Unexplainable - Dropping like flies

Episode Date: May 25, 2022

Insect populations are shrinking all over the world, and entomologists are buzzing with questions: Why is this happening? How quickly? And, most concerningly, what does it mean for food supplies or even life as we know it? For more, go to http://vox.com/unexplainable It’s a great place to view show transcripts and read more about the topics on our show. Also, email us! [e-mail] We read every email. Support Unexplainable by making a financial contribution to Vox! bit.ly/givepodcasts Learn more about your ad choices. Visit podcastchoices.com/adchoices Learn more about your ad choices. Visit podcastchoices.com/adchoices

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Hassenfeld. And this week, we've got a story from reporter Bird Pinkerton about something that might bug you. Akito Kawahara loves bugs so much that he studies them for a living. But if you do not share his love for creepy little six-legged things, he can empathize. Yeah, when I was a kid, I actually hated insects. But then when he was five or six, his dad bought him a little green butterfly net and took him out to look for butterflies. This is the 1980s. They're in central Tokyo, which is. is not the best butterfly hunting spot

because it's in the middle of the city. But even so, on their very first outing, this rare bug landed in front of them. A special species of something called a snout butterfly. They're funny-looking. They're weird-looking butterflies. Picture like a medium-sized, reddish-brown butterfly, splashes of orange and white on its wings,

and then this long, thick snout, like an ant-eaters. And I remember just seeing it. And my heart was racing, and I, like, slowly crept up my net. I mean, it was just incredible. That experience sold to keto on the fundamental magic of insects, like the weird beauty and joy of them. And then, as he kept collecting and eventually studying bugs,

he learned that insects kind of make the world as we know it possible. People don't realize that many of the things that we find in our grocery stores are there because of insects. Basic things, like oranges, Apples. Cucumbers. Blueberries. Tomatoes. Even potatoes. Insects pollinate all these things. So the grocery store would be at a pretty depressing place without their help. Chocolate exists because of insect pollination.

Bugs also turn garbage into rich soil that we can use. Decomposition is a huge, huge thing. So there are these flies and beetles and other things that decompose, and they're getting rid of a lot of our things that we otherwise would not be able to get rid of. And then they feed lots and lots of. lots of animals. So songbirds rely on insects as food. So all the little warblers and things like that that you see in your yard, they would not be there.

Bugs are basically the bees' knees. Like, in a world without a rich diversity of insects, we could have a serious problem in our food chain. We could lose the bottom of the food pyramid for a lot of different ecosystems. And a lot of garbage might not get broken down. And unfortunately, a world without a rich diversity of insects is looking more and more likely, because the bugs are not all right. Scientists from many different countries across the world are kind of coming to the same

conclusion that insects are disappearing, and they're disappearing pretty quickly. It is a really serious situation. This week, Ununexplainable, why are so many of the Earth's bugs dropping like flies? And how do we stop that from happening? The idea that we're losing some bug species is not actually new. Like, scientists have known for a while now that individual bug species are endangered, just like individual mammals or fish are endangered. In the early 2000s, Akito himself actually wrote a paper about a specific endangered bug, another snout butterfly from French Polynesia. But he says that when he was starting out his career, entomologists weren't really zooming out to measure the health of bug populations on a national or international scale.

You know, nobody had sort of quantified that in any way. Until somebody did. Yeah, there was a very important paper that was published in 2017. This was a study done in Germany by a long-standing group of bug collectors, some scientists and some very devoted amateurs. And what they did was they set these traps up that catch insects that are flying by and so forth, and they fall into this little bucket. And they just basically counted everything. And they looked at the weight, you know, the biomass of the stuff that's in there. So these German bugners, they were basically putting all the bugs they were catching on a scale,

using that total weight of bugs to get an approximate sense of how many bugs there were. And they were doing this big weighing up of bugs at a bunch of sites across the country over and over again over the course of 27 years. And what they found out was pretty incredible. They found that the weight of winged insects was down by more than 75%. Like, if you took the overall weight of winged insects collected in their traps in the 1980s and then compared that to the weight of winged insects three decades later, there was something like a quarter of the insects that there had been before. And it was even worse in their midsummer measurements where the weight of the bugs was down 82%.

82% correct. These researchers weren't sure why this decline was happening, but they were pretty confident that in less than three decades, these German test sites had lost most of their winged insects. And that was what they were putting out into the world in this paper. I was shocked. I could not believe it. I read it many, many times now.

And just because it's so eye-opening. So researchers like Akito, they were suddenly realizing that they couldn't just focus on a few endangered species of butterfly and French Polynesia anymore, right? because this paper was about really common insects. And it could be signaling a decrease in all bugs. We're talking about the abundant species. We're talking about all of the bugs that pollinate the flowers in just your backyard.

This is Dave Wagner. He's been a biologist for decades. He used to focus on sort of reconstructing the tree of life. But then he read this paper in 2017, and it really shook him. Basically, I've changed my whole scientific career. Now, Dave focuses almost completely on insect decline. Akito has also started doing more and more research around this. And this paper wasn't just blowing entomologist minds and making them rethink things.

Other scientists were also passing it around, and a buzz was really starting to build. But it was really Brooke Jarvis's article about that study in the New York Times magazine that was the explosion, the shot hurt around the world. Coming up, the insect apocalypse, why a thinning bug population is keeping scientists up at night. Insects, they are vanishing by the millions. Buzz, buzz, buzz, someday we'll miss these bugs. As the news spread, so did the research interest.

And in the next few years, more papers came out. And they also found that insects are on the decline in various parts of the world. They started suggesting theories about why this was happening, like climate change, is destroying insect habitats, and they started throwing out more scary numbers. Human activity could drive the Earth's entire insect population to extinction, according to a major new scientific study.

The report says more than 40% of bug species face extinction. Overall, the mass of insects is falling by 2.5% every year, meaning they could vanish within a century. These are frightening numbers with pretty frightening consequences. Scientists say this could destroy the way all ecosystems function, affecting all life forms on the planet. With 75% of our crops needing insect pollinators, and insect apocalypse could seriously affect the world's food supply.

What we can be sure of is that we are moving in the direction of a collapse of ecosystem services that will take civilization down right along with it. If the insects disappear, we're going to disappear too. But Akito and Dave, they're not quite so sure about this sort of insect apocalypse framing here. Like, they're very glad these studies have brought attention to this issue, but they're a little skeptical of the claims that we're going to lose all the insects in the very near future. As a scientist, we have to make sure that we don't overstep the data and oversell the case. You can't say that the sky is falling at a clip and find out that it's only going at half that speed or a third that speed because then science loses its credibility. Dave says that the German study is really meticulous, really solid, and since then there have been more than 40 studies that he finds really compelling, mostly out of Germany and the UK.

And these are studies that look at different habitats, they use different methods, they study different types of bugs, and they all find insect declines. But there are other papers, some of the papers actually with the scariest numbers, that he says have some flaws. Like, one of them had six rebuttals published against it, which is not normal in the world of bug research. So Dave says that some of the numbers here, like we're losing 40% of all insects in 30 years or we're losing 2.5% of insects every year. Those might be a little high. He says it's more likely we're losing maybe like 1% of all the insects every year, which would still be a huge problem. It takes a long time to see a 1% decline. But of 1% the client is enormously important in that just after a decade, we'd be missing 10% of the tree of life.

But even that 1% number, it's a guess. And to Dave, that's the big problem here. Like both he and Akito agree that we are losing insects, that it will have consequences for us for the planet. But they say we need much, much better data about which insects we're losing and where we're losing them so that we can figure out what those consequences will be for our food supply and for animal ecosystems. Like, the studies that we currently have just leave us with huge gaps in our fundamental knowledge about what is going on. What are the rates to the decline? Are they happening just in Germany where we have four or 500 people living per square kilometer?

Is it happening in the tropics? Like, we don't know what is happening in terms of biodiversity loss, how much we're losing, and how much is that going to affect us as human beings? And they also want to answer the most critical question of sort of why this might be happening. Because right now, there's no clear culprit. It's death by a thousand cuts, and it's not one single stressor. It might be two or three or four, or five, or six stressors. Climate change is probably one of those big stressors, for example,

because it's changing insect habitats. Humans are also destroying more insect habitats through sort of construction and pollution. our street and houselights can attract bugs and disorient and kill them. Pesticides can kill them too. It's just one thing after the other, and it's therefore very hard for a scientist to identify a single stressor. All these questions are part of a much bigger issue that researchers run up against when they try to study bugs.

We just don't know anything about them still. After the break, why it's so hard to understand bugs and how researchers are working against the clock to figure them out. It's all about you. And when you fly with Virgin Atlantic in their upper class cabin, they take the VIP treatment to the next level. With a private wing to check in and your own security channel at London Heathrow,

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To put AI to work for people, visit service now.com. Bug it now! Okay, unexplainable. We're back. I'm Bird Pinkerton. Before the break, we heard from two entomologists, so Akito Kawahara and Dave Wagner. And they explained that ever since 2017, researchers have been really worried that bug numbers are dropping fast.

But when they try to figure out how fast exactly and which places are most affected, that's when things get hard. Because, as Akito says, it's kind of hard to know how many species you're losing when you don't know how many species of insects there are to begin with. So this is actually one of the big questions that's out there. The current estimate, the one that a lot of people are now going by is about 5.5 million. But there's also numbers that range from like one million all the way up to maybe 50 million or so. If you dig into where these sort of numbers or guesstimates come from, it really gives you a sense of exactly how little we know about insects and why we know so little. One guest that got cited for a really long time came about in 1982, for example.

What happened was researchers analyzed one specific species of tree in Amazon, and they counted the beetles on that tree. They use these foggers and stuff, so there's like these smoking devices and like the bugs like fall out of the trees and stuff and you like put like your tarp down on the bottom. They counted up the beetle species that they found on those tarps. And basically one guy did some very speculative math. He was essentially like, okay, there are this many beetle species on this tree. Maybe like 50,000 trees in the tropics. So like I'll multiply this number by 50,000.

I'll do a bunch more math like this. And eventually he came up with this guess that there were maybe 30 million species of arthropods worldwide. Nobody knows if that's even correct, but those are the kinds of attempts in the past that have been made. And if that seems wildly imprecise,

it's because it's wildly imprecise. But if you wanted to get a much better number, like an accurate count of all the bug species around the world, you'd really need to put in a lot of work. because first you'd have to be ready to count a lot of bugs. So you'd need a lot of people or you need a big team to kind of figure out what's going on? And those people would need to be ready to count bugs that are very small. The ones we see like monarch butterflies and beetles and dragonflies and stuff like that, those are the big ones.

The small things are like the things that live in the soil that we don't really, I mean, you need a microscope to look at. But even if you did get sort of one perfect count with sort of all the species identified, Dave Wagner says that that's still not enough. Well, one of the biggest challenges of studying insect populations is they boom and bust from year to year or even generation to generation. So think about like cicadas, for example, right? They're MIA for 17 years, and then suddenly they're everywhere. And other insects will have sort of wild population swings that they use to throw off predators.

But if those are the life cycles and how things are happening, it's very hard to measure those. So you could take 10 measurements and not know whether a species was declining or increasing. So it's a very hard problem, right? But don't worry. It only gets harder. Because even if you did do a really good count and you did it often, you'd also need to make sure that you were doing it all over the world. To get a global number, you need global data. And researchers just don't have that yet.

Completely. There's a huge bias in geographic areas that have been studied. So the majority of studies where these predictions of insect declines have come from are places like Europe and the United States. But when you look at biodiversity and where insects are the most abundant, it's not these places. Insects are the most abundant in the tropics. The big, you know, the $25 million, billion dollar question is what's happening in the tropics. Because that's where the cradle of biodiversity on the planet is. 80%, 85% of the species in the world may live in tropical.

regions. So just to recap here, based on the studies we have so far, which aren't always perfect and don't currently cover the whole planet, insect numbers are dropping off in some places. It's pretty clear that that is going to have consequences for ecosystems, the birds, the bats, the fish that depend on insects. It could have serious consequences for our food chain, since insects pollinate so many of the crops that we need to survive. But before researchers can tell us, exactly what those effects might be. They need to know how fast we're losing insects. They need to know which insects we're losing,

whether we're losing more in places with lots of people like Germany, or if insects are dropping off in the tropics as well. And all of this is really hard to do because insects are infuriatingly difficult to pin down and study. So what does that mean there's nothing that we can do? No, there's always things we can do. So that's the most important message in this phone call is there's only solutions. Ever since that German paper in 2017, the scientific community really has mobilized to fill in these gaps.

There's more funding to try and answer these questions. And there's more people who want to answer them. Oh, there's been a sea change in interest. So there's quite a few people that are analyzing old data sets, and there's many, many new monitoring studies being kicked off. and many young people, PhDs and early career scientists that are looking at insect declines. More research is happening in the tropics now. And scientists are also exploring new ways of getting at the answers that they want,

things that could get around the problem of sorting through thousands of dead bugs by hand. So, for example, they're trying to analyze river water for traces of bug DNA to see if they can use that to kind of get a picture of insect diversity in a region. So the possibilities in the future are very exciting and limitless, but certainly things are going to be changing. And while this research landscape changes, it's not like we need to sit around and kind of twiddle our thumbs. Akito has devoted a lot of his career to figuring out what we can do right now to help bugs out. And he says that at the highest levels of government and policymaking, like elected officials can push for climate-friendly policies, more natural spaces for bugs. bugs. Local governments can also make really meaningful changes, like take, for example, the

problem of light pollution. Leaving on lights can kill insects because they're attracted to them and they end up dying. But in places like Europe already, they've, they're shifting the wavelength of the light bulbs that are used on streets, for example, away from the ultraviolet spectrum towards the more infrared spectrum, because we know that that is a wavelength that's going to attract insects less than the other. But there are also things that individual people can do. So if you have a house, for example, and that house has a lawn, you can do a lot to help bugs out. When you're looking at it from the insect perspective, lawns are simply, you know, they're deserts.

There's nothing there. This is not good. But you could make it good if you stop mowing your lawn. Or if that's not an option because you don't want to, like, cheese off your neighbors, you can stop mowing just a part of your lawn. convert just a little bit of your lawn just into a natural space that is not mowed and is allowed to grow in its sort of natural way those are going to create little stepping stones for birds and insects and all kinds of other things that will come there and it will help protect the environment and if we just did even 10% of our lawn this would be enormous and you'd be saving costs because

you wouldn't be calling a mower to mow that area of space So if you have a homeowners association, I don't know, go tell them that you need your lawn to look very wild so that you can help out migrating insects that are really critical for our food supply or even just help insects that feed your local ecosystem. And if like me, you don't have a house with a lawn, then maybe just try to spread the good word about insects. Like, obviously, yes, there are still mosquitoes carrying deadly diseases. I doubt I'm ever going to be a huge fan of cockroaches. But Akuto says that we could accomplish a lot if people didn't just focus on the kind of gross or horrifying things that bugs do and instead also celebrated the wild and amazing stuff they can do. Insects are so fundamentally important in terms of understanding flight and movement

because they are able to do things that we typically can't even imagine. Literally, bugs are our tiny superheroes. Dragonflies can see almost 360 degrees. And they can see the front, they can see the back, they can see the sides. And they have hundreds of different lenses. And they're processing all this stuff really quickly, and they don't fly into anything. Nocturnal bugs do wild things too, like cockmoths, for example. They can see color in extremely dim light, and they're just flying through the jungle.

and they never hit any object, and they're able to find the flowers and the other things that they're looking for. And it's not just that this is really cool. Like, bugs can also teach us about their superpowers. A lot of the drones that we're designing and, you know, all these kinds of things that are being put together,

they're done because scientists are studying how insects move. So there's so much we can learn from insects themselves. So to Akito, insects are like books in a magnificent, planet-wide library. And right now, we have millions and millions of these insect books on our shelves, just sort of waiting to be read and explored. He really wants people to fall in love with those insect books, to enjoy them.

But he also wants us to know that unless we do something about it, that bug library is just going to keep shrinking. The books are disappearing off of the bookshelf. as time goes by. Many of them are still there, but they're sort of slowly slipping away. And what I fear as a scientist is that eventually there's going to be

a bookshelf or a wall of bookshelves where there's very, very few books left. Thanks again to Akuto Kawahara and Dave Wagner. Speaking of books, there's a new one out on this subject from Oliver Millman, who's an environmental reporter for The Guardian. It's called The Insect Craigslist.

and our biodiversity reporter Benjee Jones interviewed him for the site about it. You can find that interview at Vox.com slash unexplainable. Meanwhile, this episode was produced by me, Bird Pinkerton. It was edited by Catherine Wells, with help from Meredith Hodnott, Brian Resnick, and Noam Hassamfeld, who also scored the episode. Richard Seema, checked the facts. Christian Ayala and Afim Shapiro were on mixing and sound design. Manning Nguyen was really, really correct about how good everything, everywhere all at once is.

If you want to convince me that I am incorrect about cockroaches, for example, or have ideas for unexplainable stuff that we should cover, please email us. We are at UnexPlanable at Box.com. Or you could leave us a rating or a review. That would be very nice. Unexplanable is part of the Vox Media Podcast Network, And we're off next week, but we'll be back the week after that.