[RADIOLAB INTRO]

JAD ABUMRAD: Hey, I'm Jad Abumrad.

ROBERT KRULWICH: I'm Robert Krulwich.

JAD: This is Radiolab.

ROBERT: The podcast.

JAD: What are we going to do today, Robert?

ROBERT: I think we're going to get rid of something.

JAD: And, here to tell us what and why, is producer Andy Mills.

ANDY MILLS: Okay. So a while back, I was talking with author Sonia Shah.

SONIA SHAH: I've had a very fraught relationship with mosquitoes for a long time.

ANDY: She actually wrote a book about malaria and mosquitoes ...

SONIA SHAH: Called The Fever.

ANDY: And for her, it all really started when she was a kid.

SONIA SHAH: Well, I grew up visiting India every summer because my family is from there, all my cousins, all my my grandparents, they were all there.

ANDY: Summer vacations.

SONIA SHAH: Summer vacations in India with my cousins. All I wanted to do is fit in.

ANDY: But the mosquitoes would always call her out.

SONIA SHAH: They knew!

ROBERT: There was a Yankee in the group.

SONIA SHAH: They would just focus on me. And so they wouldn't bite my cousins, they would be totally unscathed and I would be, like, covered in welts. I ended up having to sleep under a mosquito net, which is even more kind of isolating under this, like, suffocating net.

ANDY: She says at night when mosquitoes would land on her net, she would think ...

SONIA SHAH: I hate you. I hate you. But at the same time, I'm not allowed to do anything to them.

ANDY: And here's when you get to the fraught part, because Sonia and her family belong to this religion, called Jain Dharma.

SONIA SHAH: It's kind of an extreme nonviolent philosophy. You're not supposed to—you're not supposed to eat meat, obviously. You're not even supposed to eat any root vegetables because then you're killing the whole plant. You're not supposed to walk on grass because if you walk on grass, you can kill little insects. When you pray, you're supposed to wear a mask so you don't breathe in any, like, microbes or insects and inadvertently kill them. So I had to act like I'm totally cool with the mosquitoes around me.

ANDY: But every so often, Sonia says ...

SONIA SHAH: I would see a mosquito land near me, and when I thought no one was looking, I would just sort of mush it with my hand. And I still can feel, like, that tingly feeling on my hand just telling you that story. That tiny body being crushed by my hand. I mean, it just—it makes me feel terrible.

ANDY: And Sonia's ambivalence toward the mosquito, it has stayed with her her entire life, pretty much. Because on the one hand, she knows the mosquitoes have gotten a bad rap.

SONIA SHAH: First of all ...

ANDY: ... they don't really want to suck your blood.

SONIA SHAH: They don't want to risk their lives to get a blood meal. It's the most dangerous thing they're ever gonna do because it's so easy for us to kill them. On top of that, when they fill up with your blood, that blood is several times heavier than their own body weight. So suddenly, they're full of this stuff and they can't fly very well anymore.

ANDY: And on top of that, the only mosquitoes that bite you are the ladies.

SONIA SHAH: And the only reason they do it is because of all the protein in blood, and they use that to nourish their eggs.

ANDY: If they didn't have the protein in that blood, nearly all their babies would die.

SONIA SHAH: So they're really only do—they're not even doing it for food, you know?

ROBERT: So every bite is just good mommying, really.

SONIA SHAH: You could say that.

ROBERT: We have to just put out the message that when you're being swarmed by mosquitoes biting you, that you're just being swarmed by good ladies who are just nurturing.

SONIA SHAH: [laughs]

ROBERT: That might change the attitude.

ANDY: I do not fail to appreciate the charm of the mommy mosquito.

ROBERT: Good.

ANDY: But on the other hand, think of all the misery they have caused human beings.

SONIA SHAH: There's good estimates that get bandied around that one half of all human deaths since the Stone Age have been due to malaria.

JAD: Whoa!

ROBERT: One half!

SONIA SHAH: One half of all human deaths since the Stone Age. So it's had a huge, huge impact on our species. We know this.

ANDY: And for me, this is not just some, like, far away, sad statistical abstraction, right? Like, you know I used to live and work in Sudan. And while I was there, I saw the children's wards at the clinics and hospitals. Like, I saw the kids dying of this disease, all from a mosquito. And kind of where I'm headed with this is that, like, I mean, could this be the creature that we can all agree that we should just get rid of?

ROBERT: You can hope for that, Andy, but it's not gonna happen because mosquitoes are incredibly fertile. They—you could make a little groove on a rainy day in the mud, and they will have babies in that little patch of water.

JAD: It's like a baby party.

ROBERT: They're like a baby party.

JAD: In a footstep.

ROBERT: Exactly. So there is no ...

JAD: Yeah, you can't wipe that out.

SONIA SHAH: Well remember, mosquitoes, you know, they reproduce really fast. A typical mosquito only lives for, like, a week or so. So many, many, many generations are evolving as we're throwing chemicals at them. And as soon as one evolves some way to withstand it a little bit better, that little creature sort of sweeps its genes throughout the population. And that can happen within, like, a few years. Like, so three, five, seven years is kind of the time horizon for when you start using a chemical against the mosquito to when the mosquito population becomes resistant to it.

ANDY: Wow!

SONIA SHAH: It's a problem.

ANDY: But—but what if I told you that we had gotten to the point where we could solve this problem?

ROBERT: Oh, you'll have to show me an example.

ANDY: Oh, that would make me so happy to show you. I sent reporter David Baker down to this small town in eastern Brazil, to check out this factory.

DAVID BAKER: Here is a mosquito factory. Just as we come in, a woman with a kind of electric tennis racket is killing an insect on the wall.

JAD: A mosquito factory?

HADYN PERRY: Yeah, it sounds strange, but the world's largest mosquito factory is in Brazil.

ANDY: This is Hadyn Perry.

HADYN PERRY: Chief executive officer of Oxitec.

ANDY: And by factory, he means that this is a place where people actually breed mosquitoes, a very special kind.

HADYN PERRY: I think at the moment, they're making about four million or so a week.

DAVID BAKER: Oh, dear!

ANDY: After you pass through a couple of airlocks, you enter this massive room.

DAVID BAKER: It's a huge concrete warehouse.

ANDY: Where there are rows and rows of buckets. How this works is that Hadyn and his company in England, they will send the factory workers here a batch of eggs.

ALDO MALAVASI: And then we'll remove the eggs and put it in the water. I am Aldo Malavasi, director of the Medfly and Mosquito Facility in Brazil.

HADYN PERRY: And inside ...

ANDY: ... each of these buckets.

DAVID BAKER: What's that, a gram?

ALDO MALAVASI: How many?

DAVID BAKER: Inside is 80,000 eggs. And they look like they're just tiny, tiny little black dots.

ALDO MALAVASI: After we put the eggs, in about half hour to one hour they start to hatch, and then we have a small larvae.

DAVID BAKER: Now you can see lots of—this is larvae. These are larvae. Lots of mosquito larvae swimming in the water. Whoa.

ANDY: They look like long translucent worms with spikes all over their bodies.

DAVID BAKER: If someone said, "Put your hand in there," I'm not sure if I would.

WORKER: It's beautiful.

DAVID BAKER: [laughs]

ANDY: Now according to Hadyn, when these mosquitoes grow up and become adults, they will look ...

HADYN PERRY: ... completely indistinguishable from normal mosquitoes, except—except that they carry this lethal gene.

ANDY: Hadyn's company has actually put a tiny little extra special, extra deadly gene inside their bodies. Which ...

HADYN PERRY: So here ...

ANDY: ... you can actually see. At a certain point in David's trip, one of the factory workers, they brought over this special UV light and they shined it over the larvae.

DAVID BAKER: Oh, goodness me! It's like something from Alien. It's like wiggling larvae that is full of these kind of globules that are glowing red, like, from inside its body. Those are the genes that are glowing?

ALDO MALAVASI: Yes.

DAVID BAKER: Wow!

ANDY: Hadyn and his company, they have genetically engineered this glowing red gene, so that when it turns on ...

HADYN PERRY: It actually produces a certain protein.

ANDY: Inside of these mosquitoes, the gene starts cranking out these proteins more and more and more and more, until the cell basically goes ...

HADYN PERRY: Out of control, and the insect dies.

ANDY: This is the evil genius part. They turn off this gene temporarily. Then in another room in the factory, they hatch the babies, grow the mosquitoes in these test tubes.

DAVID BAKER: A thousand, perhaps of these plastic tubes. Inside are mosquitoes, loads of them.

ANDY: Then they separate ...

WORKER: Pupae females and males.

DAVID BAKER: Females and males, okay.

ANDY: Then they take just the males ...

HADYN PERRY: Put the males into little pots.

ANDY: They take the pots out into cities and towns. And every few hundred feet ...

HADYN PERRY: They shake these pots out.

ANDY: And release the mosquitoes into the wild.

HADYN PERRY: Those males, they go out there, they are just tuned in to finding females.

ANDY: Remember, those are the ones that bite.

HADYN PERRY: They tune in to the wing beat, and off they go, find a female. They're satisfying their biological urge to mate.

ANDY: Then the female will go off and lay her eggs. The eggs will hatch, and then inside each and every one of those little babies, the gene will turn on, they'll start pumping out those proteins, the cell goes out of control ...

HADYN PERRY: And larvae will die before they become functioning adults. So instead of that female laying a hundred eggs at a time or up to 500 in their lifetime, she lays the same number, but they die. To give an example of the last trial, they were working in a town called Mandacaru. About 3,000 people there.

ANDY: Mandacaru is this small town in Brazil that's had a really terrible time with the disease that the mosquitoes spread there called dengue fever, which can make you ...

HADYN PERRY: ... feel as if your bones are breaking.

ANDY: And it can sometimes cause ...

HADYN PERRY: ... bleeding from the eyes or ears.

ANDY: And in kids, death. In the past decade, what you've seen is cases of dengue going up and up and up.

HADYN PERRY: Yeah.

ANDY: But in 2011 ...

HADYN PERRY: ... they started releasing our males.

ANDY: All across town, they release these mutant males. And then they waited.

HADYN PERRY: And within about six months, they reduced the population of the mosquitoes by 96 percent.

JAD: Wow! 96 percent!

HADYN PERRY: Yeah. In that town. So in six months, you've pretty much eliminated the mosquito population.

ANDY: And this wasn't just some one off thing because the next year, after the rainy season ...

HADYN PERRY: ... instead of seeing that massive explosion of mosquito numbers, which you get every single year, you didn't see any increase at all.

ANDY: Wow!

HADYN PERRY: Because there wasn't a population there to build up.

ANDY: And this? This is just the beginning.

HADYN PERRY: In Brazil, there's been a series of trials ...

ANDY: ... in a bunch of different places.

HADYN PERRY: ... and they're all over 90 percent.

ANDY: As in 90 percent of the population was killed in the first round. And they've released them in different parts of the Cayman Islands.

HADYN PERRY: And again, that was the same idea. We had over 90 percent reduction.

ANDY: They're starting their first trials in Panama. They're in talks with local government officials in India, Malaysia, and the USA.

SONIA SHAH: Yeah.

ANDY: Can we just think about what would the world look like without mosquitoes?

SONIA SHAH: I mean, California, there's hardly any mosquitoes there. It would be like California everywhere. That would be totally awesome.

ROBERT: Both of you are acting like the only thing that happens with these animals is they make humans—and particularly human children—sick.

SONIA SHAH: It's not them, it's the parasite.

ROBERT: Right.

ANDY: But they're the ones—they're the ones who are spreading it. And so if our idea is you stop the mosquito, you stop the malaria, then I ...

ROBERT: It might stop a few other things, that's all I'm saying. Just call David.

ANDY: So we did. That's a really good mosquito impression, actually.

JAD: Is that David?

ROBERT: That's David.

ANDY: That's David.

ANDY: We called David.

DAVID QUAMMEN: I'm David Quammen. I'm a science writer based in Bozeman, Montana.

ANDY: The reason that Robert wanted us to call him this time is because a long, long time ago ...

DAVID QUAMMEN: Many, many, many years ago ...

ANDY: ... David wrote an article for Outside Magazine ...

DAVID QUAMMEN: ... titled "Sympathy for the Devil ..."

ANDY: ... that wrestled with the following question:

DAVID QUAMMEN: What, if anything, are the redeeming merits of the mosquito? These critters have a lot to answer for, but is that the whole story? Should we therefore dismiss them?

ANDY: Or destroy them?

DAVID QUAMMEN: Or destroy them, eradicate them?

JAD: Did you come up with things to say about this?

DAVID QUAMMEN: Well, wasn't easy, but I did, yeah. I read, read and ...

ANDY: And while he read, he said he did turn up some interesting facts. For example, there is this mosquito that lives up in the Arctic ...

DAVID QUAMMEN: Aedes nigripes.

ANDY: ... which ...

DAVID QUAMMEN: ... pollinates Arctic orchids and spreads no disease to anybody.

ANDY: Which is nice, but then David made the following argument:

DAVID QUAMMEN: Because of their pestiferous disease vectoring ...

ROBERT: Pestiferous disease vectoring, whoa!

DAVID QUAMMEN: ... they have made tropical forests very, very difficult for humans to inhabit, to colonize over the last 10,000 years.

ANDY: Because every time that we would try and go into those forests, we would get swarmed by mosquitoes and we'd run away.

DAVID QUAMMEN: And therefore, they have played an important role in bringing those forests forward relatively intact into the 20th and 21st centuries. If there were no difficulties, diseases, threats to the people living in those forests, then those forests would have been turned into settlements, cities, farmlands, much more extensively and much earlier than they have been and are now being. I call them nature's Viet Cong because they are ...

JAD: [laughs]

DAVID QUAMMEN: ... they are the resistance fighters on behalf of the rainforest.

ROBERT: Well, why don't we make it harder for you? Why don't we make you imagine that it's springtime or early summer in Alaska, that there's tundra melting everywhere, that there are hordes and hordes and clouds of mosquitoes, and they're forming a permanent sort of cloud around you. And then Andy Mills comes up and offers you the opportunity to eliminate them completely from the planet. And he makes this offer as they are stabbing you in the wrist, face, cheek and ear, you would do what?

DAVID QUAMMEN: I would do these two things: first, I would unzip the mosquito net of the tent and I would say, "Andy, for God's sake, let's have this conversation in the tent." And we would jump in the tent, zip that thing. Now I'd say, "Okay, now Andy, we can think about this clearly." And one of the things I'd say was, "Well, look, if we're up here, just two humans in the middle of this Alaskan tundra, and there are these millions and millions of mosquitoes swarming around us to get our blood, obviously, we're a small factor on this landscape, and they're a big factor in some way. So if we were to press a button and eradicate them instantly, it's very difficult to know their load-bearing significance in the ecosystem because they're playing lots of different roles as parasites, as competitors, as prey.

ANDY: But one of the things that Sonia Shah told me is that they actually don't play a big role in the ecosystem.

SONIA SHAH: I mean, I really tried hard when I was writing this book to get a mosquito biologist to explain to me that mosquitoes were useful, that they had some sort of ecological role to play that was important. And no one would admit that they had any role at all. They'd say they're not a useful nutrition for bats or fish or any of the other, like, predators of mosquitoes because their biomass is so small that, you know, those creatures would be fine without mosquitoes. Like, everyone would be fine without mosquitoes.

DAVID QUAMMEN: She might be right about that, but that's not the only ecological dimension we're talking about. That does not prove ...

JAD: What other dimension might there be, just as a "for example?"

DAVID QUAMMEN: Competition. They might be competing with other insects. Then if you eliminate the mosquitoes, then suddenly filaria flies become much more abundant.

ANDY: Oh!

DAVID QUAMMEN: I mean, when you talk about trying to foresee the consequences of completely eradicating any one species, we just don't know.

ROBERT: The real deep thought here is if you're going to destroy, the only obligation you owe to yourself is to know what you're killing.

DAVID QUAMMEN: Absolutely. And by that, I mean, yes, to know absolutely the dimensions, the implications of what you're doing.

ANDY: And what I'm weighing on here, Quammen, is that, like, I too have been to some of these sub-Saharan parts of Africa, and I just was floored that we have a curable disease, and how many, like, 12-, 13-, 14-year-old kids were holed up in this ward, you know?

DAVID QUAMMEN: Well, I agree with you that that's urgently compelling and important, and I feel the same way that something needs to be done. And it's true to some extent ...

ANDY: In the end after all the debate, I've ended up at this kind of middle ground.

HADYN PERRY: Well, I think what we aim to do, actually ...

ANDY: Hadyn Perry put it to me like this: we don't have to kill them all everywhere—and in fact, maybe we shouldn't—but we can kill them where we live.

HADYN PERRY: Eliminate them in our major urban cities and towns, that they no longer pose a threat.

ANDY: We can draw a line and say, "You know what? You stay out in the woods, we'll stay here," because the diseases that they're spreading, they will go away if the mosquito goes away for long enough. Because if we get better—like, in America, we don't get malaria hardly ever because there's no one with malaria that a mosquito would bite and then give that malaria to someone else.

ROBERT: Oh!

JAD: Ah!

ANDY: We have a ton of anopheles mosquitoes, and we have less than a thousand cases of malaria a year. Almost all those cases are somebody like myself who gets sick in Africa, comes back here. And why is that? Because we hit zero. Well, I mean, close to zero in our cities and towns. Once people stopped having malaria here, mosquitoes stopped getting it and giving it to other people.

SONIA SHAH: We just have to kind of place the boundary a little bit better. The mosquitoes can still do their thing, we can do our thing.

ANDY: So you don't hate them anymore is what you're saying.

SONIA SHAH: I think there's a way to live harmoniously with the mosquitoes. I mean, we do it in this country, right? I mean, we have mosquitoes, and we control their populations in many ways, but we also get bit.

ROBERT: Special thanks to Andy Mills, of course, who learned bug tolerance through Radiolab.

JAD: Also a very special thanks to David Baker who went above and beyond in the pursuit of mutant mosquitoes. And thanks also, big thanks, to writer, Sonia Shaw, and to you guys for listening. I'm Jad Abumrad.

ROBERT: I'm Robert Krulwich.

JAD: See you next time.

[LISTENERS: This is Eric. And Rebecca. And we're calling from St. Croix. In the U.S. Virgin Islands. Where we just sailed down from Savannah, Georgia In an 88 year old Grand Banks Dosser fishing schooner. Radiolab is supported in part by The National Science Foundation. And by the Alfred P. Sloan Foundation. Enhancing public understanding of science and technology in the modern world. For more information about Sloan at www.sloan.org.]

 

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