Research Matters

Corrie Moreau on how studying ant microbiomes helps us understand ourselves - Research Matters S2E15

• Cornell University • Season 2 • Episode 15

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In this episode of Research Matters, Corrie Moreau, a leading evolutionary biologist and entomologist, explores the hidden world of insects, revealing how ants and their microbial partners can illuminate evolution, biodiversity and ecosystem health. The conversation spans cutting-edge genomic research, the discovery of vast new viral diversity, and the global importance of the Cornell University Insect Collection as a living archive of life on Earth. Watch here.

Corrie Moreau:

What we've been able to demonstrate through a series of both DNA sequencing and genomics, but also, you know, intentional manipulations, and experiments, ants that have a really tough cuticle or armor, that are herbivores, actually need their gut bacteria to provide them almost all of the precursor building blocks for them to build that tough cuticle.

Laura Reiley:

Wow. So it makes you wonder about our own microbiota, you know, is that is it analogous? Like, are there things that we get from it that that help us to, you know, be strong and thrive?

Corrie Moreau:

Absolutely, we do. And in fact, you know, some of my closest collaborators, actually work on human gut microbiomes. And the reason that they're so keen to work on ants is that we can do manipulations that we can't with humans. Right? I can't exactly take half of a room and say, "Y'all are all going to get antibiotics, and we're only going to give you sugar water for the next three months while you group, we're going to give fantastic food to. And then we'll see how your health is in the end."

Laura Reiley:

Welcome to Research Matters, the Cornell video podcast that explores how researchers are tackling real-world challenges and expanding our understanding of nature, society, and the world we live in. Today, we're joined by Professor Corrie Moreau, one of Cornell's leading evolutionary biologists and entomologists. Corrie is not only a scientist who studies some of the tiniest creatures on Earth — ants — and their microbial partners, but also leads one of the world's greatest scientific treasures, the Cornell University Insect Collection, home to more than 7 million specimens representing about 200,000 species. Welcome, Corrie.

Corrie Moreau:

Thank you. I'm happy to be here.

Laura Reiley:

Great. All right, well, so, let's start. Big picture about small picture. Why should people study ants or insects more broadly?

Corrie Moreau:

Yeah. So I think the fact that insects are one of the most important groups of organisms on the planet and most diverse, and the reason they're so important is they're sort of the thread that holds most ecosystems together. They're the food base for many larger things, like birds and reptiles and mammals, but they're also sort of the, the hidden architects of many habitats. So they're degrading, you know, decaying matter. They're turning the soil and making it healthier. They're bringing nutrition into the soil so that our plants can thrive and grow. And so they're sort of the the glue that keeps most of our ecosystems functioning.

Laura Reiley:

So how many discrete species are there? Do we know? Do we have a guess?

Corrie Moreau:

Well, we have guesses. So we'll start with just ants. And I say just because I shouldn't say just because I often get asked, why would you focus so narrowly on ants? But there are more species of ants than all the birds and mammals added together. And that's just ants.

Laura Reiley:

That's just ants?

Corrie Moreau:

And so that's about 15,000 described species. But we know when we look at the new species to science, the numbers at least double if not triple. Everywhere we go in the world we find new species. But then if we sort of back out even further and look at insects more generally, I mean, we're talking hundreds of thousands of species, that have names already in science, and there's so many new species out there waiting to be discovered.

Laura Reiley:

Are there new ones emerging? I mean, are there — are we on a daily basis or monthly basis finding more?

Corrie Moreau:

Absolutely. And in fact, just a few years ago, a colleague of mine named a new species of ant after me. It's Strumigenys —

Laura Reiley:

What an honor!

Corrie Moreau:

I know it's the hugest honor, but it's Strumigenys moreauviae. But then when we describe a new species, you have to designate a single specimen, a single individual, to represent the name for all of eternity. And those are called the type specimen. So after naming that species, he actually gave it to the Cornell University Insect Collection. So we're the holder of that brand new species. And we actually have thousands of type specimens right here at Cornell in the Cornell University Insect Collection. In fact, we have a special room just to protect them because they're one of our most cherished resources.

Laura Reiley:

How do you protect them? I mean, is it is it temperature controlled and light sensitive, kind of —

Corrie Moreau:

Absolutely. Temperature-controlled, light sensitive. We actually really want to make sure that other pest insects don't get in there, because they will eat them right up and so we have to do a lot of pest control and pest monitoring, as well.

Laura Reiley:

So in, in your studying ants, it seems like you do a lot of work studying even smaller than ants, the kind of... their microbes that are kind of symbiotically inside of them, working with them, kind of like our gut biome works for us. Why are you studying that and how are you studying it?

Corrie Moreau:

Yeah, that's a good question. So I have to tell you, when I started my career, I never thought I'd work on bacteria. I am totally an entomologist through and through. I love insects. Ants are my favorite, but —

Laura Reiley:

You were an E.O. Wilson student, right?

Corrie Moreau:

That's right. He was one of my PhD advisers.

Laura Reiley:

And he was an ant guy.

Corrie Moreau:

He's an ant guy. That's absolutely right. Yeah. And so as I began to try to figure out why there were so many species of ants and why they were found where they are, one of the things that I observed was that they had a very close relationship with plants, either living in and on them and in many cases switching their diet entirely to be herbivorous, eating only plant based diets. That led —

Laura Reiley:

Wait, are most ants herbivores? I'm, I guess I assumed that.

Corrie Moreau:

No. Most ants are predators.

Laura Reiley:

Oh!

Corrie Moreau:

I know, so they're out hunting prey on the forest floor or scavenging other dead insects. It's quite rare to switch entirely to herbivory, and in fact, across all of the ant species, we know it's happened at least 11 times independently. And so what I wanted to try

Laura Reiley:

Is this a scarcity thing or why...

Corrie Moreau:

I think it's, you mean why is it so rare? Or why do they switch?

Laura Reiley:

Why do they switch?

Corrie Moreau:

I think it's a competition thing. Right? You can only pack so many species into a habitat if you're all relying on the same resources. So if you all figure out somewhere new to live or something new to eat, you can suddenly pack more species into the same habitat. And I know that you recently visited the tropics. And if you go to the tropics, it's just teeming with ants.

Laura Reiley:

I was just amazed. The leafcutter ants, you know, we kind of saw this, like prancing row of leaves walking and, you know, kind of what is that? And our guides were saying these are the leafcutter ants and we kind of learned about their, society and all the different functions that, you know, kind of... so do you when you're describing an ant species like that, is it kind of like a macro-organism? Is it kind of like the show Pluribus?

Corrie Moreau:

Yeah. And so in fact, what we consider, ant colonies and other social insect colonies, we call them super organisms, because really, there's only one or maybe a few individuals that are involved in reproduction, like our reproductive organs. And all the rest are out there to bring resources and keep the colony healthy. And so we tend to think of those as like the cells of the rest of our body. And so, you know, if you think about an ant colony, if you see a few individuals out foraging and they are to be eaten by predators, the colony will still thrive and be happy. It's sort of like just losing a fingernail. But mostly if the queen dies, then suddenly you will have the colony die through time, through attrition, because they can't replace themselves. So they're essentially this functioning super organism.

Laura Reiley:

So talk a little bit about how does a queen get elected or created or deigned or whatever, you know?

Corrie Moreau:

Yeah, that's a great question.

Laura Reiley:

Coronated, I guess would be —

Corrie Moreau:

Yes. So an ant colony is, you know, most of the individuals you see foraging out in the environment or fighting battles or gathering food, those are what are called workers, and they're actually sterile and cannot reproduce. And their sole job is to sort of help keep the colony functioning. But about once a year and a new reproductives are formed, and those are both males and females. And so when the environmental conditions are right, they're pushed out into the environment so that all the other colonies are releasing their sexual reproductives at the same time so that you have less probability of meeting with your brother. So then they mate, and then almost right away, the males die. So a male's sole job is to —

Laura Reiley:

Let that be a lesson to you, gentlemen.

Corrie Moreau:

And then the queen, she continues to fly around and find a suitable place to start a new colony. Once she lands on the ground or, if she's a canopy-dwelling species, on a tree that she thinks is the right place to start her new nest, she'll reach back and pull off her wings, and she'll actually have little wing scars, and then she'll dig into the ground, or dig into the tree and start a whole new colony of workers. And I think one thing that's important to remind everyone listening is that almost every ant you've ever seen in your life is female. So females are the ones that do all the jobs in the colony. They're the ones that are gathering food and building the nests and caring for the young and fighting the battles to the death. Those are all females. Males are really only produced, one time of year. And that's solely for reproduction.

Laura Reiley:

That is incredible. So is there an optimal hive size or kind of community size for ants? And is it does it vary by the type of ant?

Corrie Moreau:

Absolutely. And in fact, it's really species-specific. So some species like the Dracula ants I worked on early in my career. Their entire colony can be ten individuals. Where then things like —

Laura Reiley:

Where do they live?

Corrie Moreau:

Oh, they live all over the world.

Laura Reiley:

OK.

Corrie Moreau:

And then army ants, actually, you know, you can have hundreds of thousands of individuals or even the leaf cutters, right? And so it's very species-specific and they're always going to try to grow to their optimal size as far as what the colony can sustain based on their biology and the resources they can bring in and the number of eggs that the queen can lay.

Laura Reiley:

Are the consequences if a community gets too big? I mean, are there... can they have a some kind of cataclysm, a die off or, or something like that if they...

Corrie Moreau:

Absolutely. And I think the place that we sometimes see it is in areas where we have introduced species who that come in. Right, because they often don't have natural predators or they don't have natural viruses or pathogens. And so they'll start to grow and grow and grow. And then eventually they're either running out of resources or then once a new pathogen invades, because they often don't have much genetic diversity, the entire population can crash.

Laura Reiley:

OK. So, going back to talking about their...the kind of their the benevolent or the symbiotic microbiota...

Corrie Moreau:

Yeah.

Laura Reiley:

...part of what you study, how do you study that? What are the tools that you use to study?

Corrie Moreau:

Yeah. So, fundamentally, first and foremost, I sit at a microscope dissecting out ant guts using watchmaker forceps. So it's a lot of very tedious small work. And the reason we want to do that is because the digestive tract of ants is like us. It's not homogenous across. And so we want to look at what are the bacteria associated with each of those compartments of the gut, because they might either have no role or they might have an important functional role. We won't be able to tease that apart unless we dissect them out. Then we use a bunch of molecular and genomic tools to study them so that we can identify the both what the bacteria are, how diverse are the communities, but also what are the functional roles, what genes are available within the genome of the bacterium that's their symbiont? Could they be benefiting the host or are they a pathogen of the host? We can start to get hints of that.

Laura Reiley:

I don't want to interrupt too much, but what is a symbiont...

Corrie Moreau:

Yeah... Yeah. Symbiont is just one species that's often associated with another species.

Laura Reiley:

Okay, but not parasitic. Not —

Corrie Moreau:

It can be parasitic or it can be beneficial. So, you know, it depends on whether you want to think of them as pathogens or mutualists. And so mutualists are typically thought to be always beneficial. Commensals are in the middle. They seem to have no cost on the host. And then of course the parasitic species are, are often detrimental to their host.

Laura Reiley:

OK. So I think that you were involved in the work that, that determined that ants are older than we thought, like 140 million years ago. They were...they began.

Corrie Moreau:

Yeah.

Laura Reiley:

Versus I think we thought it was 100 million... So what were the... how did you determine that and what were the tools that you utilized to get there?

Corrie Moreau:

So just like we can create a tree of life for us, like our families, we can do the same thing for any group of organisms on the planet. So what we use is DNA. Just like if you send off your samples to Ancestry or 23andMe, we do the same thing but for ants. So what we're trying to figure out who's related to who. And in doing so, then we can even use the fossil record to get an idea of when did particular lineages arise. So the fossil record for ants is very rich and very deep. Some of the earliest fossils are about 10 million, 15 million years old. The oldest fossils are around 100 million years old. And these are ones that we can confidently assign to the ants.

Laura Reiley:

These aren't like proto-ants or some kind of —

Corrie Moreau:

Some are quite proto-ants. Some look exactly like ants look now. It's pretty remarkable. And so then once we have the sort of tree of life for ants, then we can use that fossil record to help us calibrate timing on that. And so we knew that the oldest fossil was of, you know, a modern lineage is 100 million years old. So we knew ants were at least that old, but we didn't really know how far back in time. So we can use a series of analytical and statistical models to help us understand and stretch that back in time. And that allowed us to say ants are, in fact, about 140 million years old, with a lot of confidence because we were able to use so many fossils across the tree of life for ants.

Laura Reiley:

So is...are they related? I think I read that they were somehow related to the beginning of flowering plants.

Corrie Moreau:

That's right.

Laura Reiley:

What is the connection there? Because I don't think of ants as pollinators or as being reliant upon flowering plants.

Corrie Moreau:

That's absolutely right. And so, you know, you're exactly on the right path. So for many things that are pollinating flowering plants, of course, we saw them go through a burst in diversity as soon as the flowering plants came on the scene, right? They were running around and using the plants, eating the plants. Well, the same thing turns out to be true for ants. So as I mentioned before, most ants are predatory. Well, the earliest ants were in fact predators. They were living in the ground, they were nesting in the ground, and they were eating other arthropods, mostly other insects and spiders. But as the flowering plants expanded across the globe, all those pollinators started diversifying. So did all the herbivores that were feeding on them. So the ants were starting to take advantage of all these new prey items. So it wasn't a direct connection —

Laura Reiley:

It was a food source coming to them, flying over to them or something.

Corrie Moreau:

That's right. But then they also began to live entirely in the canopy and then eventually start to have plant-based only diet, some species.

Laura Reiley:

So can you talk a little bit about the concept of biogeography? I don't think that's a term that most laypeople know. And how does that, how do you study species that, well, explain what that is.

Corrie Moreau:

Yeah. So biogeography is just, you know, so we look at where are the contemporary species that are alive on the planet today are distributed and then we ask the question, how do we think they spread through time? So I know many of us in our geology classes or in our, you know, world history classes, learned that at one point, all of the continents were connected, right? And one big supercontinent called Pangea. Yeah, yeah. Then it split into two, right? And we had Laurasia and Gondwana. Well, then that further began to split. So what we try to understand is that the species that are on the planet now, were they connected at one point based on where those tectonic plates were? And does that line up with how old those lineages are? So to give you an example, we have a lineage of ants that's very diverse in South America and very diverse in Australia. They look a lot alike. They behave a lot alike. And then through using the DNA and the tree of life, we were able to show that they're very closely related to each other. And the split of when those two, you know, groups became separated actually lines up with when South America and Africa began to split. So we can actually time...line those things up. So that's what biogeography is — sort of using what we know about geology, along with what we know about the diversity of organisms on the planet and trying to reconcile those.

Laura Reiley:

That is incredible. Tell us a little bit about the insect collection and how, how you gather specimens. And is there, is there a citizen science component to it? And, you know, kind of what, what are the objectives of the collection?

Corrie Moreau:

Yeah. So the Cornell University Insect Collection, as you mentioned, has 7 million specimens. It's the oldest entomology collection in the United States. It's been around since almost the founding of Cornell itself. In fact, the original collection was actually in...the original curator was a chimes master. So it used to be a McGraw Hall.

Laura Reiley:

That is a, that is a very interesting set of hobbies.

Corrie Moreau:

Yes. Yeah. Exactly, exactly. And so, so we've been accumulating specimens since then because we've been, we're the oldest entomology departments in the United States. And so we've been teaching students how to study insect diversity since almost the founding of Cornell. And so our collection is there really for science, scientific research. But of course, also education. So many students actually work in our collections. Many entomologists around the world got their start right here in our collection. But we also have specimens that we designate to the teaching collection. And those are for all the classes where we want students to get hands-on experience working with specimens. But even then across Cornell, we have all these different classes who want to come in and spend time in the collection to use them as a resource for learning, whether it's through an art lens, whether it's through a literature lens. Because we have a huge collection of, Vladimir Nabokov's butterflies. You know the novelist actually was a professor here at Cornell, but also Lepidoptera collected butterflies. But the main reason we have the collections is for scientific research.

Laura Reiley:

So is...in the digital age. Are there tools now that help disseminate or help share information across institutions?

Corrie Moreau:

Absolutely. And so one of the biggest efforts is around what we call digitization. And so that's both transcribing the information that's on each and every one of those insect labels, but also taking high resolution photographs so we can share those. So we actually have, since I arrived, we've already digitized about 125,000 insect specimens.

Laura Reiley:

Is this kind of a manual thing by thing, a human doing —

Corrie Moreau:

Yeah. Unfortunately —

Laura Reiley:

A labor of love.

Corrie Moreau:

But because we want people to know what we have in our collection, because, you know, when experts from, you know, all over the world know we have, they're more likely to either be able to visit or in many cases, you can... If you're a well-established researcher, you can check out or borrow our material. We're essentially a lending library of biodiversity.

Laura Reiley:

Wow. Incredible. All right, so speaking of biodiversity, so obviously a lot... a lot is made of species decline. In terms of, like, a harbinger of doom in terms of climate change. What are we seeing with insect species and is it something...is it trackable? And where are we seeing the greatest declines?

Corrie Moreau:

Yeah. Unfortunately we are seeing insect declines. And it seems to be happening across the globe. Nowhere seems untouched by this. One of the things that has been the biggest tool for us being able to measure that is actually collections, because they actually give us the ability to ask what was there before, and we can compare it to what's there now. So we published a paper a few years ago where we sampled all of the ants across the state of Florida through time, because two people in the past had done some historic, very thoughtful collecting that we could replicate. And so we said, well, how is it changing through time? And what we were able to show is that most of the species that were native to that part of the world are disappearing, and lots of introduced species are coming on the scene.

Laura Reiley:

Is that because of the transience of humans and, and — Invasives are showing up on the bottom of a shoe or a boat or whatever.

Corrie Moreau:

It's definitely the transience of humans. But it's also because as we modify our habitats, the native species, we're, you know, we're making the plants that they rely on no longer available. We're making cities way too hot for many species that are not, you know, had not evolved in that kind of habitat. And so, unfortunately, through just our actions, whether intentional or not, we are, you know, transforming the globe. And that's having huge impacts on biodiversity and on species that were once, you know, important components of ecosystems and are now disappearing quite rapidly.

Laura Reiley:

So is that kind of contributing to pest pressures in an agricultural sense? I mean, do you do any work on that kind of thing?

Corrie Moreau:

I don't work on it directly, but I collaborate with a lot of people who think very deeply about this. And, of course, you know, as we modify the habitat, we're going to change what species can thrive there. There's actually a lot of really great work trying to figure out how to recruit beneficial insects into these habitats by creating some of these, like hedges and rows near agricultural plots. So we essentially are providing habitat that's good for the native species so they can help control the pest species. And many times the, the crops that we grow are not native to this region. So the pests that come along are usually not native to these regions. So trying to identify where they're originally from, what are the ways that we can control them hopefully without always having to use pesticides. But sometimes we will have to use pesticides in order to grow our food.

Laura Reiley:

So, we're, we're running out of time, but I have a bunch of other questions to ask. So, I know that you've done a lot of work, as associate dean, you did a lot of work on kind of diversity in the sciences and especially in in your field.

Corrie Moreau:

Yeah.

Laura Reiley:

For young people interested in, in entomology or just kind of the sciences, do you have any guidance on, on how to, how to dive in?

Corrie Moreau:

Yeah, I would say figure out what you're passionate about. And then find someone who can serve as either a formal or an informal mentor to you. And also role models. I think we forget that, sure, having someone who's there to give you hands-on opportunities, but also think of who you want to strive to and try to think about what were the steps. You know, and it's difficult because sometimes you look at them now and they're so successful, but try to see if you can figure out where they were, what were they doing when they're at your career stage, and then what were the steps they took to be successful. I think —

Laura Reiley:

Did you have a role model? Did you have a kind of an early someone who sparked your interest?

Corrie Moreau:

Oh, absolutely. And for me, I was really fortunate because the one of those people I got to be my PhD advisers. Right? Which was E.O. Wilson, who was one of the, like one of the most famous ant biologists in the world.

Laura Reiley:

I think I sat in on a class of his at Harvard one time. Yeah. Yeah. Incredible.

Corrie Moreau:

Yeah. He was a phenomenal mentor. But I also think we have to think about role models. And for me, earlier in my career, I didn't have a lot of women role models. There were not a lot of people of color role models. And so I really took an opportunity during grad school to try to seek out people who would help me understand the natural world, but also how to navigate, you know, science more generally in academia, while trying to be inclusive and welcoming to everyone. So I think all of us, the goal for us is really to to help, you know, train the next generation of outstanding scholars, whether they're in science or not. And so we really want to make sure that we're doing the work here at Cornell and broader in the community to to be able to give those opportunities to anyone.

Laura Reiley:

How about for just avocationally interested, people who like bugs, kids who like bugs or, you know, what are what are some either tools or resources that, that you recommend.

Corrie Moreau:

Yeah. I highly recommend iNaturalist. And so, you know, it's just an online app where you can, you know, record whatever diversity you see. And I know that might sound like, well, why would I do that? But what's really brilliant about iNaturalist is that there are lots of scientists on there validating the species. And then once —

Laura Reiley:

Do you get feedback as a, as a...

Corrie Moreau:

You sometimes do, yeah. And then what's great about it is we as scientists use data from iNaturalist all the time, because once it's been scientifically validated, we can use it like data we're generating ourselves. So as we're trying to track, where is a species originally from, when did it first show up? How quickly is it spreading across. We can actually use iNaturalist data for that. So we need people out snapping those photos and any and everything they see. It's also a great way to make an online community of other people interested in the group of organisms you're working on. But I would say also —

Laura Reiley:

So it has sub-areas. So you're interested in ants, for instance. It'll have its own community of iNaturalist folks.

Corrie Moreau:

Yeah, absolutely. And I would say also try to find ways to either connect with a local natural history museum or at a university campus. But, there's often these things called BioBlitzes is where people go out and for 24 hour period of day, we'll record every organism they can find in a particular location. So we often partner with the Museum of the Earth right here in Ithaca.

Laura Reiley:

And this is a collaborative thing that you kind of report back?

Corrie Moreau:

That's right. And so we record all the organisms we can find. There's somebody out there doing plants, mammals, birds, fish. You know, we do insects, plants, right. So just trying to see and then we can actually map it every single year. And see what's changing, what's new popping up. And it's just a great way to get to know your local flora and fauna.

Laura Reiley:

That's fascinating. How do you find out about that? It's a it's a particular day in, in Ithaca that this happens.

Corrie Moreau:

Yeah. So I think it's I would say check out the Museum of the Earth's website for the ones here in Ithaca. But they're happening all over the world. They're, it's just phenomenal. And I would say, you know, if you really want to get excited about insects and you're here in Ithaca, be sure every year to come to Insectapalooza.

Laura Reiley:

Yeah, I've heard nothing but good things. I haven't been yet myself.

Corrie Moreau:

Oh my gosh, it's amazing. We have 3 to 5,000 people come for one day to Stocking Hall. We have all the research labs are sharing their work.

Laura Reiley:

Is there a petting zoo? Is there, like hands-on stuff?

Corrie Moreau:

There is an insect petting zoo. But we also bring out hundreds of specimens from the Cornell University Insect Collection. So you can just see the diversity of what insects look like. There's seminars or lectures to go to. It's just a fantastic time for people of all ages, not just children.

Laura Reiley:

That's great. All right. Well, thank you so much to Corrie Moreau for coming, for sharing her insights. Research Matters is produced by Cornell University, where curiosity meets impact one question at a time. If you enjoyed this episode, share it with someone who loves nature, science, or just discovering something new. Thanks for watching and we'll see you next time.