Beautiful botflies, luscious leeches, and the wonder of parasites

Sure, botflies are gross, but they also know just how to hitch a ride on a camel sneeze. An entomologist celebrates the world of parasites.

Speaker names marked ? are inferred from speaking time and the show’s known hosts — they are not voice-verified.

• 0:03Flora Lichtman?

  Hey, it's Flora and you're listening to Science Friday. Dr. Dino Martins has plucked maggots out of a dead elephant, pulled botflies out of camel snot, and let a horsefly feast on him consentingly. Why? Because he's obsessed with parasites. Dino is an entomologist who grew up in rural Kenya. He's worked all over the world to try to understand how insects keep this planet alive. And along the way, he met some of the world's most iconic freeloaders. Dino describes his journey into science and his love of parasites in his new book, Hidden Creatures: Luscious Leeches, Bashful Botflies,

• 0:45Flora Lichtman?

  and the wondrous, history-shaping world of parasites. Dino, welcome to Science Friday.

• 0:50Speaker 01

  Thank you so much, Flora. Delighted to be here.

• 0:53Flora Lichtman?

  I am delighted to have you. And I have to spend, right off the bat, a minute on those adjectives: luscious leeches, bashful botflies. I feel like you are doing the most to try to rebrand parasites. Why?

• 1:09Speaker 01

  Absolutely. So first of all, parasites are disgusting. I accept that. And they can be deadly as well. But they are also part of the fabric of life. And I think, for me, as a naturalist, as a scientist, if we're going to learn about things that are beautiful and interesting, we also have to learn about things that are disgusting and maybe even slightly disturbing.

• 1:35Flora Lichtman?

  I'm sold. I mean, what makes a parasite a parasite? Do you have, is it just you're a moocher?

• 1:42Speaker 01

  You know, that's a really fantastic question, because there isn't a single definition of parasites. And if we think about a parasite being something that feeds on other things, but in what units is one of the things that biologists debate. And I remember E.O. Wilson saying that he really liked precise definitions. And his definition was centered on the idea of a parasite being anything that fed on its prey in units of less than one.

• 2:18Flora Lichtman?

  What does that mean, a unit of less than one?

• 2:21Speaker 01

  So if you were a cow grazing on grass, you wouldn't be a parasite, even though you're feeding on something else. But if you're a tick feeding on the cow, you are a parasite because you're feeding in units of less than one. So it's, you know, like so many of these definitions in science, the closer you look, the more complicated it becomes. And it's very easy for us to define a parasitic relationship where, you know, a parasite is taking deriving benefits, nutrients, whatever else it's grabbing, it's mooching off others. And the host who is being targeted is paying a cost.

• 3:06Speaker 01

  So parasitic relationships are very easy to kind of quantify in a mathematical sense or in this kind of scientific sense. But when you actually look at nature, there's a lot of gray areas.

• 3:20Flora Lichtman?

  Are hosts always paying a cost? I mean, I'm thinking of like our evolving understanding of the microbiome and how we have, you know, bugs deriving nutrients from us, but also doing a service. Do you think that there's a world in which we just don't understand parasites well enough yet to understand the relationship?

• 3:41Speaker 01

  Absolutely. Just like the microbiome, our perception of parasites is starting to shift. Now, there's no question, there are many parasites that cause a tremendous amount of suffering and have a huge impact. But the question is, we have, as you said, evolved and co-evolved with parasites, as have many other creatures in the world. And so could there be a benefit in one way or another to actually encountering parasites? And the evidence is starting to gather, and the answer is yes. So just like the microbiome with all its complexity, exposure to parasites, perhaps when you're younger, for example, to certain parasites, helps build and train your immune system

• 4:26Speaker 01

  to deal with more dangerous or deadly things it might encounter later on in life. Parasites have all kinds of molecules and chemistry and weird genetics and extremely disturbing sex lives. And all of these

• 4:43Flora Lichtman?

  Do you want to give us an example, as long as we're here?

• 4:47Speaker 01

  As long as we're here, yes. So I describe how mosquitoes actually mate. In the book, I'm with my students and we see them mating and they mate in the missionary position, which is extremely entertaining for the students and not sort of what we would expect of mosquitoes. You know, you'd think they'd be a little bit more kind of, you know, sort of, who knows? I'm struggling to find the right word here, but.

• 5:13Flora Lichtman?

  It's hard to know what it would be like. I have to say, it's not something I've thought about before.

• 5:19Speaker 01

  But, you know, ticks are another amazing one and some species mate on the host, like on the dog. And, and the male actually has to do like all this foreplay to get the female really sort of in the mood and, and excited. And then this, you know, this might be too much for readers, listeners of a sensitive nature, but he actually uses his mouth parts to do it. And, um, yes, I'll just leave it at that.

• 5:52Flora Lichtman?

  You got a warning, listeners. Let's, let's talk about your path to parasites. I want to go back to when you were a kid and I don't think I've ever uttered this sentence, but growing up, you had a pet baby zebra. How did he come into your life?

• 6:10Speaker 01

  Yes, I did. You know, so I, I was very lucky to live in a, in different parts of Kenya growing up and lived for part of the time on the plain south of Nairobi at a place called Kitangela and surrounded by all kinds of different animals. And, well, BZ, as we called him, which stands for baby zebra, he, yes, we weren't very imaginative with some of the names. We, we also had Craney and who was a crane and Mary Boo, who was a marabu stork. So.

• 6:46Speaker 01

  So BZ kind of fitted with the rest of the family. What happened? There was a drought and during drought, you know, many baby animals, other animals get kind of abandoned or there's other kind of disruptions. And that's how BZ was found because he'd been in the drought. He'd been abandoned. He was, he was very thin and kind of full of parasites and starving. So he was found one day and he was brought to me and I had to learn how to take care of him.

• 7:12Flora Lichtman?

  So BZ had this eye parasite and I want to talk about your response to that. So you saw this worm, worms coming out of his eyes. And yeah, I think many people would be like, oh, that's gross. You were like, I have to know more. And not only pulled them out and looked at them under the microscope you had access to. You went, it sounds like to a vet's office to look at it under an even stronger microscope. And I wondered, is this sort of who you've always been, just sort of determined to follow your curiosity?

• 7:54Speaker 01

  Absolutely. And I've been very lucky to have teachers and vets and lots of other people who've supported me and encouraged me in being curious. But even when I haven't had a lot of encouragement, I'm very curious and I can be quite, in a very, I think a gentle way, be quite pushy. And I remember in school showing up with various parasites. And some of the teachers were horrified, but at least they didn't discourage me. They were like, okay, we can learn about this.

• 8:25Flora Lichtman?

  Does your scientific interest in, you know, in insects? And now also the side quest into parasites relate to where you grew up and where you've decided to live and work?

• 8:39Speaker 01

  Absolutely. And I think one of the things about insects, you know, everyone was like, you grew up in Kenya. Why didn't you study lions or rhinos or elephants or go off and study even, you know, other big animals? But growing up, I was often quite alone and.

• 8:56Speaker 01

  I had to kind of entertain myself. And the thing is insects are easy to find. I could find them and I could catch them and I could observe them really closely, which is something I've I've always wanted to do is to really see things and see all the details. And so insects became my companions, they became my friends, they I I would turn them into characters in, you know, in my imagination, I would draw them. Uh, and and as a result, I I started learning that by seeing these details, you start to understand what's happening beneath the surface, be beneath what is really obvious. Uh, you know, and that that was like, wow, you know, just so mind mind blowing.

• 9:41Speaker 01

  And um, in the book, I talk about, you know, uh, raising caterpillars and watching one, uh, you know, sort of parasites erupt from its body, which is absolutely horrifying to watch, especially when you've cared for this caterpillar and you've been feeding it every day and you know, you feel like it's it's it's your it's you really care about it, but then it's being like eaten alive, which is horrifying. And then you actually watch what happens next, which is these wasps emerging. And then you realize in some insects, uh, actually there are there are parasites of parasites. And it's just like, at first, you almost like I might get a headache from thinking about all of this because it's so complicated, but then it's actually so wonderful as well.

• 10:28Flora Lichtman?

  I have to take a quick break, but when we come back, do we need all parasites, really? Stay with us.

• 10:40Speaker 02

  Support for Science Friday comes from Science Sandbox, an initiative of the Simons Foundation.

• 10:52Flora Lichtman?

  We've been reading about parasites a lot right now. Screw worms, cyclosporiosis, giving people stomach distress in the US right now.

• 10:59Speaker 01

  Yes, yeah.

• 11:00Flora Lichtman?

  Of course, malaria, ticks, carrying diseases. Are there some that you think we could wipe out?

• 11:07Speaker 01

  Okay, so that's an interesting question. It's a moral question as well as a biological one. And the answer is, you know, in some ways, yes. We already have eradicated certain pathogens that have caused diseases through history. Smallpox, for example, rinderpest, which was a viral disease that used to kill animals here. And it was transformative for the ecology and the empire and the political outcomes for many countries in terms of these changes. But I would make the case that the answer is no. We do not have the right to eradicate any other species, even though, of course, we

• 11:52Speaker 01

  do it all the time. But the challenge with parasites is this, is that we need to approach it with a little humility. Parasites are not as simple as viruses. They are actually complex organisms that can think and can behave and can adapt and can respond. They can exploit opportunities that we create for them, whether it's through the increased concentration of animals in feedlots, or it's through fish farming, or it's through transporting animals across the planet. We're changing the rules of the game all the time. But parasites are the one group of animals who are one step ahead of us. They're like, okay, you changed the rules.

• 12:36Speaker 01

  We're going to cheat and we're going to do this and we're going to exploit this opportunity. And I think... We might think we can eradicate them or we can get rid of them. But I don't think we ever will because they are benefiting from what we're doing. And so the, I think the better way to approach it is to say, look, here they are. They are part of this incredible fabric of life, this living system that supports us and all the, you know, people and animals we care about. How, how do we understand it better? How do we engage with it?

• 13:16Speaker 01

  And, and we do need to solve some very serious problems of parasite, uh, you know, diseases, for example. And the only way we will do that is actually by, you know, better science, science that's much more collaborative, that's much more global. Because for parasites, there are only bodies, there are no borders. And the fact is, no matter where you are, who you are, how privileged you think you might be, how safe you might be, you think, wherever you're living in a city or somewhere removed from nature. You know what? You will never escape from a parasite. They are coming to get you. And so you better learn about them.

• 14:00Flora Lichtman?

  You know, listening to you talk, it feels like you have a, you do a good job of holding both the sort of

• 14:08Flora Lichtman?

  frightening elements of parasites, the, the wonder of them, the disgusting elements all at once. How do you, how do you do that? What's your secret?

• 14:17Speaker 01

  Um, thank you. I, I don't know if I do, but basically my, my secret is, I think, twofold. One is just to be curious, just to be open minded and to go out there and kind of be open to the unexpected. The other part of it is actually, you know, I'm very lucky to have animals as teachers as well. And so understanding that on every body, on every branch, on every single person, there is another organism. And we might not sometimes want to think about it. It's like quite horrifying and disgusting, but if we don't, if we don't, we might miss out on some really cool stuff that's happening. Just like you'd never know what you're going to find out there. And the remarkable thing is,

• 15:03Speaker 01

  Imagine the most horrific, bizarre sci fi scene you've ever, ever seen in a movie.

• 15:13Speaker 01

  And I can assure you that in nature, you will find something even more horrifying and wonderful all at once.

• 15:23Flora Lichtman?

  Okay, well, leave us with one great example, the cinematic parasite that you want us to all know and if not love, revere.

• 15:32Speaker 01

  Oh, wow. Gosh, that's a really great question. Um, there's so many sort of racing through my mind. Let me, let me try.

• 15:41Speaker 01

  Let me try and think through this one.

• 15:45Speaker 01

  If I were to think about one of the parasites that I often find with students that completely horrifies them, is the botfly. And it, botflies are, you know, these complex parasites, they're flies, they're actual flying around as adult flies, you know, doing all kinds of fly-like behaviors and have to find each other and mate and, and, and, and then they have to lay their eggs. And the eggs develop in some cases in the nostrils or in the throat or in the stomach.

• 16:22Flora Lichtman?

  Whose nostrils?

• 16:24Speaker 01

  Um, well, mostly it happens to other animals, but it has occasionally happened to people. But the botfly is like actively making these decisions, you know, it has to navigate all this complexity. It has to get its eggs into the nostrils or the lips or the mouth of another animal. In the case of the rhinoceros or the horse botfly, they, or the elephant one, in fact, they have to be swallowed. And, and you just, isn't that wonderful and amazing to think about? That, that this entire thing could be living inside you and thinking and making like all these decisions.

• 17:03Speaker 01

  And then, of course, it has to face this ultimate challenge. It has to get out of you, back into the world. And, you know, that's like a really fraught moment.

• 17:14Flora Lichtman?

  Why is it a fraught moment?

• 17:16Speaker 01

  Because if you think about it, so for example, when they go into the nostrils of camels or deer, or maybe even people occasionally, that doesn't happen very often, let me not terrify too many listeners.

• 17:30Speaker 01

  They have to get out. So what they do is they like tickle the inside of the nose. And so the animal sneezes. And now they've got to, they shoot out like a rocket, you know, flying across. And they've got to land in the right place because if they land on, on like, you know, the wrong place, they could, that could be it, that could be the end of their life. And they've invested so much in getting to this point. So, so you know, they, there's all like these risks they've got to overcome and all these cap probabilities that, that are sort of stacked against them. And yet somehow they make it, you know, somehow they make it and they're out there in the world just being fabulous, which is, which is wonderful.

• 18:11Flora Lichtman?

  Do you know, I want to see the world through your eyes. I feel like it's a, they would help with my brain chemistry.

• 18:19Speaker 01

  I, I believe that we all have the ability to see the details of nature. But I really don't think it's, it's me. I'm, I'm not very special. I'm just, you know, holding on to that childlike wonder that everybody has. But I also know that we as humans have this incredible ability to see detail and to engage with it. And we have all these senses that we can experience the world with. And so for me to really, for us to really understand and see the whole picture of life and nature and evolution, we have to sort of see everything, hear everything, taste everything, feel everything, squirm alongside everything.

• 19:03Speaker 01

  And, and yes, the disgusting parts of it. And then in that disgusting moment, we'll realize, actually, you know, this is a bit divine as well.

• 19:15Flora Lichtman?

  I love this call to action, Dino. Thank you. I really do.

• 19:19Speaker 01

  Thank you.

• 19:21Flora Lichtman?

  Dr. Dino Martins is an entomologist and author of Hidden Creatures. He's based in Malindi, Kenya. Dino, thanks again for joining me today.

• 19:29Speaker 01

  Thank you so much. Take care.

• 19:31Flora Lichtman?

  To sink your teeth into more parasite stories, head to sciencefriday.com/parasites to read an excerpt from Dino's book. This episode was produced by Rasha Aridi. Thank you for listening and we'll catch you next time. I'm Flora Lichtman.