Beautiful botflies, luscious leeches, and the wonder of parasites

[MUSIC PLAYING] FLORA 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 horse fly 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, and the Wondrous, History Shaping World of Parasites. Dino, welcome to Science Friday.

DINO MARTINS: Thank you so much, Flora. Delighted to be here.

FLORA 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?

DINO MARTINS: 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 sort of disturbing. [LAUGHS]

FLORA LICHTMAN: I’m sold. I mean, what makes a parasite a parasite? Is it just you’re a moocher?

DINO MARTINS: 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 kind of debate. And I remember EO 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.

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

DINO MARTINS: 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 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 a parasite is deriving benefits, nutrients, whatever else it’s grabbing, it’s mooching off others, and the host who is being targeted is paying a cost. So parasitic relationships are very easy to 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.

FLORA LICHTMAN: Are hosts always paying a cost? I mean, I’m thinking of our evolving understanding of the microbiome and how we have 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?

DINO MARTINS: 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 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 aspects–

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FLORA LICHTMAN: Do you want to give us an example, as long as we’re here?

DINO MARTINS: [LAUGHS] 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 what we would expect of mosquitoes. You’d think they’d be a little bit more– who knows? I’m struggling to find the right word here.

FLORA LICHTMAN: It’s hard to what it would be like. I have to say it’s not something I’ve thought about before.

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

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FLORA LICHTMAN: You got a warning, listeners. 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?

DINO MARTINS: Yes, I did. So I was very lucky to live in different parts of Kenya growing up and lived for part of the time on the plain south of Nairobi at a place called Kitengela and surrounded by all kinds of different animals. And well, BZ, as we called him, which stands for Baby Zebra– yes, we weren’t very imaginative with some of the names. We also had Craney, who was a crane, and Mary-Boo, who was a marabou stork.

So BZ fitted with the rest of the family. What happened, there was a drought, and during drought, many baby animals, other animals get 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 very thin and 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.

FLORA LICHTMAN: So BZ had this eye parasite. And I want to talk about your response to that. So you saw the 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 more, and not only pulled them out and looked at them under the microscope you had access. You went, it sounds like, to a vet’s office to look at it under an even stronger microscope. And I wondered, is this who you’ve always been, just determined to follow your curiosity?

DINO MARTINS: 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, OK, we can learn about this.

FLORA LICHTMAN: Does your scientific interest in insects and now also this side quest into parasites relate to where you grew up and where you’ve decided to live and work?

DINO MARTINS: Absolutely. And I think one of the things about insects– everyone was like, you grew up in Kenya. Why didn’t you study lions or rhinos or elephants or go off and study even other big animals? But growing up, I was often quite alone, and I had to 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 always wanted to do, is to really see things and see all the details. And so insects became my companions. They became my friends. I would turn them into characters in my imagination. I would draw them.

And as a result, I started learning that by seeing these details, you start to understand what’s happening beneath the surface, beneath what is really obvious. And that was like, wow, just so mind blowing. And in the book, I talk about raising caterpillars and watching 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 really care about it.

But then it’s being 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, actually, there are parasites of parasites. And it’s just like, at first, you’re 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.

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

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FLORA LICHTMAN: We’ve been reading about parasites a lot right now– screwworms, cyclosporiasis giving people stomach distress in the US right now, of course, malaria, ticks carrying diseases. Are there some that you think we could wipe out?

DINO MARTINS: OK, so that’s an interesting question. It’s a moral question as well as a biological one. And the answer is, 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 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. Just 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, OK, you changed the rules. We’re going to cheat, and we’re going to do is, 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 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 people and animals we care about. How do we understand it better? How do we engage with it? And we do need to solve some very serious problems of parasite diseases, for example. And the only way we will do that is actually by 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. [LAUGHS]

FLORA LICHTMAN: Listening to you talk, it feels like you do a good job of holding both the frightening elements of parasites, the wonder of them, the disgusting elements all at once. How do you do that? What’s your secret?

DINO MARTINS: Thank you. I don’t know if I do. But basically, my secret is, I think, twofold. One is just to be curious, just be open minded and to go out there and be open to the unexpected. The other part of it is, actually, 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 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 never what you’re going to find out there. And the remarkable thing is, imagine the most horrific, bizarre sci-fi scene you’ve ever seen in a movie. And I can assure you that in nature, you will find something even more horrifying and wonderful all at once. [LAUGHS]

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

DINO MARTINS: Oh, wow. Gosh, that’s a really great question. There’s so many racing through my mind. [LAUGHS] Let me try and think through this one. If I were to think about one of the parasites that I often find with students that completely horrifies them is the botfly. And botflies are these complex parasites. They are flies. They’re actual flying around as adult flies, doing all kinds of fly-like behaviors, and have to find each other and mate. 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.

FLORA LICHTMAN: Whose nostrils?

DINO MARTINS: Well, mostly, it happens to other animals, but it has occasionally happened to people. But the botfly is actively making these decisions. 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 or the elephant one, in fact, they have to be swallowed.

And isn’t that wonderful and amazing to think about, that this entire thing could be living inside you and thinking and making all these decisions? And then, of course, it has to face this ultimate challenge. It has to get out of you back into the world. And that’s a really fraught moment.

FLORA LICHTMAN: Why is it a fraught moment?

DINO MARTINS: 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. They have to get out. So what they do is they tickle the inside of the nose. And so the animal sneezes, and they shoot out like a rocket, flying across, and they’ve got to land in the right place.

Because if they land on the wrong place, that could be it. That could be end of their life, and they’ve invested so much in getting to this point. So there’s all these risks they’ve got to overcome and all these probabilities that are stacked against them. And yet somehow they make it. Somehow they make it, and they’re out there in the world just being fabulous, which is wonderful. [LAUGHS]

FLORA LICHTMAN: Dino, I want to see the world through your eyes. I feel like it would help with my brain chemistry.

DINO MARTINS: I believe that we all have the ability to see the details of nature. But I really don’t think it’s me. I’m not very special. I’m just 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 us to really understand and see the whole picture of life and nature and evolution, we have to see everything, hear everything, taste everything, feel everything, squirm alongside everything, and yes, the disgusting parts of it. And then in that disgusting moment, we’ll realize, actually, this is a bit divine as well.

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

DINO MARTINS: Thank you.

FLORA 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.

DINO MARTINS: Thank you so much. Take care.

FLORA LICHTMAN: To sink your teeth into more parasite stories, head to sciencefriday.com 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.

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