Return of the Flesh-Eaters

7:07Robert Krulwich:Could we actually, could you just tell me what a screwworm even is?

7:10Edward F. Knipling:It is a fly. It has kind of like.

7:13Robert Krulwich:Why do they call it a worm if it's a fly?

7:15Edward F. Knipling:Well, flies are also maggots, right? Like our flies come from maggots. So the maggot phase is a worm.

7:20Robert Krulwich:Okay, okay, okay.

7:21Edward F. Knipling:So basically what they do is that if you have a little like nick in your skin, a little wound.

7:26Robert Krulwich:Even something as small as a tick bite.

7:28Edward F. Knipling:These flies would lay their eggs in those wounds.

7:31Robert Krulwich:Roughly 400 eggs at a time. Oh my God.

7:34Edward F. Knipling:And then these maggots essentially would come out. They kind of look like a small white thread.

7:39Robert Krulwich:They have this kind of horrifying mouth with two sharp teeth and a little ridge on their body that sticks out exactly the way the threads on a screw do. They would twist themselves down.

7:50Edward F. Knipling:Kind of burrow themselves into the flesh like a screw, and they would eat the flesh. Oh, yeah, it's...

8:00Robert Krulwich:And they are extremely hard to get out once they have locked in. A screw worm would get into the navel of calves when they were born.

8:10Jad Abumrad:And so back to young Edward Nippling.

8:12Robert Krulwich:He got probably the worst job on the farm, which was to pick the screwworms out of the family's cows. And that was a very unpleasant task. Have to try to yank them out of these animals that obviously aren't happy about this. Is there a tool you used? I'm guessing a tweezers or just fingers. Screwdriver. You got to use a screwdriver. That was his job. And it introduced a lifelong hatred of screwworms in his heart. You know, understandably so.

8:41Jad Abumrad:But at the same time, you know, he has sort of a scientific bent of mind. He's curious.

8:45Robert Krulwich:He was actually kind of fascinated by insects.

8:48Jad Abumrad:Over time, he became a bug nerd.

8:50Robert Krulwich:Definitely a bug nerd.

8:51Jad Abumrad:Even named his cats after insects.

8:53Robert Krulwich:One after a mosquito and one after a boll weevil. Antonymous and Culex. And when he grew up. Grew up to be an entomologist. But also, kind of in the back of his mind, he was always thinking, well, I have to figure out a way to control screwworm. I want to put a stop to them somehow.

9:11Jad Abumrad:And as it happens...

9:13Robert Krulwich:The first job I had...

9:14Jad Abumrad:In the late 30s, he got a job at the USDA.

9:17Edward F. Knipling:As an entomologist working on the screwworm. That was the Bureau of Entomology and Planned Quarantine at that time.

9:24Jad Abumrad:And then... World War II breaks out. And the military enlists him in developing...

9:31Edward F. Knipling:Insecticides and repellents for use by the armed purposes. He actually ends up helping develop DDT.

9:37Robert Krulwich:Oh, yeah. Heard of that one.

9:39Edward F. Knipling:And this is actually sort of part of his journey, which is that he saw insecticides can be really effective, but they can also be really devastating for the environment.

9:47Jad Abumrad:So after the war, when he gets back to his screwworm job, he's just thinking about this problem.

9:52Edward F. Knipling:Like, how can we figure a way to control insects that does not require spraying lots of poisons?

9:58Jad Abumrad:And his way of trying to figure that out is watching screwworms mate. Just watching a lot of insect sex?

10:06Robert Krulwich:As one does? Like, yeah, why?

10:08Jad Abumrad:I think he was just trying to understand these pests, right? To think, like, what could we do about it? And so one day, a colleague of Nippling's is, you know, watching the screwworms have their sexy times, and he makes this observation. That sounds like maybe not that important or not that interesting.

10:24Robert Krulwich:But that kind of hinted at something. He wasn't quite sure what exactly.

10:31Edward F. Knipling:Which is that females only mate once.

10:34Robert Krulwich:Whether or not they get pregnant, they get one shot to have intercourse and try to have eggs.

10:42Jad Abumrad:I really feel for these females. Like, this is such a high stakes. You have to have the best sex of your life in that one time.

10:49Robert Krulwich:Yeah, that's it.

10:50Jad Abumrad:But Nippling, he's looking at this and he's like, wait. If he could just do something to all of the males, right? Like, if he could just make the males sterile. And then if he could trick the female screwworms into mating with these sterile males, the females aren't going to lay any eggs. They're viable.

11:06Robert Krulwich:That would essentially take those females out of circulation for reproduction purposes.

11:11Jad Abumrad:Their one shot would just be doomed to fail, basically.

11:14Robert Krulwich:Yes, exactly.

11:15Jad Abumrad:So just like somehow flood the zone with sterile males is the idea. These poor females already had it so hard, and now he's just like ruining the dating pool for them. It's a little diabolical from the fly's perspective. But lucky for these screwworm ladies.

11:31Robert Krulwich:It wasn't like that was a very practical idea.

11:33Jad Abumrad:Because how would you even pull that off?

11:35Robert Krulwich:You know, how do you mass sterilize a bunch of insects?

11:38Jad Abumrad:But then he finds a paper.

11:40Robert Krulwich:An article in Scientific Magazine.

11:43Jad Abumrad:Basically, since World War II, there's sort of like a lot of interest in like, what can we do with radiation?

11:47Edward F. Knipling:Oh, of course. Right. Yeah.

11:48Jad Abumrad:And this paper was by a geneticist who was saying that...

11:51Edward F. Knipling:It was possible to sterilize fruit flies by exposure to x-rays.

11:58Robert Krulwich:And I think he sort of jumped off of his couch and said, oh, my God. Maybe we could sterilize fruit worm. This could be the solution to the problem.

12:13Robert Krulwich:OK, so what? Yeah, what does he do?

12:15Jad Abumrad:Well, so the thing he needs is a bunch of x-ray machines.

12:18Robert Krulwich:But he decides he's not going to go public and try to get any funding for this. We knew that if the media got a hold of that, they could make quite a deal out of this.

12:29Jad Abumrad:I mean, remember, he's working for the government. Like, taxpayer money is at stake here. What happens if the press gets hold of this and then we're just totally ridiculed for, like,

12:37Edward F. Knipling:wasting money or something?

12:38Jad Abumrad:Watching and sex sex all the time. Not in a weird way.

12:42Edward F. Knipling:Yeah.

12:43Robert Krulwich:We were rather cautious about that. So he decides he wants to do this kind of on the down low.

12:49Jad Abumrad:And basically he gets one of his colleagues

12:52Robert Krulwich:to take a bunch of screw worms and sneak them into a nearby military hospital and use the x-ray machines there.

13:02Jad Abumrad:Flesh-eating worms in a hospital. Great.

13:04Robert Krulwich:Yeah, exactly.

13:05Jad Abumrad:But how does he get the screw worms in?

13:07Robert Krulwich:Unfortunately, we don't have many details about what he did to actually get inside there. I pictured him like hanging out at the loading dock at night and like grabbing the door right before it shuts. or, you know, like Watergate, like taping the lock or something like that, sneaking through the hall. I believe they did this at night, too. He had to be kind of clandestine about it, sneak around a little bit.

13:27Jad Abumrad:And they are literally like, you know, putting these flies through the next machine and be like, hey, what happens? But the problem with shooting a bunch of radiation at a bunch of flies is that you create all these mutations, a bunch of random mutations.

13:41Edward F. Knipling:So you might just kill the fly. That's kind of a problem. So they found that they figured out the right dose, but they also figured out exactly when to put them through radiation. It's when the flies' testes are developing, right? Because that's like what you really want to knock out. So that happens to be between 5.5 and 5.7 days.

14:00Robert Krulwich:So it's like they've got it to within hours.

14:02Jad Abumrad:Yes, yes. And when they do that, bingo. It seems to work. But...

14:09Edward F. Knipling:Of course, the next thing was when they perform in a natural population.

14:13Jad Abumrad:It's not enough to just do it in a lab.

14:15Robert Krulwich:So then he decides it's time for a real-world test, and he found an island off Florida. On the island of Sanibel. Sanibel Island.

14:23Jad Abumrad:He shows up there with some of the radiated screwworms from his lab, releases them on the island.

14:29Robert Krulwich:And it did not work.

14:30Jad Abumrad:Like, the population of screwworms stayed pretty much the same.

14:33Robert Krulwich:The experiment failed. And Nippling was glad he hadn't said anything or, you know, gone after public money.

14:38Jad Abumrad:So, yeah, does he just resign to his failure?

14:41Robert Krulwich:That's the end of the story, yeah. No, not at the end of the story. We were kind of stymied what to do for a year or so.

14:47Edward F. Knipling:And then I got a letter from a veterinarian on the island of Curacao.

14:54Robert Krulwich:A Dutch island called Curacao. Where is Curacao? Off the coast of Venezuela. He wrote a letter. And said, the goats here are being ravaged. I know you study this. Can you help us in any possible way?

15:06Edward F. Knipling:And I thought, well, this is just the place that we're looking for.

15:10Jad Abumrad:And this time, Nippling wants to go all out.

15:13Robert Krulwich:They were not going to take a chance that there would be too few flies.

15:18Jad Abumrad:Like, no more handful of flies from his rinky-dink lab.

15:21Robert Krulwich:They're going to set up an industrial facility for making these flies.

15:25Jad Abumrad:And, like, carpet Curacao.

15:27Robert Krulwich:And really overwhelm them with the sterile males to make sure that they were doing everything they could to give this experiment a chance of success.

15:35Jad Abumrad:So, in this factory that they set up.

15:37Robert Krulwich:They came up with a formula for the food that they were going to feed them. Okay.

15:42Jad Abumrad:And it was ground horse meat.

15:44Robert Krulwich:That they soaked in blood and they would let they get putrid. Wow. And then they would douse it with formaldehyde.

15:50Jad Abumrad:Okay. Wow. So, yeah.

15:54Robert Krulwich:And it was cheap enough to get, you know, so they knew they could produce a lot of this stuff pretty quickly. Okay.

16:00Jad Abumrad:Why the formaldehyde? I don't know why. That's such a weird...

16:03Robert Krulwich:Apparently they just liked the formaldehyde. I don't know. Oh, wow. That's just a little extra kick. It's like hot sauce for them. So then from about March 1954, they are producing 170 ,000 of these sterile adults per week.

16:19Jad Abumrad:They are feeding them this slurry, though at this point without the formaldehyde.

16:23Robert Krulwich:It took 40 tons of the slurry to get that job done. Wow. And it was a smashing success. The population plummeted after they started releasing these flies. His big idea had worked.

16:38Jad Abumrad:Back in the United States,

16:39Robert Krulwich:when the livestock people especially,

16:41Edward F. Knipling:ranchers catch hold of this. They came to us. And they're like, wait, we really want this.

16:46Robert Krulwich:Eventually, the clamor from ranchers got so big, Nippling decided, well, I think the time is right.

16:52Jad Abumrad:To try rolling out his screwworm strategy in the U.S. And so armed with some funding from the USDA.

16:58Robert Krulwich:This new technique for insect control is eliminating screwworms. The first big push started in about 1957. In Florida. And after about two years of dedicated work, they had eliminated them. Not just in Florida, but everywhere. East of the Mississippi. That is huge.

17:15Jad Abumrad:And then it kind of keeps going west. The Texas Cattlemen's Association hears about it.

17:20Robert Krulwich:I mean, it was a Texas-sized problem that they had.

17:22Jad Abumrad:They want him too, so Nippling and his team. Ended up building a really big factory in Texas. Screwworm Eradication Headquarters at Mission, Texas. Here millions of screwworm flies are being reared each day. All these, like, metal machines. Sarah told us about a similar factory she went to in her reporting. Many different rooms, sort of, like, all at different temperatures, different humidities for each phase of a life cycle.

17:45Robert Krulwich:I could not have imagined it smelled good.

17:46Edward F. Knipling:I'm sorry to say this, but what it reminded me of was the smell of a used tampon.

17:51Robert Krulwich:Okay, it makes sense.

17:52Jad Abumrad:Well, that's kind of a little bit bad, maybe. From these factories, they start releasing flies multiple times a week. So how do they do that? By airplane.

18:00Edward F. Knipling:These planes are being loaded with sterile male screwworm flies in Mission, Texas. Basically, they would fly these little prop planes and release these flies in the air.

18:10Robert Krulwich:They took them up in refrigerated boxes. They had to buy essentially cases of perfume and cologne and dump them on the boxes before the pilots would allow them in the airplanes. And then they would essentially open the hatch and just dump them out and let them fall down. Oh, wow.

18:28Jad Abumrad:And at this point... The nippling strategy is working so well, screwworms are disappearing from all of the Southwest.

18:35Robert Krulwich:They started marching their way down to the border, pushing it down, pushing it down.

18:39Edward F. Knipling:Eventually, people were like, well, screwworms obviously don't respect national borders. If we're really going to deal with the screwworm problem, we would have to enlarge the program. What if we just kept going? This operation can now expand into Mexico.

18:54Robert Krulwich:You know, get them out of Mexico. Then we go down country by country through Central America. That is so much ground to cover.

19:01Jad Abumrad:And so all through the 70s, 80s, 90s, there were all these kind of international agreements.

19:06Robert Krulwich:Frankly, this was a tough sell in some places because the U.S. has a history of meddling in Central America. Right. Especially in this time. But despite that, and despite political turmoil, revolutions and coups and things like that, the disgust over screwworms was enough.

19:22Jad Abumrad:That all seven countries in Central America came to the table.

19:25Robert Krulwich:And they started marching down, you know, a dozen miles at a time or so, just working down year by year, all the way down to the border between Panama and Colombia.

19:36Jad Abumrad:And in 2006, all of North America is declared screwworm free.

19:44Robert Krulwich:Wow.

19:45Jad Abumrad:And that so-called single most original thought in the 20th century changes the face of the entire continent.

19:50Robert Krulwich:Amazing.

19:51Edward F. Knipling:And to this day, at the time I was reporting it, there's still a factory in Panama. It's still producing millions of schoolrooms, growing millions of schoolrooms every day, flying a plane, I think it was three times a week, and maintaining this, basically this, what they called a bit like a sterile insect barrier.

20:10Jad Abumrad:The idea is that that area where Panama meets Colombia, the Darien Gap, which I think it's been in the news a lot for other reasons.

20:18Robert Krulwich:That's like the most dangerous area for migrants, right?

20:21Jad Abumrad:Exactly. But it's also one of the narrowest parts of the Americas, only about 60 miles wide.

20:26Robert Krulwich:Okay. So it's like a natural choke point.

20:28Jad Abumrad:Right. And because of that, maintaining that sterile screwworm barrier only costs$15 million per year,

20:36Robert Krulwich:which is a pretty reasonable price compared to the huge cost if screwworms were just kind of running wild.

20:43Edward F. Knipling:Yeah. So when I was preying on this back in 2020, the money saved was estimated to be over a billion dollars a year. So a billion dollars saved compared to 15 million cost. Wow.

20:52Robert Krulwich:So that's a pretty good return.

20:54Edward F. Knipling:And obviously it was more expensive when you were in the active eradication phase. Right. But the maintenance cost, you know, it's really not that much money for a government program. And it's just kind of an example of like how when with basic science, you don't always know exactly where it will go. But in this case, it ended up like creating this continent-wide multinational collaboration that has been going on for decades and decades. And the fact that this all kind of started with someone like watching squirrels meet in the lab and having an epiphany is kind of remarkable.

21:28Jad Abumrad:Now, there have been a couple of small outbreaks here and there over the years, including the Florida one, the key for 2016 one. Yeah. But they've all gotten tamped down pretty easily. Like, it didn't take all that much to beat those back. But when we come back from break, all kinds of things are going to break loose. News, biological barriers, and maybe also Latif's heart.

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24:59Robert Krulwich:This is Radiolab. I'm Latif Nasser here with producer Sarah Kari. Hello. And we've been talking to journalist Sarah Zhang and writer Sam Keane about screwworms.

25:10Jad Abumrad:Right. The skin-crawly, flesh-eating parasite that we all forgot about because nippling and hysterical flies drove it down south.

25:19Robert Krulwich:All the way to a biological demilitarized zone at the very bottom of North America, a.k.a. the southern border of Panama.

25:27Edward F. Knipling:Yeah.

25:28Jad Abumrad:But in 2023, Panama suddenly started seeing a massive spike in screwworm cases from like 25 cases a year to like thousands. And since then, it's only gotten worse. The parasitic fly is moving north.

25:48Robert Krulwich:They have been steadily marching north. They've been found in Costa Rica, Nicaragua, Honduras.

25:55Edward F. Knipling:El Salvador, Guatemala. They're even in Mexico. Only 700 miles from the U.S. border.

26:01Jad Abumrad:And it turns out it's basically getting closer every day.

26:04Edward F. Knipling:Less than 400 miles. 300 miles from Texas on the southern border.

26:08Robert Krulwich:It's gotten as close as 70 miles or so from the U.S. border. Whoa. This is an ongoing breaking news story. So what happened? Like, how did they get past the biological wall? There are a couple of theories.

26:22Edward F. Knipling:One theory is that maybe the strain of screw room that they were growing at the factory is not as effective anymore. I don't know, maybe the ladies out there caught on to what was going on and weren't mating with them or something.

26:33Robert Krulwich:Just general disruptions due to COVID might have weakened the production a little bit. Or maybe, Sam says, given that we live in a more and more interconnected world. Because it does still exist in South America, where people and products and animals are moving from place to place. It was just a matter of time before these worms found their way through. The best guess is that people were smuggling cattle that were infected, and then it just got out.

26:59Jad Abumrad:But regardless, as of today, right now, the screw worm, it's sort of like knocking on our doorsteps.

27:05Edward F. Knipling:It's not a matter of if the deadly pest gets to the U.S., but when.

27:09Jad Abumrad:And surprisingly enough, in this time of cuts to science funding and all that, and, you know, the idea of building political will around something that everyone has pretty much forgotten seems dubious. The issue has also alarmed Washington. It actually does seem like the U.S. government is paying attention.

27:26Edward F. Knipling:The U.S. Department of Agriculture has snapped into action.

27:30Jad Abumrad:And really, just like Nippling's time, pretty much because of the cattle industry.

27:33Edward F. Knipling:Billions of dollars of losses a year.

27:37Robert Krulwich:Of course.

27:38Edward F. Knipling:It could truly crush the cattle industry as well as other livestock industry in Texas.

27:44Jad Abumrad:So, the USDA has started to set up screwworm traps along the U.S.-Mexico border.

27:50Robert Krulwich:Shut down the southern border.

27:51Jad Abumrad:They have agents on horseback.

27:53Robert Krulwich:Those are so-called tick riders.

27:55Jad Abumrad:Patrolling the border for stray cows. They are pouring money into screwworm research. And of course, they are rebuilding Nibling's fly factories.

28:05Robert Krulwich:They are now building a new facility down in Texas.

28:08Jad Abumrad:Another one in Mexico. All told, probably in the next couple years, we will be producing and releasing something like 500 million flies per week. Wow.

28:20Robert Krulwich:Wow.

28:20Jad Abumrad:And we probably will have spent like hundreds and hundreds of millions of dollars.

28:25Robert Krulwich:Do you see this as like the modern cow factory farm system is like unsustainable? And like this is just like one other band-aid to keep that system financially profitable or something? Like I could see an argument that's like, oh, this is just to help like big rancher businesses.

28:43Edward F. Knipling:Yeah. Well, I think in a literal sense, like this program was created to help ranchers. That is, in fact, the express purpose of the USDA. So I think I wouldn't even argue with that premise. But this does affect wild animals, too. Right. In Central America, you used to see howler monkeys fall out of trees because they had become so disfigured and sick from getting infested by school worms.

29:06Jad Abumrad:And beyond that, I mean, actually, this time around with this effort, it's not just the USDA that's involved in this program. So I'll try and make the case on the human side of things. Number one. So I talked to this public health official named Megan Nichols, who is at the CDC.

29:23Edward F. Knipling:And my current role is incident manager for our New World Screwworm response.

29:29Jad Abumrad:Because the CDC is worried about this outbreak too. And the thing that Megan pointed out is that these flies like to infest a wound. I mean, you know, wildlife or cows aside, screwworms will happily lay their eggs in pretty much any warm-blooded animal, including humans. And it can be a pretty small wound, like as small as a little cut or a bite on the skin. I read that they can also get in through just like bodily openings. Is that true? It is true.

30:03Edward F. Knipling:They are often attracted to mucous membranes. So eyes, nose, ears, urogenital. Yikes. So yes. And during this outbreak, there have been over 1 ,000 human cases and the number continues to grow daily.

30:20Jad Abumrad:And to be fair, you know, like not to fear monger here, this is not a pandemic level human health crisis. Most people that take precautions will be totally fine. But I also think very much about this on an individual level. And the kinds of individuals that would be the most susceptible to a serious screwworm infestation, like folks who can't get medical help right away or people who are unhoused or have weakened immune systems or even like kids with a lot of scrapes.

30:46Edward F. Knipling:They're the last ones that need to deal with something like this.

30:49Jad Abumrad:And on the off chance that it does happen, it is kind of a horror show.

30:54Edward F. Knipling:One of the most impactful images that I have seen related to 2025 was patients that were lining the hallway of a medical treatment facility in a country that is currently part of this outbreak. and the patient was holding a bowl in which they were basically sneezing out and pushing out larvae from their nasal passage. And other people who were lining this hallway basically waiting to be seen because they were also needing to get the maggots out of their body.

31:26Jad Abumrad:Oh my gosh.

31:31Robert Krulwich:Okay, all right. I now I see the point that this is more than just the cattle industry. Yeah. But I do now wonder if it's just going to keep coming back. Like, is this just an inevitable cycle that we're now stuck in? Like, we're just going to have to keep doing this. Yeah, you kind of are on a treadmill. You're on a treadmill. Using Nippling's technique. Yeah. Yeah.

31:58Jad Abumrad:But I did, as I was reporting on this, come across a different way that people are starting to think about screwworm control.

32:05Robert Krulwich:So another option that is controversial, but scientists have been talking about it.

32:10Jad Abumrad:This is something that Sam mentioned, too.

32:12Robert Krulwich:Is something called a gene drive. Okay, so what is that? It kind of goes around the normal Mendelian laws of genetics.

32:20Jad Abumrad:Okay, so first of all, let's assume that you are a scientist that has modern-day genetic technologies available to you, and you introduce a killing gene into the screwworm population.

32:32Robert Krulwich:You could make it lethal to be a female, so it could trigger something where females just don't get out of the egg stage. It's like a little time bomb in the cell.

32:41Jad Abumrad:Yeah, exactly. And typically, if you were to try to do that, genetics would work its normal way. And that killing gene would only get inherited 50 percent of the time. And in every successive generation, it would become less and less common. And you'd have to keep reseeding that gene into the population. OK. But this is where gene drives have a little extra trick.

33:02Robert Krulwich:In a gene drive, there's closer to 100 percent chance that the gene will get passed down.

33:09Jad Abumrad:You can basically ensure that it'll get passed down every time. And so it's kind of like a set it and forget it kind of thing. Like you introduce the killing gene and then you just let it have its way with the screwworm population.

33:22Robert Krulwich:The screwworms are going to be out there reproducing and spreading that gene by themselves very quickly.

33:28Jad Abumrad:And what that really means is eventually...

33:31Robert Krulwich:It's going to wipe them out.

33:33Jad Abumrad:Not just, you know, beating screwworms back down to Panama, but like truly and wholly eradicating screwworms.

33:41Robert Krulwich:Extincting them.

33:42Jad Abumrad:Off of, extincting them off the face of the planet forever.

33:46Robert Krulwich:I just, well, like, I don't want us to have to live with these, but I don't want us to kill them forever. That feels wrong. That feels like we're doing something untakebackable that is not, that we should not be doing.

34:01Jad Abumrad:Yeah.

34:02Edward F. Knipling:Yeah.

34:04Jad Abumrad:But let me bring in one more person here.

34:06Edward F. Knipling:So I'm Greg Kaepnick. I am a research scholar at the Hastings Center.

34:12Jad Abumrad:Because I think he feels a lot of the same way.

34:14Edward F. Knipling:I mean, here we are in the early stages of the sixth major extinction, one that we humans are causing. And I mean, in a way, this seems like, gosh, joining forces with the other side in some way.

34:29Robert Krulwich:Yes, yes, exactly.

34:31Jad Abumrad:Well, but at the same time, Gregory has seen this potential use of gene drives coming on the horizon and really wanted to think about it more. So what he decided to do is get together a panel.

34:42Edward F. Knipling:I thought, I'll turn to some environmental ethicists.

34:45Jad Abumrad:Ecologists.

34:46Edward F. Knipling:Conservation biologists. Geneticists. Entomologists. Some people with a public health background.

34:51Jad Abumrad:No one from the Texas Cattle Ranchers Association.

34:53Robert Krulwich:We already know what they think.

34:55Edward F. Knipling:I thought it would be particularly interesting to bring together people who would be, by and large, kind of predisposed to want not to take out species. So? We gathered at Arizona State. In May 2024. For a day and a half of presentations and discussion.

35:15Jad Abumrad:They considered a couple of the top nasty species.

35:18Edward F. Knipling:Like the mosquito species that is the main vector of malaria.

35:22Jad Abumrad:And one of them was screwworms.

35:26Edward F. Knipling:Yes.

35:26Jad Abumrad:So the idea was to hash out some of the pros and cons for either side.

35:30Edward F. Knipling:You know, keep, eliminate, and sort of report out our findings.

35:34Jad Abumrad:And given the group of people that were sitting at the table, they started out with some of the arguments that you might expect.

35:40Edward F. Knipling:We need to think about the value of species.

35:45Jad Abumrad:Yeah, what do you mean when you say that?

35:47Edward F. Knipling:Yeah, I mean, there'd be different ways in which a species could be valuable.

35:51Jad Abumrad:Like, first off, there's some very practical ecological considerations.

35:55Edward F. Knipling:I mean, the main question is, what's it doing in the wild? You know, is it a pollinator? It turns out screwworm is something of a pollinator. Is it? Yeah, it is. Oh, my gosh. Yeah. But it's probably not a very important pollinator.

36:11Jad Abumrad:Okay. Bees do it better.

36:14Edward F. Knipling:Yeah, the bees probably win.

36:16Jad Abumrad:Then you have to consider whether some other animal needs to eat it.

36:19Edward F. Knipling:Probably. Sometimes.

36:20Jad Abumrad:But it turns out it's not really a key food source for any other animal.

36:24Edward F. Knipling:Is it? Does it play an important role as a predator in keeping other species in check?

36:29Jad Abumrad:I mean, obviously, in this case, yes, it is a predator.

36:32Edward F. Knipling:But according to Gregory, the animals it eats are already under pressure from human forces. So if anything, you want to ease the burden as much as you can on those species.

36:47Jad Abumrad:Okay, but they did also consider some more abstract values that a species might have.

36:52Edward F. Knipling:You know, aesthetic. Aesthetic, interesting. Educational, historical, scientific. I think that's the list.

36:59Jad Abumrad:Or maybe we put it in terms of screwworm. Yeah.

37:01Robert Krulwich:In my mind, I was thinking about it like if you were going around the way you did and you opened it up to all your colleagues and then sitting there was a giant screwworm. who is going to make the case to save itself. Yeah, like what's the best case that that screw worm would make? That's the hard case.

37:28Edward F. Knipling:Aesthetic, clearly. Educational, like don't mess with nature, kids.

37:35Jad Abumrad:You know, jokes aside, though, Gregory says, you know, people like him do actually put a lot of stock in the sort of intrinsic value of a species.

37:44Edward F. Knipling:It's this ingenious development in and of its own right.

37:48Jad Abumrad:You know, anything that's around today has been honed by millennia of evolution. And in that way, every species is...

37:55Edward F. Knipling:A marker of the creative, natural forces that sustain life, that brought us into being. I mean, I feel like you have to try to put it in a practically poetic way in order to really convey what people are thinking.

38:10Jad Abumrad:So Gregory's group, after about a day and a half of discussing all of this.

38:14Edward F. Knipling:We're all kind of exhausted and we're trying to, like, put it all together.

38:18Jad Abumrad:And Gregory says, okay, we're going to go around the room one by one.

38:22Edward F. Knipling:Sort of put everyone on the spot and see what they thought. And we did so. and by the time we'd gone around, everyone had, most people had, I think maybe everyone had actually said, yeah, screw worm looks like a pretty good candidate.

38:45Robert Krulwich:Really? Like that it would be okay to wipe this species off the planet forever?

38:52Edward F. Knipling:Yeah.

38:53Jad Abumrad:How did that feel? Is that awkward? um well i mean it was it was just like um it was kind of like this serious moment there was uh

39:05Edward F. Knipling:um everyone was sort of sighing like oh i really don't want to i really don't want to vote for this but but it looks like maybe the case can sometimes be strong enough but isn't there sort

39:19Robert Krulwich:of like i mean this just feels like you know an idea that always comes up with ecosystems like we think we know and then we don't like there's always the knock-on effects that we never see coming and we thought we knew everything but then it surprises us but there it is like does it does it not feel like hubris to assume that we know everything that could potentially go wrong yeah

39:42Edward F. Knipling:but we did in fact at least up until very recently get rid of screw worm in southern north america and throughout Central America, and, you know, the sky didn't fall. Other species didn't wink out because they weren't able to eat New World screwworm anymore. So we have a little bit of a kind of preliminary...

40:01Jad Abumrad:It's like experimental data.

40:03Edward F. Knipling:Yeah, kind of, like that suggests that it's probably not really that important ecologically.

40:12Jad Abumrad:So losing it, you know, doesn't seem to do any harm. And then on the other side...

40:17Edward F. Knipling:Part of what was so persuasive about it was that the death that it causes is exquisitely awful.

40:25Jad Abumrad:I mean, with screwworms, did you guys consider alternatives to eradication?

40:30Edward F. Knipling:Like if there were some other kind of treatment for it, some sort of medicine that you could take.

40:35Jad Abumrad:Gregory says if it was possible to, like, separate screwworms from the thing that they do or, like, the disease that they cause of, you know, flesh being eaten. And if you could attack that disease, then great. You know, like that's sort of the case with malaria and mosquitoes where you can attack the disease or in that case, the parasite rather than the mosquito. But with screwworms, there's just no way to do that. Like eating flesh is in their nature. It's what they do. There's just no way to make them like vegetarians or make them uninterested in flesh.

41:10Edward F. Knipling:The only way you get rid of the disease is by getting rid of the fly. At least at the time that we were meeting and writing, there was nothing else to do except take it out if you can.

41:25Edward F. Knipling:Illuminate the flies.

41:42Robert Krulwich:I don't know. I don't know. I want to agree with him, but I just I don't know if that wins the day for me. Like, I'm I don't disagree, but I just can't bring myself to agree.

41:54Jad Abumrad:No, this is, you know, this is the part of the story where I feel like I agree with you. I don't know. I don't know what to do with the fact that I don't want screw worms to exist. you know like i i think about like the people in south america we just stopped at panama like i don't know i don't want them to have to deal with screw worms and suffer and but at the same time this this stuff gets scary i i guess one thing i will say though um that gregory did mention uh is that if we go down this path yeah theoretically there is sort of an undo button here you can

42:34Edward F. Knipling:definitely keep it somewhere else in a facility or, you know, frozen eggs or something. And if it were to turn out that...

42:44Jad Abumrad:Like the cure for cancer was in the screwworm eggs or...

42:48Edward F. Knipling:Really vital to the life cycle of this frog species in South America or something like that.

42:55Jad Abumrad:Some ecological Rube Goldberg machine got set off because we got rid of all the screwworms.

43:02Edward F. Knipling:Yeah. It would be possible to achieve something like de-extinction with screwworm.

43:08Robert Krulwich:To bring it back, to seed it, fling it out of the planes the way we're flinging out the sterile ones.

43:12Edward F. Knipling:Yeah. And what we know from the outbreak in Central America now is that it can take off pretty well.

43:23Imagine the public campaign

43:26Robert Krulwich:where it would be like, hey, everybody, remember how we... Remember how we...

43:33Jad Abumrad:to exist.

43:34Robert Krulwich:There's this one frog in Panama that this was really helpful for. So we're just going to drop these flesh-eating worms. We're just going to rain them down over you and your home.

43:46Jad Abumrad:Yeah.

43:50Robert Krulwich:So one last thing before we go. Back in 2016, Edward Nippling and his screwworm research won a Golden Goose Award. If you haven't heard of it before, the Golden Goose Award goes to U.S. government funded science that sounds ridiculous, but ends up changing the world. And Nippling's research was exactly that. Even years after it proved useful, members of Congress still ridiculed and scapegoated it. Frivolous pork projects such as the screwworm research, $35 million. As an example of government waste. Even though the screwworm has been eradicated

44:24Jad Abumrad:in the United States.

44:26Robert Krulwich:This is now the fourth Golden Goose inspired story that we have done. We did one about cone snails called golden goose, one about a bacterium called the age of aquaticus, and one recently about honeybees called time is honey. And now this one, it's almost become like a sneaky little recurring series that if you ever meet someone who doesn't believe that the government should fund basic science, just play them one of these. We'll link them all in the episode description.

44:54Jad Abumrad:This episode was reported and produced by me, Sarah Kari, with reporting help from Latif Nasser. Our fact checker was Emily Krieger. Check out Sam Keen's podcast, The Disappearing Spoon. His episode about screwworms is linked in our episode description. Same goes for Sarah Zhang's latest story in The Atlantic. And if you are interested in hearing more about Gene Drives, check out our episode about it, the last 10 minutes of our CRISPR update.

45:18Robert Krulwich:Thank you to James P. Collins, Max Scott, Amy Murillo, Daniel Griffin, Phil Kaufman, Katie Barnhill, Arthur Kaplan, Ron Sandler, Yasha Rower, and our gaggle of friends at AAAS who administer the Golden Goose Award, Aaron Heath, Gwendolyn Bogart, Valeria Sabate, Meredith Asbury, and Joanne Padrone Carney.

45:37Jad Abumrad:And the last, last thing, if you want more information on screwworm infested areas or how you can take precautions to be safe, there is a website you can check out. It is screwworm.gov.

45:49Robert Krulwich:That's screwworm.gov. Um, sorry, I guess it's time for us to just screw off. Indeed. And we'll catch you next week.

45:58Jad Abumrad:All right.

46:13Edward F. Knipling:Hi, I'm Gabby. I'm from San Francisco and here are the staff credits. Radiolab is hosted by Lula Miller and Latif Nasser. Soran Wheeler is our executive editor. Sarah Sandback is our executive director Our managing editor is Pat Walters Dylan Keefe is our director of sound design Our staff includes

46:47Edward F. Knipling:With help from Gabby Santas Our fact checkers are Diane Kelly, Emily Krieger, Natalie Middleton, Anjali Mercado, and Sophie Semayi.

47:02Edward F. Knipling:Leadership support for Radiolab's science programming is provided by the Simons Foundation and the John Templeton Foundation. Foundational support for Radiolab was provided by the Alfred P. Sloan Foundation.

47:51Edward F. Knipling:WNYC Studios is supported by the New York Phil.

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