Short Wave - Can A Low-Carb Diet Prevent A Plague Of Locusts?

Episode Date: January 22, 2020

Swarms of locusts can destroy crops and livelihoods. Right now, countries in East Africa are dealing with the threat. At a lab in Tempe, Arizona, researchers are trying to figure out how to minimize the crop damage these voracious pests can cause. The answer, NPR's Joe Palca tells us, might be looking at what locusts like, and don't like, to eat. Follow host Maddie Sofia on Twitter @maddie_sofia. Email the show at [e-mail] pcm.adswizz.com for information about our collection and use of personal data for sponsorship and to manage your podcast sponsorship preferences.NPR Privacy Policy

You're listening to Shortwave from NPR. Joe Palka, are you prepared? Are you ready to go to Locustown? I am, Dr. Maddie Sophia Person. Go ahead. Okay, Joe Palca, you were in Arizona visiting kind of an unusual lab. Yes, I was. I was in a lab in the middle of Tempe, Arizona that's filled with locusts.

Locusts. Locusts. My understanding of locusts is very biblical, like, terrifying, swarmy. That's the locust we're talking about. But they're not just biblical because today, as we sit here in Studio 44 in Washington, D.C., there are major issues. For example, in Kenya and Ethiopia and Somalia, there are huge swarms of locusts. And these swarms, according to the Food and Agriculture Organization of the United Nations,

are, quote, extremely alarming and represent an unpubstant. unprecedented threat to food security and livelihoods in the region. So how do we fight it? So the problem is you can't spray them into submission. I mean, there's too many of them. It's too big an area. It's a lot of pesticides. So what they're trying to do at the lab in Arizona is come up with other ways.

And one of them has to do with what locusts like to eat. So today on the show, how do you prevent a plague of locusts? The solution could be a low-carb diet. Okay, Joe, let's start with some basics. What is a locust? It's an interesting question because here's the mantra that you hear from every locust researcher I've ever talked to. And here it goes. All locusts are grasshoppers, but not all grasshoppers are locusts.

Uh-huh. Uh-huh. You got it? Okay. So what does that mean? Well, it turns out there's something like 20,000 species or some number like that of grasshoppers in the world. And only about 19 of them can become. locusts. And what happens is there's a change, a physical change in the brain, in the wing

size, in the coloration that happens because certain species of grasshoppers, when you pack them together, literally just pack them together, grow them up in litters like you would, puppies or something like that, they turn into this thing that we know as locust. So a locust is just a type of grasshopper that gets really close to their grasshoppers and gets real riled up. Yes. They call it duct. Dr. Jekyll and Mr. Hyde. I will never look at my neighborhood grasshopper the same way. The grasshoppers you're going to see in your backyard, you don't need to worry about

because in the United States of America, there are no locust species. And it wasn't always the case. So the woman who runs this lab in Arizona is a woman named Ariane Sees, and she's head of something called the Global Locust Initiative. And she told me about the biggest locust swarm ever recorded. And you know where it was? Where? In this country.

Oh. The largest swarm ever recorded was the size of about the state of California. That is so gross. So you had swarms flying overhead for days. And whenever they landed, they pretty much ate everything. It was really devastating. So did you read the Laura Ingalls Wilder Little House on the Prairies book? I think I did.

Well, there was one of them where she talks about this. Well, she called them grasshoppers. In fact, they were locusts. They called the Rocky Mountain Locusts. that devastated the farm that she was growing up on. Could you imagine them just swarming overhead for days? No, I do not like that. I'm not comfortable with that.

But that's what got me intrigued? Because, I mean, what? I never heard of this. And it turns out that the Rocky Mountain locust did this in the 1870s, and everybody thinking, oh, my goodness, is this going to happen again? Are we going to have our crops wiped out? And the answer was, well, no, it never did. And they don't know why.

And then sometime in the early 1900s, this locust was declared extinct. Do we know why it went extinct in the United States? Good question. The answer is not for sure, but Ariensis thinks. It's most likely due to human use of the landscape with bringing in lots of cows, for example, tilling areas that hadn't been tilled before and potentially disrupting egg beds. And that interfered with their ability to survive because they're gone. And in a way, that leads to some of the things that she's most interested.

in the work that she's doing in Arizona because they're trying to figure out ways of changing human behavior in a way that will affect locust vitality. All right. So take me to their lab. Well, the lab is into the basement of a building. And there's a keypad, right, because they don't want people wandering into the locust lab, but even more important, they don't want anybody wandering out. because these guys are a potential pest, and so there's a lot of barriers to keep them from going. So I was at the lab, and the lab research manager, a guy named Rick Overson, took me in and showed me around. So we are inside one of the two main rooms of the Locust Lab

here at Arizona State University. We affectionately refer to it as Hoppertown. Hoppertown. It's almost like it's not full of a plague. Yeah, well. But anyway, they have these rooms, and they have a lot of cages with this metal mesh in the front, and you can see locust. So this is the locust colony, so one of these environmental chambers we use. And these are big honking insects. They're about five inches long.

He offered to let me handle one. Frankly, I wasn't really up for it. When you grab them, they try and use their legs as a defense mechanism and kick. Wait, you didn't pick one up? No, Maddie. I did not. Come on, Pelka. You're in the, you're in Hoppertown.

I am not into immersion reporting. But I got really interested in, you know, how do you maintain a colony of locusts? Like, what do they even eat? Well, it turns out that most of the colony eats this stuff called wheatgrass, which you get in your juice bar. So they grow a ton of wheatgrass. But they're also interested, and this is where the control aspects comes in, but they're also interested in making a special locust chow. We have a full range of them that span from very sugary,

so very carbohydrate-rich diet. You could think of it kind of like donuts all the way through a spectrum from a balanced diet to then a very protein-heavy diet that would have lots of like weigh protein in it, for instance, kind of like a bodybuilder shake. Okay, so these locusts are either eating donuts or protein shakes. I am really starting to identify with this calco. We know which one you'll be going for.

These are two ends of a spectrum. There's either a high protein diet or a high carbohydrate diet. So you've got the steak diet or the donut diet. And the reason they're interested in this is they think that they can establish that locusts have a particular affinity for the carbohydrate diet. So what's the significance of that for controlling them? Like what's the real world application for that? So the real world application comes because of what they're growing in Senegal. What are they growing?

They grow a lot of millet, and that's a grain. And if you grow the millet in healthy, well-cared-for-soil, you get a millet that's high in protein. And if you grow it in poorly cared-for-soil, you get a millet that's high in carbohydrates. And the locust love high-carbohydrates. Right, exactly right. They love that donut diet. And so if the farmers can be talked into keeping their fields in good shape by fertilizing them and making sure there's not a lot of runoff and stuff, then they will be growing a crop that the locusts are less likely to eat. I mean, would this have to happen on like a big scale?

How realistic of a solution is this? Well, that's the big question. I mean, here's what Ariens lab has been able to show up to now. that in the lab, locusts prefer a high-carb diet. And in places like Senegal, locusts tend to show up in poorer quality fields where the millet has a higher carb content. So the next step is to see if helping farmers take better care of their fields, which creates millet with higher protein and less carbs actually makes a difference

and keeps the locust at bay. Now, will doing this help farmers against a megast swarm of locust? No. When they're hungry, they're going to eat everything. But it should help manage infestations short of a cataclysmic plague. And I'll tell you what, I'll come back in 10 years and let you know if it works. Okay. Joe Palka, NPR Science Correspondent and Locust Enthusiast.

Joe works on a project called Joe's Big Idea, which examines the minds and motivations of scientists and inventors. This episode was produced by Rebecca Davis, edited by Viet Le, and fact-checked by Emily Vaughn. I'm Maddie Safia. This is NPR's shortwave. We'll see you tomorrow.