Plot twist: We're probably way undercounting insects on Earth

Maybe you’ve wondered about it late at night as a mosquito buzzes in your ear. Or when you kick over a rock and watch dozens of little critters crawl away: How many types of insects are there in the world? Scientists have been interested in answering this question for years. A new study — based on a census of tiny and, frankly terrifying, parasitoid wasps — suggests there’s way more than previously thought. Like, millions more that are just waiting to be discovered. Interested in more bug science in the news? Email us your question at [email protected] mailto:[email protected]. Support public media with NPR+ and enjoy perks for over 25 podcasts like this one. It includes perks like bonus episodes, early access, archive access, curated playlists and sponsor-free listening. Learn more at plus.npr.org http://plus.npr.org. See pcm.adswizz.com https://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 https://www.npr.org/about-npr/179878450/privacy-policy

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• 0:00Speaker 00

  This message comes from Planet Visionaries. Host Alex Honnold sits down this season with extraordinary doers, creating real climate solutions. Listen or watch wherever you get your podcasts. You're listening to Short Wave from NPR.

• 0:17Regina Barber?

  Hey, Short Wavers, Regina Barber here.

• 0:19Speaker 02

  And Nate Rutt.

• 0:20Regina Barber?

  With our biweekly science news roundup, featuring fellow space nerd Scott Detrow of all things considered. Hey, Scott.

• 0:26Speaker 03

  I am slumming it here today, talking in an episode that contains non-space news, but I'm doing that for you.

• 0:33Regina Barber?

  Excellent. We're going to talk more about space next week, too. But this week, we've got a few mysteries unraveling. First up, how many different types of insects are there on the planet? Scott, do you have a guess?

• 0:45Speaker 03

  Like, overall, raw total? Or like species?

• 0:48Speaker 02

  Species.

• 0:49Speaker 03

  OK, I don't know.

• 0:53Speaker 03

  Four million? I don't know. I don't know. A lot.

• 0:57Speaker 02

  Well, you didn't go over. I'll give you that.

• 0:58Regina Barber?

  We're going to tell you.

• 0:59Speaker 02

  Quick side question, just because I'm a nerd. Do either of you guys have a favorite insect?

• 1:03Regina Barber?

  Yes.

• 1:04Speaker 03

  What's yours?

• 1:04Regina Barber?

  It's a firefly, because I never saw them on the West Coast until I moved to the East Coast. I like them.

• 1:08Speaker 03

  Oh, I was going to say firefly.

• 1:10Regina Barber?

  Oh, we're the same.

• 1:11Speaker 03

  Fan favorite.

• 1:11Regina Barber?

  We're the same.

• 1:13Speaker 03

  Let's get firefly tattoos.

• 1:14Regina Barber?

  I was literally looking up during the Fourth of July, and I was looking at all the stars. We were out away from city lights, and I saw the stars, and I saw fireflies in the trees. It was so cool.

• 1:23Speaker 03

  What a win.

• 1:24Regina Barber?

  I know. Speaking of astronomy, you know, see, that was my segue. We have another story that looks at quasars, bright lights from ancient galaxies. So these are really, really old fireflies that can tell us more about the formation of the universe.

• 1:38Speaker 02

  Yeah, and the final study looks at the, let's say, unfortunate eating heads of California wolves. You are listening to Short Wave, the science podcast from NPR.

• 1:59Speaker 04

  Stay tuned for the following announcements and messages from our sponsors.

• 2:03Speaker 00

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  being rich is knowing what counts. Let's find your rich together. Edward Jones. Member SIPC. This message comes from Planet Visionaries. If you're looking for a dose of optimism, Planet Visionaries is the podcast you need. Host Alex Honnold sits down this season with extraordinary doers creating real climate action. It's a lineup that proves hope isn't naive, it's fuel for change. In partnership with the Rolex Perpetual Planet Initiative, this is Planet Visionaries. Listen or watch wherever you get your podcasts.

• 3:19Speaker 02

  All right, Regina and Scott, we've got a lot to get into.

• 3:22Speaker 03

  Let's, let's start with the insects. We've established there are a lot of insects. And I guess like, I'm wondering, how do you even go about counting them?

• 3:30Speaker 02

  So this study starts in a protected area in Costa Rica, and it looks at a very specific subset of insects called parasitoid wasps.

• 3:38Speaker 05

  And they're really diverse. There are these like tiny wasps, like really, really tiny.

• 3:43Regina Barber?

  Like millimeters tiny, says Melissa Guzman, an entomologist at Cornell University.

• 3:48Speaker 02

  And these itty-bitty wasps are called parasitoids because they lay their eggs in or on other species, like caterpillars.

• 3:56Speaker 03

  Can I say something? I saw a wasp do this to a cicada in my backyard, and it was horrifying. It was like alien in real life.

• 4:03Regina Barber?

  Oh, my gosh.

• 4:04Speaker 03

  It was, it blew my mind.

• 4:05Speaker 02

  Life finds a way.

• 4:07Regina Barber?

  But don't worry, these are not hatching out of human chests.

• 4:09Speaker 03

  Good.

• 4:09Regina Barber?

  It's gonna be okay.

• 4:10Speaker 03

  Okay, okay.

• 4:11Speaker 02

  Yeah, yeah, for now. But because these wasps are so small, it's like really hard to tell one species from another. So the scientists looked at a specific sequence of DNA from these wasps, and using that and some fancy modeling, they estimated there are 3,400 different species of one subfamily of parasitoid wasps in this one nature reserve.

• 4:32Speaker 03

  What?

• 4:33Speaker 02

  A lot.

• 4:34Regina Barber?

  Yes, a lot. But scientists wanted to take it a step further to get a sense of how many types of all insects there were in the reserve in Costa Rica, so they used that modeling and a larger sample of insects to get a number.

• 4:45Speaker 02

  And then they used that number to try to solve this big scientific mystery, Scott.

• 4:49Speaker 03

  I love myself a good big scientific mystery. Which one was this?

• 4:52Regina Barber?

  So scientists wanted to know how many species of insects existed on the entire planet. And the best estimate to this point, based on studies of beetles, is that there are roughly 6 million.

• 5:03Speaker 02

  And for perspective, Scott, even the most generous estimates of how many bird species there are on the planet suggest only about 20,000.

• 5:10Speaker 03

  Okay, so it's more than 6 million, I'm assuming, is where this is heading.

• 5:13Speaker 02

  Yes. So this new study, published in the Proceedings of the National Academy of Sciences, suggests that that 6 million number, you were right, Scott, is a huge undercount.

• 5:23Speaker 03

  How many insect species are there on Earth?

• 5:26Regina Barber?

  Yeah, between 14 and 20 million, at minimum. So up to three times as many species as previously believed. Here's Melissa again.

• 5:34Speaker 05

  There's so much that we don't know, right? And I think it's humbling, just to get a sense of how much we have yet to discover.

• 5:42Speaker 03

  That's wild. Like, but what do you do next? Do you have like an insect census? How do you, how do you try and verify this in any way?

• 5:48Speaker 02

  I mean, yes, there's like a lot of uncertainty with this kind of modeling. And, you know, we've only taxonomically described about 1 million insects so far. So, you know, do the math. It would take a lot, a lot, a lot of work.

• 6:01Speaker 03

  Okay. Next topic. Quasars. Fun word to say. Cool thing. Remind us what they are.

• 6:08Regina Barber?

  Yeah. So they are blazing bright centers of galaxies. And at the center of that is a supermassive black hole, millions of billions of times the mass of our sun. And dust and gas is spiraling into that black hole. It heats up and starts to glow. So when astronomers see these quasars, the light that they see is...

• 6:25Speaker 06

  A supermassive black hole caught in the act of feeding.

• 6:29Speaker 03

  What an amazing thing to think about.

• 6:30Regina Barber?

  Yeah. So that's Da Ming Yang. He's the first author of the study out this week in the Journal Astronomy and Astrophysics, which reports the discovery of 31 quasars. And these are among the oldest quasars ever found. And before this study, astronomers only knew a handful of quasars this old.

• 6:45Speaker 02

  Yeah. And Scott, something that's kind of cool about this is that these were all found with a space telescope that not a lot of people know exist. It's called Euclid. The European Space Agency launched it in 2023. And although it isn't as powerful as the Hubble Space Telescope or James Webb, it was designed to scan large swaths of the sky, which makes it really awesome at finding rare objects.

• 7:06Speaker 03

  I mean, this is a cool thing to think about and envision. But I assume astronomers need a little more than this is cool for doing this work. Like, what is the practical value of spending time trying to ID these?

• 7:18Regina Barber?

  Yeah. So these quasars are from like soon after the Big Bang. They're much bigger and brighter than astronomers would expect them to be that early in the universe. So Da Ming says there's a lot of questions about how they got so big, so fast.

• 7:31Speaker 06

  Like, what are they grown from? How did they grow? Like, these questions, by only collecting more of these quasars, we can answer this.

• 7:38Speaker 02

  And these ancient quasars might tell scientists more of the era when stars were born from the primordial hot goo that occurred after the Big Bang.

• 7:47Speaker 03

  We will save the primordial hot goo for another day.

• 7:51Regina Barber?

  Yes.

• 7:52Speaker 03

  And let's move on to topic three, wolves.

• 7:55Speaker 02

  Yes, an animal that is often controversial wherever it is cohabitating with people, you know, whether that's in the Western US where I am, the Midwest or Europe, you name it.

• 8:04Regina Barber?

  Yeah, and a new study out this week in the journal PLOS One is not going to soothe any of that hate some people feel about this predator.

• 8:10Speaker 03

  Hmm, why is that?

• 8:11Speaker 02

  So this study focuses specifically on wolves in California, which have migrated here from Oregon, and it looks at the impact they're having on cattle and, consequentially, people, ranchers.

• 8:22Regina Barber?

  Yeah, and researchers at UC Davis did a DNA analysis of the scat, you know, their poop, from two wolf packs in 2022 and 2023 to see what they were eating.

• 8:32Speaker 02

  In both years, Scott, they found that the primary food source for these packs was cattle.

• 8:37Speaker 03

  I mean, I guess my reaction, I'm not super surprised by that, right? Because that's the particular reason that ranchers have such stark feelings about wolves. Like, what am I missing?

• 8:46Regina Barber?

  That's reasonable to think, but it's uncommon for livestock to be the primary food for these wolves. So Tina Seitone, the study's lead author, says in most states, wolves predominantly eat wild game.

• 8:57Speaker 07

  But when wolves come to a human-dominated landscape like California with very little prey, you're going to see a very different composition of prey.

• 9:08Speaker 02

  So in other words, you know, California doesn't have big populations of elk like Montana or Wyoming. We don't have as many deer as there are in the Midwest or the Northwest.

• 9:17Speaker 03

  So the wolves just don't have a choice then? Is that it?

• 9:19Regina Barber?

  Yeah, that's right. So Neil Carter, who studies wolves at the University of Michigan, says this study, which he wasn't involved with, underscores how complicated it is for carnivores to come back to places that have fundamentally changed.

• 9:31Speaker 03

  If you want to have these animals on the landscape, you know, you have to start kind of building back the full ecosystem.

• 9:37Speaker 02

  Which in California would mean boosting mule deer populations, which are currently declining because of habitat loss, boosting other game species like elk that the wolves can eat. And, look, that's not something that could happen overnight, but I think this study does give the people that manage wildlife and want to see fewer conflicts between wolves and humans something to think about and to aim for.

• 9:57Regina Barber?

  Scott, I hope you enjoyed this, you know, not space segment, but, you know, news segment.

• 10:02Speaker 02

  And a little bit of space, a little bit of space.

• 10:04Speaker 03

  Just enough, just enough. I'll be back soon for spacing out, but in the meantime, always love being here.

• 10:09Regina Barber?

  Yeah, come back anytime.

• 10:10Speaker 02

  Yeah, thanks, Matt.

• 10:13Regina Barber?

  You can hear more of Scott Detrow on Consider This, NPR's afternoon podcast about what the news means for you.

• 10:19Speaker 02

  And for more science stories just like this one, follow Short Wave on whatever app you're listening to.

• 10:27Regina Barber?

  This episode was produced by Rachel Carlson and Jordan Marie Smith. It was edited by Rebecca Ramirez and Christopher Intagliata.

• 10:34Speaker 02

  Tyler Jones checked the facts. An Li Wong and Tiffany Vera Castro were the audio engineers. I'm Nate Rot.

• 10:41Regina Barber?

  And I'm Regina Barber. Thank you for listening to Short Wave, the science podcast from NPR.

• 10:58Speaker 04

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