SciCafe: The Surprising Lives of Insects

SciCafe: The Secret Lives of Insects - Transcript Marlene Zuk (Behavioral Ecologist, University of Minnesota): I was just talking to the teens in teen SciCafe, which was super fun and I started out asking them how many of them—I actually turned my back and I said raise your hand if you don't like insects or are afraid of them. And there was actually kind of a lot of hands. I know this because I had a spy in the audience and there were a lot of them. And so I'm hoping that maybe some of you don't necessarily feel the same way. Although, I'm going to start out talking about something that is maybe familiar to all of you. It turns out that people are more afraid of insects than they are of dying. At least this was from a poll back in the 1970s in which people were asked what is your greatest fear. And it turns out that public speaking and heights exceeded being scared of insects as sources of fear. And dying came in at number six. So, you realize that when you work on insects, you're kind of operating in—you're coming in from behind, which can be a little bit of a problem. But at the same time, those of us who work on insects realize that scientists have been studying them and coming back to them to answer questions about our planet for centuries. And I'm really interested in partly why that is. I mean, some of it is just the sheer magnitude of almost everything about insects; they're more numerous than almost any other animal, they make up over 80 percent of all species. There's estimates of the number of kinds of insects. They vary all over the place. New ones are being discovered all the time. There are at least a million, possibly as many as 10 million species of insects. This means—just to put this in perspective—that you could have an insect-of-the-month calendar and you would not need to reuse a species for well over 80,000 years. So, take that pandas and kittens. I mean, I feel like this is a big triumph. And part of what I love about—and so I do find all that interesting, but part of what I really love about insects is that I think they show us a really different world and a way to understand how life can solve the same questions in many, many, many different ways. I mean, think about it. They show us that you don't really need a big brain to do big things. Because insects do a lot of the things that people seem to do. They meet. They mate. They fight. They break up. They get back together. They have babies. They raise them. But they do this in ways that are completely different than the way we do because they lack anything approaching the kind of nervous system and brain that humans or any mammal or any vertebrate has. And so I think they force us to reexamine a lot of our assumptions about the way the world works and about what's natural and what's normal about living things. And there's no place where that's more obvious, I think, than when you look at some of the social insects; the ants and the wasps and the bees. And this is an ant worker that's guarding the nest entrance to her colony. And I want to just dwell for a minute on how cool I think ants are by reading you something from my book, which says that when I was a child I went through a phase in which I told people I wanted to be a myrmecologist when I grew up. And, although, I did indeed spend time watching the ants in our backyard, along with the other insects, I was probably driven more by being smug at knowing that the word means someone who studies ants than actually by any career goal. But be that as it may, when we had an assignment in third or fourth grade to read a book and report on it to the rest of the class, I choose a book on ants and I happily launched into a litany of their amazing behaviors. Ants, I proclaimed, made gardens of fungus that they harvest for food. They stored honeydew in their massively swollen abdomens and fed it to the other workers droplet by droplet. I mean, not only that, I cheerfully told my classmates who were by that point probably unnerved, if they were not simply bored, but army ants could swarm through entire jungle villages, consuming every living thing they encountered by tearing it to pieces. Cows, pigs, chickens and people all were subject to the advancing hordes with their bladed jaws. If one were caught unawares by the oncoming troops, the only recourse was to set one's bedpost in saucers of kerosene, get under the covers and pray the ants didn't find a way to drop down on to the bed from the ceiling. I was slightly hampered in my explanation of this dire state of affairs by my uncertainty of exactly what kerosene was. But I was sure that if I lived in an area that was frequented by army ants, I would be able to procure some. Now, so here my teacher intervened. Surely, she said, you are exaggerating. Ants could not possibly be that destructive. Perhaps they attack the animals near an area or got into a hut or two, but the scale of devastation and carnage seemed a bit much for such tiny creatures. I dug in my heels. No, I insisted, the book had said—and, hence, I unswervingly believed—that the ants could tear apart a person in minutes. It wasn't just the odd chicken or two. it was an entire village. And I honestly don't remember the outcome of this disagreement or if my grade on the book report was reduced because my teacher was suspicious of what I was saying, but the real point here is that from a very young age I've been surprised at how people just don't really understand how amazing the behaviors of insects are. And part of that is that I think when we look at insects, we look at insects and we see them as if they're tiny people. And we try to make them into little images of ourselves. When in fact, by doing that, in a way we're cheating ourselves. And there's nothing that illustrates this as well as looking at the way people talk about sex and the social insects. So, I don't know how many of you have seen Bee Movie. The teens just told me apparently it's having a resurgence on the Internet. I did not know this, but apparently it is. And so in case you missed that, Jerry Seinfeld plays this slacker honeybee who is yearning for a life outside the drudgery of the hive. And the portrayal of a worker social insect, whether it's an ant or a bee or a wasp or what have you, as being a male is as ubiquitous as it is inaccurate. Now, probably most of you here know that all of the bees that you see flitting from flower to flower, all of the ants that are going into your sugar bowl or finding your picnic, all the wasps that are bothering you if you're trying to enjoy a nice summer day, all of the social insects that you're likely to see are female. I'd be willing to bet that unless there are beekeepers in the audience, nobody's ever seen a male social insect. And, yet, everybody always refers to them that way. And so in doing this we're not alone. People have been keeping bees certainly for a millennia and, yet, they were confused about the sex of the bees and how reproduction worked in them for a long, long time. And some of that happened because they just assumed that everything was like people. Arab cultures thought, okay, maybe the colony is like an army where you've got a military organization, so you've got soldiers, which of course would have to be the workers because they're the stingers; they have weapons. They assumed that nothing that had a weapon could possibly be a female. Aristotle tried to reason out the problem, but he ran into difficulty because if the stinging bees, which are the workers, were going to be male, then that would have suggested that the drones, which people at the time knew about—so, those are the males, and they just kind of lie around in the hive until it's time to go out and mate—that the drones were female and he was unable to accept the idea that the males in the society did all the work of taking care of the young. So, he eventually concluded that bees might have the organs of both sexes in a single individual, which is actually not that farfetched because that is true of some animals, as in a lot of plants. But then he was further flummoxed by the lack of reproduction on the part of any individual, but the queen or—what he called it—the leader. And it actually took until the very late 1600s until people finally figured this out. And so here in the slide you can see at the top that's a worker honeybee. She's female. That's the one you always see. In the middle is a queen. She's larger. And at the bottom is the male, the drone. He has really large eyes and all he ever does is fly out and look for the female to mate with. And then he dies immediately after mating. Actually, the teens asked me why was that, and I said because he's just done everything he needs to do. It was actually kind of hard to answer that. I wasn't quite sure. I said in a sense, that's kind of what all of us to, which the teens seemed a little sobered by. So, the story about drones is super interesting. So, what happens is that the drones are produced in the hive, of course, by—the queen lays all the eggs. The drones are produced there. The drones are raised by the workers, and then they just hang out until it's time for mating and for a new colony to be formed. At which point, the drones will leave and they'll form what are called drone swarms. And I've only seen this once in my life, and it was absolutely unforgettable. It was when I was in college, and my entomology professor took us to a place where he knew that drone swarms were likely to be common and a time of year when he knew it was likely to happen. And so when we were hiking up the trail you could hear this weird, ominous sounding buzzing in the air, but you couldn't see anything. And he bent down and picked up a little pebble and threw it up in the air. And it fell down and there were all these bees clustered all over it. And those were the drones that are attempting to jump onto a female—a virgin queen—as she leaves the hive and she flies through the swarm. And then as she does this, she flies faster and faster, and the drones are pursuing her. Eventually, one or more of the drones will end up able to mate with her. When they do this—and this is something that my students always really like. So, when they do this, they're genitalia explode as they produce the sperm. Yeah, everybody likes that. I don't know why everybody likes that. And then the rest of them falls to the ground and they die. And the queen flies back to the hive, often with the genitalia attached. And this is why—again, like the ancient Greeks and everybody was so flummoxed by how bees mate because there's this virgin queen coming back—or to start her colony, to start the swarm, and she's—something's been going on in there. But they have no idea where this happened. So, that's the deal with the drones. And, yeah, the exploding male genitalia is always a crowd pleaser. But the point being that a lot of times people just don't want to believe this because they have their own ideas in their mind about the way animals are. And, see, there's no place—oh, yeah. And so I kind of got a pet peeve about this, in case you haven't noticed yet. And so, seriously, the movie Ants was exactly the same way, and Every Ant Has His Day. It's her day. How hard would it be? People should really be getting this right. So, now all of you are going to get this right. Oh, thanks. Wow. Oh, all of you are going to get this right from now on. Okay, and I think that what this illustrates is a point that has fascinated me about insects forever, which is that insects do a great job of challenging our assumptions and breaking the rules that we think nature has. And there's no place where that's more true than when it comes to matters about sex. And people often say, oh, well, in nature females are coy and subservient and males are macho and dominant. It's kind of like they think the world is like a 1950s sitcom and that's just how it is. And the females take care of the young, and the males go out and—I don't know what they do. They go out and work at jobs somewhere. Well, that's what Jerry Seinfeld did in the Bee Movie. Anyway, in fact, that's just not the case. And my favorite example of why that's not the case is katydids. Katydids are relatives of crickets and grasshoppers, and the males in katydids—when they are going to mate—they produce—along with the sperm to fertilize the female's eggs—these big, globby things that are manufactured out of the male's own body. And they can weigh up to 30 percent of the male's body weight. And the female eats these either before or after mating, and—I just realized do I have a—yeah, you probably can't see it. So, the white thing here has the sperm in it. The green thing here is the nutritive thing that the male's manufactured. And so I always want to pause for just a second and—30 percent of your body weight. So, what that means is that if people needed to do this, then every time a man had sex he would have to manufacture—out of his own body—something that weighed 50, 60, 70 pounds every time. Okay, thinking about this, people often have a stronger reaction than you guys did. I guess this is okay for you. I mean, maybe that just sounds good to you. Okay, that would be fine, too. But the deal is that if you had to do that, you would not be able to do it very often. I mean, really, 50, 60, 70 pounds? You just couldn't. And that's also true for the katydids. And it turns out—but the females, they're totally great with getting lots of these things to eat because they help them produce more eggs, which is obviously good for them. So, what that means is that with katydids, the females are aggressive. They're very—they'll elbow other females out of the way in trying to get access to a male. They want to mate as much as they can. The males are very choosey. They only like really fat females because those are the ones who are going to have a lot of eggs and going to be able to have more of their eggs fertilized by them. And the point is—again, sometimes people will say, well, should we do—no. I'm not suggesting that people do this. The point is that when you look at insects, they seem like they just don't do the things that we think organisms are doing naturally. And so I sometimes feel like insects present both a window into the way life can be, and sometimes a mirror into the way life actually isn't, but we sometimes see ourselves reflected as. And one of the things that I really like about studying them is that you get this glimpse into what animals are like in a world where the rules are completely different. And I think it makes us really challenge a lot of what we think is normal or natural in our own species. And so what I'm going to do right now—and so I think that's really the moral of the story, if there is one, is that it's not that there's a particular way for males to be and a particular way for females to be. It's that insects are showing us that there's another way you can do things; a way that's just as natural and normal as the way that we do them. And my only final words are that insects—they do mirror us, but then they really don't. Thanks. [End of audio]