see what it was on a biological and chemcial level that helped them communicate came across the dofour's gland part of the ant's anatomy Discovered over 20 different pheromones, the chemical signals through which ants talk to each other ants not only use pheromones to communicate but they have a pheremonal langauge

Bears and the Bees

the cub is shut down by the bees trying to get the honey but the mother has just enough success to get ONE honey comb. since the mother bear destroyed the colony for the bees, their potential offspring will die since it is exposed to the environment the bees must now work to make sure they survive and build a new colony by feasting on their own honey so it can be stored

ecological diversity

the number of ecological roles filled by insects

Medical Entomology

Today's lecture in Insects and the Environment is on the topic of Medical Entomology. I'm Brendan Hunt. The primary health risk introduced to humans and livestock from insects and other arthropods is the transmission of disease. Although there are also some health risks associated directly with feeding and with venom. In this lecture, I will focus on the role of insects in vector-borne diseases. A vector is an organism that transmits a disease. The disease itself is caused by transmitted bacteria, fungi, viruses, or parasites. In this context, the human is the host which interacts with the vector, such as a mosquito. There are over 1 billion cases of vector-borne diseases in humans each year, with over 1 million deaths, accounting for 1/6th of worldwide disability and illness. Most arthropod vectors of disease come from the insect order Diptera, which includes mosquitoes, black flies, sandflies, biting midges, horse flies, eye gnats, blow flies, flesh flies, house flies, and tsetse flies. Other insect vectors include the kissing bug, lice and fleas. And among non insect arthropods, ticks are particularly significant vector of human disease. Mosquitoes are, without a doubt, the most problematic vectors from a human health standpoint. Mosquito life cycles consist of an aquatic larval and pupal stage, followed by an aerial adult stage. Adult females require a blood meal to produce eggs, and once laid, eggs can withstand long drying periods. There are many, many different species of mosquitoes and not all are known to carry human diseases. But those that do carry disease represent the world's deadliest animals to humans. Malaria is one of the most deadly diseases in the world. It's vector includes 30 to 40 species of mosquitoes from the genus Anopheles, including those that live in the US. However, the Plasmodium parasite that causes malaria is currently absent in the US, which is why malaria is not commonly seen here. Another problematic genus of mosquito is Aedes, which contain species that are vectors of several viruses that cause disease in humans, including Dengue, Zika and West Nile virus. Another important disease vectored by insects is known as Human African trypanosomiasis or sleeping sickness. The vectors of this disease are tsetse flies. A similar protist parasite to sleeping sickness causes Chagas disease, which is transmitted in this case by vectors known as kissing bugs. Typhus is a disease caused by bacteria that have diverse arthropod vectors, including body lice, fleas and mites. Lyme disease is caused by a bacteria that is transmitted to humans by the bites of infected ticks. I've selected four videos to accompany this lecture. The first discusses Silent Spring in the context of malaria and whether the banning of DDT was warranted. The second video describes the importance of medical entomology to disease management. The third video describes a trial in which mosquitoes were inoculated with bacteria that confers resistance against dengue. And the final video for the module describes how a line of mosquitoes were engineered and released to impede mosquito reproduction in the wild. I hope you've enjoyed this final lecture and all the other lectures for insects and the environment this semester.

Dawson Bees

Large bees... male bees are violent and fight each other for death the goal is to survive long enough to reproduce.... all the male bees end up dying because of fighting

The exoskeleton

A body covering, typically made of chitin, that provides support and protection It is outside the body for insects Different from humans because their skeletons are on the inside

The master of chemical warfare

Bombardeir beatle Creates a chemcial reaction that is very violent and produces a boiling caustic liquid that explodes

E.O Wilson

Biologist who co-coined, with Robert MacArthur, the theory of island biogeography, which identifies factors that regulate species richness on islands. Estimates that the total number of individual ants of all species combined is ten to the 17th. Humans have a population under 10 to the 10th

EO Wilson

Biologist who co-coined, with Robert MacArthur, the theory of island biogeography, which identifies factors that regulate species richness on islands. ants is the center of his life 16,000 kinds of ants estimate 10k trillion ants in the world the weight of all ants combined=weight of all humans combined

Taxonomy and Phylogentics

Today's lecture in Insects and the Environment is on the topic of Taxonomy and Phylogenetics. I'm Brendan Hunt. Taxonomy is the science and practice of classifying living organisms. As Confucius said, "the beginning of wisdom is to call things by their right name." Taxonomy involves recognizing, describing, and naming species, which are classified into a ranked system that aims to reflect evolutionary history. Taxonomic classification of species involves a nested hierarchy of groupings from larger to smaller groups. Insects and humans both belong to the kingdom Animalia. But insects and humans are in different phyla. Insects are in the phylum Arthropoda and humans are in the phylum Chordata. The class Insecta is synonymous with the term insects. All species that belong to the class Insecta are insects. And all insects belong to the class Insecta. Within insects, there are 30 or so major groups called orders, most of which you will learn about in the next lecture. Orders are split into smaller groups of species called Families, which are further split into genera. And finally, species level designations are made. Each species has a scientific name known as a binomial, which is written as the genus and species in italics with the genus capitalized and the species in lowercase. The example shown is Romalea guttata, which is known by the common name Eastern lubber grasshopper, Romalea guttata belongs to one of the grasshopper families called Romaleidae, which belongs to the order Orthoptera. Orthoptera is a group comprised of grasshoppers, locusts, and crickets. But what is a species exactly? The answer to this seemingly simple question can be challenging to pin down. Species consist of individuals that interbreed with other individuals from the same species and evolve independently from other species. One of the most common species concepts is called the biological species concept. It is a somewhat conservative approach to species classification in that it requires a complete lack of interbreeding between species and thus errs on the side of joining rather than splitting species. According to the biological species concept, if populations of organisms do not interbreed regularly in nature, or if they fail to produce fertile offspring when they do, they are considered separate species. The biological species concept confirms a complete lack of gene flow, which is the transfer of genes through sexual reproduction between species. This ensures the species evolve independently from one another. The biological species concept has been widely accepted since it was championed by Ernst Mayr in 1942. And it serves as the legal definition employed in the US Endangered Species Act. The criteria for species designation can be difficult to test if populations do not come into contact. And the biological species concept does not apply to asexual organisms, including all bacteria. Because of this, scientists often use multiple criteria, including morphological and genetic information to classify species. An evolutionary tree represents a hypothesis about the history of descent with modification from an ancestral species. In order to understand evolutionary trees, you need to understand that current species are not descendant from each other. Rather, they are descended from a common ancestor. For example, humans are not descendants of chimpanzees. Rather, they are two descendant species that split from an ancestral species that no longer exists. Evolutionary trees are known also as phylogenetic trees or simply as phylogenies. Evolutionary trees are produced from a particular dataset analyzed with a particular technique, such as comparisons of observable traits or DNA sequences. Evolutionary trees do not show everything and hypotheses for species relationships can change over time or with analyses of different datasets. As a next step in furthering your ability to interpret evolutionary trees, let's take a look at their key features. Each solid black line in this tree is called a branch. The horizontal branches in the tree shown can depict information with their lengths, but the vertical branch lengths are always arbitrary with the simple purpose of spacing out the horizontal lines for readability. The terminal branches on this tree are those that connect to boxes on the right of the tree. These red boxes are called the tips or terminal nodes of the tree. Each of these boxes represents a current observable species, group, or individual. The internal branch points on the tree are called nodes. These represent hypothetical common ancestors of branches that extend to the right as estimated based on the observed data at the tips of the tree. The root of this tree is the hypothesized ancestor of all nodes in the tree. It is shown as the gold box to the left of the node numbered 1. From left to right, this tree represents the progression of evolution from more ancient to more recent time. The advent of new features and a lineage referred to as transitions are indicated by vertical tick marks on the tree. To better appreciate the information conveyed by a tree, let's take a look at an example of a phylogeny of cat species. In this case, each terminal node or tip of the tree shows a currently living species of cat. Notes that are branch points for terminal branches, like node six, represent the hypothesized most recent common ancestor of the connected tips. Terminal branches joined by a node are said to represent sister taxa. The term taxa can refer to species, populations, or other groups. If we look at node five, we see what is referred to as a polytomy, where more than two branches connect to the same node. In this case it is unresolved which two of these three species are most closely related to one another. This phylogeny is based on observable traits. In this case, coat markings. Transitions and coat markings are depicted with vertical tick marks and groupings are established by the presence of shared and different traits. Let's take a closer look at the logic underlying how phylogenies are constructed from trait data. To do so, we consider an ideal case, meaning the data conform to specific assumptions that may not always be met in reality. In the ideal case, we have knowledge of a common ancestor's characteristics. Each evolutionary novelty or derived character has arisen only once during the course of evolution. And finally, no derived characters were subsequently lost. When these assumptions are met, we can work backwards from unique traits to those shared by larger groups of taxa to construct a tree that accurately represents their evolutionary relationships. This approach works because descent with modification from common ancestors produces species displaying nested sets of shared novelties. Here we start with the unique traits of the long bill and dark tail. Since we can assume in this ideal case, these are unique derived traits, we can mark each of these traits as occurring on a terminal branch connected to only one species. The next most common trait is the presence of orange wing tips. Two species share this derived trait, so the transition is marked as occurring before their most recent common ancestor. That is before the node that joins the two species that have this trait. The shared presence of this trait causes the two species to be characterized as sister species in our phylogeny. Next, three of the four species have an orange mask. So the branches leading to the three masked species are joined by a node. And the transition to mask presence is marked by a tick mark before the descendant lineages that carry the trait split from one another. Finally, all of the currently living species in the tree have a tail bar, so they can all be joined by a final node that connects to the root of the tree. Evolutionary trees are depicted in many styles, but each of these trees conveys the same relationships. Evolutionary relationships in each case are depicted solely by the order of branching in the tree. The principles of phylogeny construction in the ideal case give you an understanding of the underlying logic behind tree construction. But tree construction is often complicated by violation of ideal assumptions in the form of convergent evolution and reversal. Convergent evolution is the independent appearance of similar derived characters in different lineages. Reversal is the loss of a derived trait in a lineage, resulting in a return to an ancestral condition. The similarity and traits caused by convergence and reversal is collectively known as homoplasy. Due to homoplasy, analysis of many independent traits is often required for tree construction. One way that biologists resolve ambiguous relationships between species is to assess the relative similarity of DNA sequences from many different genes. The taxonomic classification of insects serves as an important information storage and retrieval system, as well as a guide to the relationships among species. As a result, taxonomy can be used as a roadmap to understand major patterns of evolution in the insects. Let's return to the Eastern lubber grasshopper. This phylogeny shows the Eastern lubber along with several other insect species. Based on the tree, we can determine which species are most closely related to the Eastern lubber, meaning which diverge from a common ancestral species shared with the Eastern lubber most recently during the course of evolution. In this tree, the sister species of the Eastern lubber is the Western lubber, which belongs to the same genus. We can also see that a cone headed grasshopper belongs to a different family. One that also includes the meadow katydid. So the cone headed grasshopper is actually a closer relative to the meadow katydid than to the Eastern lubber grasshopper. Several species shown on this tree belong to different orders of insects. These shared a most recent common ancestor with the Eastern lubber hundreds of millions of years ago. In this phylogeny of all the insect orders, we can see some of the higher level groupings that correspond with major innovations during the early evolutionary history of the insects, including metamorphosis and wing folding. In the next lecture, I'll introduce you to each of the major insect orders as an overview of insect species diversity and evolutionary innovation within the group.

Biodiversity Lecture

Today's lecture in Insects and the Environment is on the topic of biodiversity. I'm Brendan Hunt. Biological diversity or biodiversity is the number and variety of species in any locality, ecosystem, region, or even the entire biosphere. The most common metric associated with biodiversity is species richness, which is simply the number of species present. A slightly more sophisticated measure of biodiversity is species density, which captures both the number of species per unit area and the population density of each species. E.O. Wilson coined the term biodiversity to remind us how little we know about the natural world and of the danger that we destroy it before we even know it's there. Insects are particularly biodiverse. Over half of the described species on the planet are insects. And it's estimated that only around 20 percent of insect species in existence have been described. Patterns relating to species abundance have contributed importantly to the development of ecology. In particular, once broad patterns in nature are discovered and the mechanisms driving the patterns are defined, together, they form the basis for theory, which is an empirically and factually based mechanistic explanation. Macroecology characterizes and explains statistical patterns of abundance, distribution, and diversity. Macro ecological patterns can be detected when large sets of species are studied over large spatial scales or over long time periods. Early discoveries related to species diversity identified patterns associated with latitudinal gradients over space and ecological succession over time. Patterns of succession and species richness on islands as assessed by extermination and recolonization studies form the basis for McArthur and Wilson's theory of island biogeography, published in 1967. The theory examine the relationships among species number per island, the size of the island, and the distance of the island from the mainland source of colonists. As shown in the graph at right, rapidly dispersing species cause a high species immigration rate initially, which then slows as slower dispersing species arrive until ultimately reaching 0. In contrast, the species extinction rate increases exponentially with the number of species present. Due to the increased likelihood that chance extinction events will occur, or due to pressures from increased competition and natural enemies. The equilibrium number of species is the number that is predicted to be stably maintained based on associated immigration and extinction rates. Islands size serves as a gradient that shapes the equilibrium number of species, with larger islands supporting a higher equilibrium number of species. A second gradient of biodiversity is that of island remoteness. The distance of the island from the source of colonists, or mainland, influences the number of equilibrium species. Because rates of immigration are higher on near islands than far islands, as shown in the graph at right, the size and remoteness gradients in island biogeography theory predict the equilibrium numbers of species will be higher on relatively near large islands than on relatively far small islands. The principles of island biogeography theory apply not only to islands formed by land and bodies of water, but also by mountains among lowlands, the presence of a specific host plant, and habitat patches among developed areas. This gives island biogeography theory relevance to conservation planning. Another long known gradient of biodiversity is shaped by latitude or distance from the equator. Species richness increases moving from the Arctic or north temperate latitudes to the Equator, as shown in this figure for Swallowtail butterflies. What factors cause the latitudinal gradient in biodiversity? One key factor may be that the tropics make up the largest landmass of any biome type, and this area is contiguous from North to South. In the tropics, similar temperatures are also present over a wide band of latitude. Other key factors that are likely to influence the latitudinal biodiversity gradient are the warm and wet conditions that lead to high productivity in the tropics, climatic stability, the presence of diverse habitat types, the presence of intense competition, and the old age of tropical ecosystems. Other known gradients in species richness include altitudinal gradients, wherein the cooling effects with increased altitude translate to rapid climate change as one moves up a mountain. This leads to lower biodiversity at high elevations. Time gradients are observed during ecological succession and disturbance gradients are driven by factors such as wind, flood, fire, erosion, herbivore outbreaks, and Human Development. Interestingly, the intermediate disturbance hypothesis suggests that diversity is actually highest when disturbances are intermediate in frequency and intensity. This is because this creates an ideal mosaic of habitat types to foster biodiversity. The theory of island biogeography is relevant to the conservation of biodiversity. Because as areas of natural vegetation decline, we can employ the theory to predict the associated decline in biodiversity based on general species-area relationships. For example, EO Wilson predicted that in general, a 50 percent loss of species may be expected with a 90 percent reduction of islands size. In the graph at right, a point estimate extrapolates how big a habitat patch may need to be to support 26 species of butterflies based on observed patch sizes that support between 1 and 22 species. But such extrapolation may not be reliable. When it comes to conservation of biodiversity, it may be that fewer large areas of habitat are superior to many smaller areas of habitat. This is due to several factors. First, smaller individual populations have a higher chance of extinction than one large population. Second, the edges of a habitat may be less suitable than the interior, though some species specialize on these transitional or disturbed areas. Some of the deficits of having small habitat reserves can be countered by connecting patches with corridors that allow the movement of species.

Insect behavior

Today's lecture in Insects and the Environment is on the topic of insect behavior. I'm Brendan Hunt. The essential ingredients of life are organization, metabolism, development, reproduction, interaction with the environment, and genetic control. Each of these elements is influenced by interactions with other organisms and the abiotic environment. Life requires reproduction of one's own kind to persist, and the metabolism, development, and growth prior to reproduction will depend on successful foraging and feeding behavior. Finding mates, mating, and reproducing also often require complex behavioral sequences and diverse strategies. Behavior can be defined as anything that an individual does during its life involving action and response to a stimulus. Eating behavior is stimulated by hunger. Sleeping or resting behavior is a response to fatigue. Escape is a response to attack. And reproductive behavior occurs in response to physiological urges and stimulation by potential mates. Much of our understanding of how behaviors evolve results from studying how species are adapted for survival and reproduction. And each developmental stage of a species may experience its own kinds of problems and opportunities. Some behaviors are innate, meaning their instinctual and inherited, while others are learned, even in insects. But just observing a behavior does not prove that it was done to achieve a particular result or was done for a particular reason. Experimental manipulation of an insect or its environment can provide evidence to support hypotheses about behavior. Fortunately, there's a long tradition of ethology, the study of behavior, in insects from which we can draw insights. One of the founders of the field of ethology was Nicholas Tinbergen, a Dutch ornithologist. Tinbergen proposed four basic questions that should be helpful to understanding how and why members of a species exhibit a specific behavior. First, what triggers the behavior and what body parts, functions, and molecules are involved in carrying it out? Second, is the behavior present early in life or does it change over the course of the organism's lifetime? And what experiences are necessary for its development? Third, how does the behavior affect an organism's chances of survival and reproduction? And fourth, how does the behavior compare to those of related species? Why might it have evolved as it did? Ethology has revealed that many behaviors are adaptive responses to the challenges insects must face in order to survive and reproduce. Seasonal migration is an adaptive behavioral strategy because it results in abundant resources and avoids severe weather. Before undertaking migrations, which usually consist of unidirectional and persistent flight in insects, individuals are likely to store energy as fat and suppress egg production. Seasonal migration is performed by some dragonflies, some aphids, some leafhoppers, butterflies, moths, beetles, flies and ants. Another challenge that insects, like all animals, must face is procuring food for survival. Indeed, much of ecology concerns the behaviors involved with food, feeding, and foraging. Foraging behavior is defined as searching for food for oneself or one's offspring. Foraging usually involves a series of decisions based on stimulus-response. The adaptive tuning of chemical or visual senses may be implicated. And foraging decision-making can involve associative learning. For example, insects may learn to associate cues with the presence of food or may follow a daily route based on past success. Insects may also have to make decisions about when to move from one area to another in order to effectively forage. Finding a safe place to live is a challenge that has shaped numerous, diverse insect behaviors. Adaptive behaviors of this type include constructing or inducing habitats, provisioning cells in which larvae feed, using a plant or animal host as a protective microhabitat, making a nest, and burrowing into the substrate. Reproduction can also present diverse challenges, from finding a mate to laying eggs in the right place. Individuals vary in their success at mating, which contributes to fitness differences through a form of natural selection known as sexual selection. Insects may attract mates from long distances by calling with auditory or chemical signals. In closer proximity, they may use visual cues for attraction, or may even use taste to verify who they're mating with. When there are differences in the form or behavior of males and females of a species, this is known as sexual dimorphism. Sexual dimorphism can involve traits that appear to decrease an individual's chance of survival. When sexual dimorphism is driven by sexual selection on courtship displays, dramatic traits akin to a peacock's tail often result. Sexual dimorphism can also be shaped by natural selection on survival. For example, if males and females exploit different resources. And sex specific functions like egg-laying also shape sexual dimorphism. In the case of the hollyhock weevil, females have elongated snouts so that they can bore holes into buds of a host plant prior to oviposition. The reproductive success of males and females are often shaped by different factors. This occurs because eggs are energetically expensive and thus in finite supply. Eggs have a large amount of stored energy and nutrients for the developing embryos, in contrast to a male sperm, which is little more than DNA with a propeller. A female insect's reproductive success will generally be limited by the number of eggs she can lay, whereas a male's reproductive success is likely to be limited by the number of females he can mate with. When male reproductive success is limited by the number of mates, they tend to compete with other males for access to females. This is known as intrasexual selection. When female reproductive success is limited by investment in eggs or parental care, they will tend to be choosy when accepting male mates. This is known as intersexual selection. Intrasexual selection involving male-male combat over access to mates can favor morphological traits that include large body size, weaponry, and armor. And if a female mates with two or more males, as occurs in many species, the male whose sperm reaches the most eggs has the highest reproductive success. In damselflies, males use a special structure to scoop out sperm from prior mates. Other male strategies to maximize reproductive success when females mate multiply include guarding, prolonged copulation, and insertion of copulatory plugs. Males of many species compete with other males for female acceptance by advertising to females with elaborate displays and courtship rituals. Finally, males may compete with other males by providing nuptial gifts to females. As shown here, female hanging flies choose to copulate longer with males that provide her with a sufficiently large prey item. So why bother with all the trouble involved in sexual reproduction? In short, sexual reproduction is heavily favored over asexual reproduction by natural selection under most circumstances. This is because sexual reproduction increases genetic diversity. This helps provide variation that can help a population adapt to changing environmental conditions. In contrast, if a population were clonally produced, a rapid or unexpected change would be more likely to lead to localized extinction. There are three videos on ELC that accompany this lecture. The first is a short video of the remarkable mating dance of the peacock spider. The second is a short video about a species of firefly native to the Great Smoky Mountains that synchronizes their flashing to attract mates. And the final video is another episode of The David Attenborough series, Life in the Undergrowth. This one is a bit of a departure in that it primarily features spiders, our non-insect arthropod friends. But the episode nevertheless features a broad array of complex behaviors that take advantage of silk. The episode also features a couple of examples of courtship behaviors in action.

Insect Diversity: The Orders

Today's lecture in Insects and the Environment is on the topic of insect diversity. Today, we'll take a look at the major groups of insects called orders. I'm Brendan Hunt. As discussed in the last lecture, taxonomy provides a mechanism to group species into a hierarchy of increasingly larger groups based on evolutionary relationships. Species are grouped into genera (the plural of genus), which are grouped into families, which are grouped into orders. Orders are the largest major taxonomic groups of insects, There are 30 or so insect orders, but the orders differ widely in the numbers of species that belong to each group. This pie chart is a rough visual estimate of the numbers of species in each insect order. Five orders contain around 90% of all insects species and deserve our special attention. They are the Lepidoptera, which are butterflies and moths, Diptera, which are flies and mosquitoes. Hymenoptera, which are bees, ants and wasps, Coleoptera, which are beetles, and Hemiptera, which are true bugs. In this lecture, we'll go through this phylogeny of 20 insect orders and introduce each in turn. Four key evolutionary innovations are denoted on the tree with boxes and text. These innovations are estimated to have arisen hundreds of millions of years ago and are present in most or all of the descendant orders that diverged subsequently. The first two orders in our tree, *struggling to pronounce* ... Microcoryphia and Zygentoma were the earliest to diverge during insect evolution. Both of these orders lack wings and the young look just like miniature versions of adults. These are known as a ametabolous. Over 400 million years ago (*estimate*), the lineage leading to the zygentoma and other insect orders we will discuss evolve double hinged mouthparts. Double hinged mouthparts offer additional strength and maneuverability, which helped to facilitate the exploitation of more diverse diets in the groups with this trait. The second key adaptation during early insect evolution was the advent of wings in adults, which arose as a trait prior to the evolutionary divergence of the remaining 18 insect orders on our tree. The advent of flight was immensely important, allowing insects to efficiently travel to resources, to migrate, to disperse, and to exploit new ecological niches. Because immature stages of winged insects lack wings, the juveniles don't look exactly like adults. The next 11 orders in our tree undergo what is known as incomplete metamorphosis. During development, the immatures still look similar to adults, but only the adults have wings. So the adult appearance differs from the immatures. The insects that develop in this manner are referred to as hemimetabolous, with immature stages referred to as nymphs. The first hemimetabolous order in our tree is the order Odonata, the dragonflies and damselflies. These charismatic fliers do not fold their wings and the order contains around 6 thousand described species. Immature stages are shown above each adult. The order Ephemeroptera contains the mayflies, with around 3000 species. Mayflies have massive matings harms, as you will see in the episode of the series 'Life in the Undergrowth' featured in this course module. The Odonata and Ephemeroptera cannot fold their wings over their back, which brings us to a third key innovation during insect evolution. Wing folding. Wing folding allows insects to protect their wings and fit into small places. The ability to fold wings over the back of the insect arose before the divergence of the remaining orders in our tree. The orders that branch after this point can be referred to as a group of orders. As a result, this group is known as the Neoptera. The first order in our tree with wings folded over the back is the Dermaptera, commonly known as earwigs. These unfortunately named insects don't favor ears. They eat dead or decaying matter and exhibit maternal care of their young. How sweet? The Plecoptera are stone flies. Stone flies are often used as bait for fly fishing and they are used as bioindicators because of their low tolerance of pollution. The order Orthoptera contains grasshoppers, katydids, and crickets, with around 24 thousand described species, many orthopterans sing to attract mates who hear through their legs. The order Phasmatodea contains walking sticks. These masters of disguise look like sticks or leaves and even lay eggs that look like plant seeds. The order Mantodea contains mantids and mantises, which have raptorial forelegs used for hunting. Some have excellent disguises like this orchid mantis pictured at right. The order Battodea contains both cockroaches and termites. Most cockroach species are actually not urban pests. They're forest floor dwellers. Termites used to be regarded as their own order, but the order was joined with Blattodea when genetic evidence demonstrated that termites evolved from wood dwelling roaches. Termites are highly social and can exist in very high numbers, playing an outsize role in many ecosystems. The next three orders have mouthparts modified for piercing and sucking fluids from plants and animals. The order Thysanoptera, known as thrips, have mouthparts that form a straw that sucks contents out of plants. Many thrips species carry plant viruses acting as impactful agricultural pests. The order Hemiptera, known as the true bugs, has around 100 thousand species and is one of the top five most speciose orders of insects. When an entomologist uses the term bug, they often mean a hemipteran, rather than an insect in general, The hemipterans have hemielytra, meaning half of their outer wings are hardened. Groups of species of hemipterans include stink bugs, leafhoppers, cicadas, and aphids. The order Phthiraptera is composed of lice, such as book lice that can eat glue, an old book bindings, and lice that live on humans. This brings us to a fourth key evolutionary innovation that arose during the course of insect evolution. The origin of complete metamorphosis. Complete metamorphosis is exemplified by the lifecycle of butterflies. The immatures, called larvae, look very different from the adults. Wings begin to develop inside the bodies of the larvae and a dramatic transformation occurs during the pupal stage from which adults emerge with wings. Insects that undergo complete metamorphosis are referred to as holometabolous, including the four most speciose orders of insects. The remaining orders in our tree are all holometabolous. The order Hymenoptera includes the ants, bees, and wasps. With over 150 thousand described species. Hymenoptera is one of the five most speciose orders. Many Hymenopterans are eusocial, meaning that they have effectively sterile workers and live in cooperative groups like honey bees. Many other hymenopterans are parasitoid wasps that lay eggs in insect hosts. The order Neuroptera includes insects known as lacewings and antlions. The order Coleoptera is the most speciose (species-rich) order of insects. These are the beetles and there are around 390 thousand described species. Adult beetles have a heavily armored outer set of wings known as elytra. The order Diptera is known as the true flies. With around 160 thousand species, Diptera is one of the five most speciose orders. Adult dipterans have only one pair of wings, unlike most insects, and mosquitoes belong to the group, making them flies. Mosquitoes are a major source of disease in humans, carrying parasites that cause malaria and other diseases. The order Siphonaptera is comprised of fleas, which lost their wings and feed on vertebrate animals like our pets. Fleas are another source of disease transmission in the insect world. The order Trichoptera contains caddisflies, which in some species have immature stages with some serious bling that can even be used for jewelry making. And last but certainly not least in our tour of the insect orders is Lepidoptera, the butterflies and moths, with over 160 thousand species. These well-known and charismatic insects make up one of the five most speciose orders. The terms caterpillar and chrysalis are lepidopteran names for a larva and pupa. I hope this your has given you a taste of the remarkable diversity of insects on the planet. The placement of four key innovations on our phylogeny shows how the presence of these innovations can be used to group living species and how these innovations have influenced the diversification of descendant groups. Indeed, taxonomy can be used as a roadmap to understand major patterns of evolution in the insects.

Insects are successful at occupying diverse niches

because of their small size: allows insects to occupy niches not available to other aniamsl