Science Friday - Climate And Farming, Mars 2020, Fireflies. August 23, 2019, Part 2

Episode Date: August 23, 2019

From cutting back on fossil fuels to planting a million trees, people and policymakers around the world are looking for more ways to curb climate change. Another solution to add to the list is changing how we use land. The United Nations’ Intergovernmental Panel on Climate Change, or IPCC, released a special report this month that emphasized the importance of proper land management, such as protecting forests like the Amazon from being converted to farmland, has on mitigating climate change. Robinson Meyer, a staff writer at The Atlantic, joins Ira to discuss the ins and outs of the report. Cynthia Rosenzwieg, a senior research scientist at NASA Goddard Institute for Space Studies and one of the lead authors, also joins to talk about ways we can use land to reduce the amount of greenhouse gas in the atmosphere. Plus: NASA’s Mars 2020 mission is just around the corner. Next fall, the Mars rover will launch with an upgraded suite of instruments to study the red planet in a way Curiosity and Opportunity never could. When it lands on Mars, it will search for and try to identify signs of ancient life. But how will it know what to look for? Katie Slack Morgan, deputy project scientist on the Mars 2020 mission, and Mitch Schulte, a Mars 2020 Program Scientist, talk to Ira about the chances of finding evidence for ancient life on Mars—and why the Australian Outback might be a good testing ground. And if you take a walk at night during the summertime, you might catch a glimpse of fireflies lighting up the sky. But scientists are learning that these bioluminescent insect populations are vulnerable to habitat loss, pesticides, and light pollution. Biologist Sara Lewis talks about conservation efforts including Firefly Watch, a citizen science project that maps out firefly populations around the country. She joins geneticist Sarah Lower to discuss how individual species of fireflies create different blink patterns, as well as the difference between fireflies, lightning bugs, and glow worms. Subscribe to this podcast. Plus, to stay updated on all things science, sign up for Science Friday's newsletters.

This is Science Friday. I'm Ira Flato. Later in the hour, we'll be discussing how land and soil can be used to both hurt or help the environment. First, NASA's Mars 2020 mission is now just around the corner. Next fall, the next Mars rover is scheduled to launch with an upgraded suite of instruments to study the red planet in a way that curiosity and opportunity never could. Now, one of its main objectives when it gets to the Martian surface will be to search. for and identify signs of ancient life on the red planet. But how will it know what to look for? Well, one sign of Martian life could look pretty familiar. Evidence of ancient stromatolites.

Those are one of the earliest life forms ever discovered on Earth. Stromatolite fossils are found today only in a few areas around the world, including the remote outback of Western Australia. That's where NASA scientists headed this week to study them, hoping to gather clues about whether this organism could have also lived on ancient Mars. Here to tell us more about what they are looking for this week. Coming to you all the way from Pilbara Region of Australia is my guest, Mike Schulte, Mars 2020 Programmed Scientists. Welcome to Science Friday.

Good morning. Good morning to you. Thank you for joining us. Also, joining me from JPL headquarters in Pasadena, California, is Katie. Stack Morgan, Deputy Project Scientist for the Mars 2020 mission. Welcome, Katie. Thank you. Robin, let me, Mitch, let me ask you first. You're with a group of NASA and European scientists down in Australia, right? Why is Australia such a great place to go looking for them? So, Australia is a great place to look for these because it contains, in the rock record, some of the most ancient evidence for

life on earth. These rocks here in Western Australia are three and a half billion years old, and they contain these stromatolites, these microfossils that we see in the rock record. And this is one of the very few places in the world that has this old rock record that contains these traces of ancient life. So are you sort of like taking photos of them so that when the rover sends back a photo, you might be able to compare them, for example? Well, so morphology is only one clue that we use to determine whether something is evidence of life and a rock record. In this particular case, one of the big clues, though, is how they visually look. A lot of times people see these in two dimensions, and they're not convinced by the biogenicity of these things.

And so really getting out into the field to see them in three dimensions to study the rocks and what the rocks tell us about the environments is also very key to really, helping us decide that these are evidence of life. So what are the conditions on Mars in which a Martian stromatolite would have grown? Same as Earth? Well, we think so. There are a variety of environments here on Earth where we see stromatolites forming today and where we see in the rock record, again, the environments being told from the story of the rocks.

And so we think that similar kinds of conditions would have existed on Mars. So, for example, we see stromatolites forming today in hot spring environments, and we see evidence on the surface of Mars that there may have been hot springs in its ancient past. We also see a lot of stromatolites forming in lacustrin or very shallow marine kinds of environments, and we interpret those from the rock record for these ancient rocks. And we think, especially where Mars 2020 is going to land, that there was an ancient lake environment where the rover will be landing. That is cool. Katie, the 2020, Mars 2020 mission is designed also to look for a few different signatures of life, not just Trometalites, right?

That's right. So Mars 2020 is headed to a place called Jezzaro Crater. It's an ancient crater on Mars. And what's really exciting about the comparison between Jezero, the rocks in Jezero and the Rocks in Australia, is that we're talking about the rocks of about the same age or even older on Mars. And so the kind of life that we're seeing in the rocks preserved in Australia may very well be similar to the rocks. the type of sign of life that we could expect to find in Jezero Crater on Mars with 2020. Well, let's talk about, we've had rovers on Mars for a long, long time now. How is this mission different from all the other rovers, Katie? Yeah, so Mitch talked a little bit about how the shape of the rocks and the shape of the stromatolites is only one way you can identify a potential biosignature.

The Mars 2020 rover has, as part of its instrument payload, a series of instruments that can not only take images of the rocks, but also map out their composition and whether they have organics in them. And that's really exciting in terms of building a case for a biosignature. It's not just what you see, but also what the rocks are made of and whether they have organics. Any way, okay, let's say you find strometalites, any way to get them back to Earth? You've now found some valuable information, right? Yeah, well, Mars 2020 is the first mission in a potential series of mission whose objectives is to bring Mars samples back to Earth. And so our job with Mars 2020 is to find the best possible samples

we can in Jezero Crater and cash them and collect them on the surface for a possible future mission to go pick them up. And so are you saying that you can identify, positively identify as Dromatolite with the equipment that you have on the rover? You know, we can make a really good case for one, but we're not going to be able to positively identify the signs of life likely until we get those samples home if we get them home. Mitch, how are we going to know how old the Martian stromatolite fossils are if you find them? Well, there are a variety of ways of doing that. One of the things that we see here in Australia is that there are different kinds of rocks in which these microfossils are encased,

and there are minerals in those that can be radiometrically dated. The other way that we can do that is look at layers above and below where the microfossils exist, and we can often date those kinds of. of minerals as well. So on Mars, what we'll try to do is collect some rocks that contain these kinds of minerals that we can radiometrically date so we can actually try and pin down the date of those microfossils if they exist. Katie, what about the recent detection of methane on Mars? Does that make you feel like you might find stromatolites or any forms of other kinds of former life?

Well, the methane detection by the Curiosity rover and Gale Crater is very exciting from an astrobiological perspective. We don't quite know exactly why we're seeing that signal on the timescales that we are in Gale, but I think it does increase our excitement about the chances of finding life and for us on Mars 2020, ancient life on the surface of Mars. Is it basically thought among scientists, geologists who now work on Mars that it's a given that might, you know, might have been life on Mars one time or another, given that all the water and the evidence of water, there has been, Mitch? Yeah, so that's really one of the reasons that we are excited about Mars

is because we do see this evidence on Mars's surface that there was water in Mars's past. And knowing that Mars and Earth are sort of similar geologically, some of the kinds of environments that we think existed on Mars long ago are the kinds of environments that we see this evidence preserved here on Earth. So it is very exciting, and the possibility we think is there that life could have started on Mars as well. How far is this rover going to rove around? How many days? What is the length? Is this a three-hour tour? I mean, what are we talking about here?

Also, the prime mission is currently for one Mars year, which is about two Earth years. And it has the capability to traverse about 20 kilometers. We've seen from our previous rovers that they're capable of doing better than that. but the mission design is for 20 kilometers. So that gives us a lot of range to be able to do that. And having the mission be for one Mars year gives us a lot of time. And are you putting the rover down in a spot that you think is most likely to find evidence of life? Yeah, that's the idea.

And so in selecting the landing site was a process that involved the entire science community. So we had a series of workshops to define what would be the best place to send the rover. And so through this series of workshops and then making the decision at NASA headquarters, we've chosen Jezero crater, partly because we see evidence of a river coming into what was once a lake that filled this crater that Katie talked about. And so we see various types of minerals from orbital data that also indicate that there were environments that would have been conducive to hosting life, at least. How did it go out on the field there, Mitch, this week in Australia? It was really great. So as you mentioned, we had both the Mars 2020 and the Xomars 2020 rover teams here.

And there was a lot of great collaboration and great cross-talk. And I think it really opened people's eyes to see these rocks firsthand. Because you read about these, you know, if you're a geologist like I am, this is one of those bucketless places you have to go to see some of the oldest evidence of life on Earth. And I think the scientists were really excited to come here and see these rocks, themselves. So it's been a really great week. So you have a bunch, Katie, are there a cavalcade of instruments on board this rover? I mean, what kinds of instruments will it have?

Yes, there are. We have a bunch of new instruments and some updated instruments from the Curiosity Rover. So we have improved cameras. We have some geochemistry instruments, as well as the mapping instruments I talked about. We also have the ability to see into the subsurface with our radar instrument. And we have a technology demonstration. to produce oxygen from CO2 in the Martian atmosphere. Let me back that up again. You're going to make oxygen out of the CO2. That's right.

Is that a demonstration of possibly, you know, inhabitation and making your own oxygen? Well, it's a technology demonstration thinking about the future of humans to Mars, so preparing for that. So, of course, if we were to send humans to Mars, we would need oxygen both to breathe, but also particularly for the fuel to get those astronauts home. And so we're demonstrating that technology,

on the surface of Mars with this mission and are excited to see us do that on the surface of Mars. What kind of fuel would you make out of the CO2? So it would be oxygen, oxygen-based fuel. Such as hydrazine or something? I'm just guessing. I think that's a pretty good guess. Mitch, do you have any thoughts about that? Yeah, so the oxygen, of course, in order to burn things, you need an oxidant.

and so oxygen is a really powerful oxidant. So we would combine the oxygen with some other fuel source such as, and so for the rockets that go to Mars, they typically burn either liquid hydrogen or kerosene. That's the reduced form of the fuel, and then you need an oxidant to burn it. So in order to get the people off the surface, you'd have to have some reduced form of fuel, but making the oxygen would be a really great step to be able to get them off the ground. All right. We're going to watch this very closely, and thank you for giving us a heads up on this mission.

Mitch Schulte, Mars 2020 program scientists with NASA, Katie Stack-Morgan, Deputy Project scientists for the Mars 2020 mission. Thank you both for taking time to be with us today. We're going to take a break, and we come back. You're welcome. We're going to talk about using land and making a climate change, you know, maybe from worse to better. There's a way to turn around climate change. We're using the soil. We're going to talk about it after this break.

Stay with us. This is Science Friday. I'm Ira Plato. From cutting back on fossil fuels to planting a million trees, people and policymakers around the world, are looking for more ways to curb climate change. Well, another solution to add to the list, how we use land. The UN Intergovernmental Panel on Climate Change, the famous IPCC, released a special report this month that looks at the impact land management has on climate change. change. And here to tell us about the report is Cynthia Rosenzweig, a senior research scientist at NASA Goddard for space studies and one of the lead authors of the report. Thank you for joining us today. Thank you, Ira. Give me a few of the main takeaways from the report. For the report overall, the main takeaway is that climate and land are strongly connected and that land has an enormous role to play in solutions to climate change. both how we can recover from, you know, from what we've done and also exacerbating it?

Give me an idea. Sure. Well, first of all, let's just realize, so the land is 30% of the global surface area, but the seven and a half million people like us, like you and me, live on the land. Billion people. Billion, billion, billion. Seven and a half billion people. and projected to go up to almost 11 billion by the end of the century.

And so we are all strongly connected to the land. So that's why I think this report has really a strong message for not only the policymakers, of course, but for everybody who's so connected to the land. For example, over 80% of the food that we eat comes from land-based sources. Give me an idea of how the land interacts with the climate. What is going on in this soil, for instance? Yes, so the soil is an enormous repository of carbon, and one of the main ways that we can help to solve climate change,

the land can't do it all. There's a lot of things that we have to do with fossil fuels as well. But the land can be used as a sink for soil carbon. that's called soil carbon sequestration. I mean soaking up the CO2. Soaking up CO2 from the atmosphere, excess CO2 from the atmosphere. It can also be used to grow bioenergy, which we need to substitute for fossil fuel. But we have to be careful that we don't run into a competitive situation between food production and solving climate change.

So one of the things that the authors of the report worked on a lot is looking at, how we can do both with the land. Yeah. Grow enough, grow bioenergy, but at the same time, grow enough food. So we make sure that we are able to feed those nearly, you know, 10-something billion people in 2100. Our number 8447-248255, our phone number again, 847-248255. You can also tweet us at SciFri. One of the issues that the report addresses is converting more.

and more forest land into farmland. And we're seeing that in the Amazon rainforest. We were just talking about that. Tens of thousands of fires have been started this year to burn out the forest for agriculture. That must be an incredible hit to the environment. Yes, it is because when those fires are started and burn, they burn up. When they are on the old growth forest in particular, then there's an enormous hit of carbon into the atmosphere. And then it takes really a long time to get that back.

So that is a major source of greenhouse gas emissions. But we also, by the way, there's also air quality and health effects, of course, from the smoke as well that we're seeing in the news very much. in the news today. So what the report is really saying is that these different land uses, the importance of the natural ecosystem, such as the Amazon rainforest, as well as food production, that can coexist, but we need to wisely manage them, and we have to start doing that soon. and we're going to need to scale up those solutions rapidly. But that means you're going to need international cooperation, right?

Right. Well, isn't that a challenge? Well, certainly the intergovernmental panel on climate change is a body organized by the United Nations. And so this report is approved, the summary. for policymakers, which I just got back from Geneva, from the approval session with the delegates from the countries. And the scientists and the delegates of the countries work together to bring forward together these key knowledge that can be used to find the solutions.

Well, if all these countries, you know, the history is full of wars and things that are fought over oil or treasure or riches and people. saying, you know, if you do this, we don't get enough of that. Why is there not more international pressure on Brazil, for example, these fires, they're going to affect the rest of the world's life. They're the lungs of the earth. Why are we not seeing more pressure from all the countries that are going to have to live on the planet from years on to stop these fires?

I mean, you know, is this diplomatic nicety that, you know, no one wants to take on? Well, Ira, I'm a scientist. And what our role is to really provide the knowledge that is needed so that all the countries can make their own decisions. That's really how the Paris Agreement for climate change is really organized, that the commitments are nationally determined. And there's, you know, many, many years of ongoing discussion to actually find solutions for the climate change challenges. And the report offers so many of them. Give me a few examples of what some of those are. Sure, absolutely.

So I'm going to talk about the food part because I was the – Foods, we're all going to have to eat. We're all going to have to eat, and we all do eat, and that's why we all have a role to play. The report takes a food system approach. So it doesn't just only look at the farmers now and the production side. Of course, there's important things that the production side needs to do to both reduce greenhouse gases by, for example, developing patty rice systems that don't produce as much methane. But this food system approach then allows us to look at the supply chains. Okay, from the field to the fork, there's a lot of transportation, there's a lot of energy use for storage, for grain drying.

These are some very high, some of these are very high energy and high fossil fuel using processes. And so we need to look and see how with the supply chain as well. But the part then also that now this food system approach really enables us to do is look at the consumption side as well. What about people's two things. D diets and also food, loss, and waste. These are two areas that many people have choices about. Not everybody in the world has choices about the food we eat, and we have to be very careful that we're not making any blanket statement for everybody. But for those who have food choices, the report brings forward that some diets, in particular, those rich in red meat, have higher greenhouse gas emissions than more diets, plant-based diets.

Yeah, because they use also a lot of water as a resource, which is going to be getting scarce. Yes, exactly. And so focusing on diets that reduce land use and that have efficient water use, as well as lower greenhouse gases, this is really an important area that the report brings forward. You talked about the soil being a sink, and it's a technical term for like a sponge. You know, you have a sink, the water goes down and drain it? It's sink. A lot of people. You have trouble with that word.

Thank you. You're the communicator. But what about having, we've tried to talk also about what farmers can do to grow different kinds of crops or maybe in the off season what to do with their soil. What are some of the suggestions here? Oh, yes, surely. So there are cover crops. So for a long time, there are some farming systems. would actually, and this is, I think, part of the problem in Brazil right now with the burning.

So they would burn the residues of the crops and sometimes even plow up and have just the bare soil. Well, that is, that plowing action is just basically providing conduits pathways for carbon dioxide to be emitted from the soil. If farmers use cover crops, especially, for example, legumes that provide nitrogen to the soil, they're simultaneously reducing their greenhouse gas emissions, and they are also enriching the soil for their next crop. Farmers must be receptive to these ideas, right? Well, you know, farmers are stewards of the land. And when we think about how farmers can help, and the report also had a great team of policy specialists and policy experts, again, not telling any country what to do. But one of the things they brought forward was things like incentives for farmers to store up carbon using their soil as sponges for carbon. I don't understand why a good incentive is your grandchildren.

I agree with that long term. Why do you need to have such monetary incentives all the time just to know wouldn't you like to leave something over for your grandchildren? Absolutely. The long-term intergenerational equity, we called that, is very important. But, you know, we need to get going on these solutions now. You think? Are you kidding? You know, so this idea of what can we do?

do now, such as soil carbon sequestration, but you know what? Just doing a better job, growing crops, because then the roots will store more carbon. Do we have, I mean, can we do both? Can we feed a growing world and also be a good steward? The report gives a resounding yes to the answer to, as the answer to that question. Not all the scenarios, in scientists, we use a lot of scenarios into the future. Not all the scenarios have this. If we do bioenergy in very, very large-scale monocrop ways, not paying attention to the environment,

we can run into competition between bioenergy for solving climate change and food production. But if we work on sustainable land management of both the bioenergy growth, cropping systems, as, and for example, with the second generation of, with switchgrass, you know, those C4 grasses, warm season grasses, as well as being very good stewards of our, our food production, the report comes forward and says, yes, we can, but we need to start now. We need to start soon. We need to scale up, and we need to do this really carefully. I'm Ira Flato.

This is Science Friday from WNYC Studios. Talking with Cynthia Rosenzweig, a senior research scientist at NASA Goddard Institute for Space Studies, one of the lead authors of the new IPCC report on climate change about agriculture. I think we have a couple of questions. Yeah, let's go to the phones. Let's go to Greg and Baton Rouge. Hi, Greg. Hey, how you doing?

Hi there. I just wanted to know if that report touches on aquaculture at all. There are a lot of stories out there about, you know, the comparative efficiency and sustainability of aquaculture versus traditional animal crops. And I just wondered if you guys had a chance to delve into that. Dr. Rosenblank? The report looks at aquaculture on land in freshwater situations because there is another special report coming out of the IPCC, which is going to be, I think, coming out in September, which deals with oceans and the cryosphere. So the marine aquaculture is handled there, but we did look at, but in our food security chapter, we included aquaculture, and it certainly can play an important role. That's fish farming.

Yes, fish farming. What about algae or some of alternative sorts of foods? Did you look into those? Yes, we did. In particular, on the meat question. So there are now beginning to be technologies that are looking at cultured meat. They are looking... Fony meat.

I had a great phony hamburger the other day. They're looking at cellular. That's the cultured meat. from cellular development. And we even did, we also looked at the literature on insects because insects are high-protein sources of food. So what we found was this is early days for the work on these alternative protein sources. They may play a role in transition.

Right now, it's hard to say what their carbon footprint will actually be. And that's what in any kind of food production system, you have to look at what the carbon footprint is. That could be pretty strenuous to find out exactly what that is. Let's go to a tweet. Diana on Twitter wants to know about the potential of regenerative agriculture. Do you know what she's talking about? Well, we look at – there's a whole set of agricultural techniques that have been developed under different rubrics.

One of them is conservation agriculture. One is agroecology. One is climate smart agriculture. And we do, in the report, look at that. I'm not sure we looked at regenerative specifically. But there are all these great techniques that are coming together under these groups who are following these. And those can very much play a role.

In particular, diversification in agricultural systems, getting away from this monocultural systems, getting away from this monoculture commercial industrial farming that has, that has, you know, is one end of the spectrum. But diversification can help in regard to being resilient to the climate changes because increased extreme events. We also have to. It's happening. It's happening.

And we've got to adjust to them. So not only do we have to be feeding more people, we have to be reducing our greenhouse gas emissions from our agricultural systems. we also have to be getting those to be more resilient to the extreme events. Dr. Rosenzweig, thank you very much for taking time to be with us today. Cynthia Rosenzweig, senior research scientist at NASA Goddard Institute for Space Studies, lead author on the new UNIPCC report on agriculture. We're going to take a break when we come back.

We can talk about the iconic features of this summer night skies, fireflies, everything you wanted to know about them. We'll talk about it after the break. Stay with us. This is Science Friday. I'm Ira Flato. You know, one of the key signs that summer is here is the flickering of fireflies. Haven't we all tried to catch one, right? Catch them when you were a kid. Watch them light up, put them in a jar. This bioluminescent beetle captures our imaginations. But how much do we really know about fireflies? Do you know the difference between a firefly, a lightning bug, and a glow worm? Do you know that? And are firefly populations in trouble? How healthy are? How healthy are?

My next guests are here to walk us through all these burning firefly questions. Let me introduce them to you. Sarah Lauer is an assistant professor of biology at Bucknell University in Lewisburg, Pennsylvania. Sarah Lewis is the author of the book Silence Sparks, the Wondrous World of Fireflies. She's also professor of biology at Tufts University in Boston. Welcome both of you to Science Friday. Hi, Ira. Thank you so much, Ira.

Oh, it's nice to have you. One of my favorite topics. Dr. Lauer, everyone not just scientists are captivated by fireflies, but what got you interested in that? I got interested in fireflies in part from reading some of the work of our other guests, Sarah Lewis. So we go out and catch them during summer, put them in our jar, as you said, and we think we know them. They're so familiar. They're very cute. But if you look just beyond the surface, if you start to read more about them, you learn that they have incredibly interested.

biology. They have toxins. Some of them eat each other. They give each other gifts. So there's all this really interesting biology that not that many people know about. Wow, I'm glad. Yeah, let's get into that. But first I want to clear up something with you, Dr. Lewis. What is the difference between a firefly, a lightning bug, and a glowworm? Or are they just different names for a firefly, different, you know? Yeah. So, you know, here in the U.S., we sometimes people, People call them fireflies. Sometimes people call them lightning bugs.

And sometimes people call them glowworms. And it's kind of puzzling because they're not flies, they're not bugs, and they're not worms, right? Fireflies are actually beetles. But we don't call them lightning beetles. I don't understand English at all. So lightning bugs are usually is a term that's used to refer to the kinds of fireflies

that we're used to here in North America, the ones that fly around exchanging flash signals, males fly around flashing, females respond. We call those lightning bugs, especially in the South. And glowworms is a term that is used more generally around the world to refer to a bunch of different kinds of insects, but mostly in the firefly world. It refers to the females of some firefly species that can't fly, right? They've got no wings, they can't fly. They just glow.

And they sit on vegetation and they glow for hours trying to attract flying males. Those are called glowworms. That's really. I know the song, you know, glow a little warm. Yeah. Great song. No brothers. We played it last time and my staff is balking and playing it again.

Oh, man. I love that song. That's what I say. Dr. Lauer, another common question is, where do the fireflies go in the wintertime? You know, when the summer is over? So generally, the ones that we see in the summer are the adults. A lot of species are only living for about two weeks as an adult. So they have their two weeks.

They find a mate. They lay eggs. And over the winter, those, well, over the rest of the summer, the fall, all those eggs are hatching out into larvae, and those larvae are growing, and they are eating. They're searching for worms and slugs and snails on top of the soil, and they will overwinter as larvae. They'll pupate in the springtime and emerge as adults in the summer. Now, there's one group of fireflies that actually has the opposite characteristic, where they

actually come out in the fall, and they actually exist. They persist on trees over the winter. These are the winter fireflies. They're all in a group of fireflies called Elycnia. And so we found the first ones out around us this past spring, February 28th, after a pretty good snowfall. So they're pretty hardy then out there. Oh, yeah, those ones live a long time. 844724-8255.

You can also send us a tweet at SciFri. You know, the fireflies glowing at night seem. like a pretty big target, Dr. Lauer. I mean, why would you advertise your presence to other predators at nighttime like that? And do they have natural predators that would like to eat them? So they do have natural predators. They have, actually, there's a particular group of fireflies called Futuris that will prey upon the males of other species. So females of the group of fireflies, vaturis are called fem fatals.

and they will actually mimic the flash signals of a prey species to lure males in and eat them. And we think they do this to acquire toxins from the prey that they can then put into their own eggs to protect those larvae from predation. Other organisms that really like fireflies are spiders, so wolf spiders, all sorts of spiders that you go out in the field and you see firefly stuck in webs a lot. I didn't know that. That's quite interesting. Dr. Lewis, the common traits of fireflies is not that the adults glow, but that the larva glow in every species. Why would a larva need to glow?

Yeah, so it's really interesting. You know, people wonder why we call the fireflies that don't light up at all during their adult lives. Why we still call them fireflies? And you've just provided the answer, which is that, well, they're genetically related, and all juvenile fireflies can light up. So even as juveniles, those fireflies light up. They lose that ability once they become adults. Other fireflies keep that ability when they're adults.

And so this is actually a really cool thing that firefly scientists have discovered just in like the past 20 years is how fireflies actually make their light and how they control their light and where it came from in the beginning. And so we've discovered that fireflies first fireflies light producing talent, first evolved in that juvenile stage that Sarah was talking about, the ones that live underground, they spend a long time in that juvenile stage, and imagine being a soft-bodied little kind of grub-like thing that lives down in the soil. How are you going to advertise that you're toxic? So we know that these juveniles contain nasty tasting chemicals. How do you advertise those chemicals if it's dark and you can't have like the classic warning colors

of orange and black and red that we see in the daylight world. So we think that firefly larvae's evolved their ability to make light by a luminescence as a warning signal. It's a highly visible sign that they originally used to warn off predators saying, hey, I'm toxic. You don't want to eat me. That is kind of interesting, but it also answers a question I've had many years ago. I know a scientist who many years ago

was attempting to make shark repellent out of firefly lanterns. Is it because of that nasty tasting chemical what you talk about that might be suspected of as being a good shark

repellent? You know, it could be. I really don't know. The nasty tasting chemical is yeah, it's called Lusufigen. and as Sarah said, it's one of the things that wards off most predators, like birds, will not eat fireflies, toads don't eat fireflies, lizards don't eat fireflies.

And so it's possible. It could ward off sharks. I doubt that it evolved for that reason, though. Let's go to the phone. Let's go to Joe in Phoenix. Hi, Joe. Hi, how's it going? Hi there.

Go ahead. Okay, so a few years ago, I was in Hollywood. behind the Hollywood Bowl up in the Hollywood Hills, and I was very attentively listening to a radio head concert. And I looked down on the ground, and what I thought was like a glow bracelet, or the end of a glow bracelet, was a glowworm. It was green.

The very tip of it was glowing green. And I know we don't have glow bugs in, or at least fireflies in California around Hollywood, but there was a glow worm. So what was it? Okay, let me, thanks for the question. Let me bring a tweet in and ask the same question. Maybe we can do two for one.

Aaron tweets, my family and I recently saw desert fireflies glow worms at the north rim of the Grand Canyon. Quite a surprise, as we had always understood, that fireflies lived east of the continental divide. Sarah, what do you say about that? So, which Sarah wants to answer this question? That's right. And you both have L's in your name. I'd be glad to give it a go. Go ahead.

So, yeah, this is one of the myths about fireflies is that there aren't any, there aren't any on the West Coast. There are actually fireflies on the West Coast, and there's a lot of them. Some of them belong to this group that Sarah just talked about, which are the daytime dark fireflies, the elycnia fireflies. And some of them are glowworm fireflies where the females are flightless. So what you saw at the Radiohead concert was probably a California peasant. pink glow worm. And these are the flightless females of species of firefly that lives actually all up and down the coast of California. And it's really quite common. If you check out I Naturalist, which is a citizen science website, you can see the observations for the California

pink glowworm, just like a whole bunch of them up and down the coast. So I'm really glad that you had a chance to see that. There also are, so just in the last few years, we've discovered, scientists have discovered that, yeah, there are actually lightning bug fireflies that show up in isolated pockets in the desert southwest, in Utah and Arizona and other places. And they're restricted to moist places. So fireflies need moisture in all of their life stages. The adults need moisture, the females need a moist place to lay their eggs, the larvae need moisture. So if there's a desert seep or, you know, a small stream in the West, you can actually often find fireflies around those. And there's the Utah Natural History Museum has a whole firefly website with sightings of fireflies around the southwest.

That's terrific. Here is. Here's a question on Twitter from photo site who asks, how is, Firefly Luciferin biosynthesized. I thought about this for about five years, and I still don't know. Sarah, I'm going to let you answer that. I can take that one. So the answer is we don't know.

So fireflies light up in chemical reaction, and two of the really important ingredients are called luciferase and luciferin. Luciferase is a protein that's made by the firefly. We've actually found it in the genome of the firefly. And it works on its substrate, luciferin, so you need these two ingredients together to make light. We still don't know how luciferin is made. So that is one of the burning questions in the firefly world is where does it come from? Is it made by the fireflies?

Is it made by an organism that lives inside the firefly? Does it come from their diet? We do not know. Wow. I'm Ira Flato. This is Science Friday from WNYC Studios, answering your burning questions about fireflies. We had a couple people on Twitter comment that they had seen fewer fireflies over the years, Dr. Lauer. And I know when we were kids catching them in jars, we thought we were going to get, you know,

we'd get rid of all of them that way. Do we, is the firefly population declining over the years? So, just as you said, you know, think about your childhood and remember more fireflies then. For the longest time, we scientists were just dealing with these reports about firefly declines, these anecdotes from people that you would meet when you go out in the field or give talks. Just recently, we've been starting to get enough long-term monitoring data from different scientific groups, but also from citizen scientists. So as Sarah mentioned, the I-Naturalist platform where you can actually take a picture of an organism that you see submitted online. and a scientist, an expert, will identify that picture for you and add it to a growing list of database of sightings.

We can use this massive data over time now to start tracking firefly declines. In addition, there's another program that is specific to fireflies called Firefly Watch. Sarah, would you like to talk about that? Sure, yeah. I'd actually also like to talk about some of the, our fireflies really declining.

And so, you know, it's a really interesting thing. It's sometimes, yes, they're declining and sometimes no. And there are kind of two threads to follow in this story. So just like other insects, fireflies go through population fluctuations, right? They have good years. They have bad years. We know now that warm, wet springs are really, really good for the juvenile fireflies that Sarah mentioned.

So these conditions are responsible for producing a bunch of, of fireflies, like the one that we had this year. I know there were a lot of fireflies in New York, in New York City this year. But it's also really important to keep in mind that there are 2,000 different species of fireflies around the world. And some of these are really weedy. They can live anywhere, the adults and the juveniles. But some are very, very picky.

They can only live in special places. We call those habitat specialists, right? They only live in particular places. And many of these habitat specialists are the fireflies that are declining because their habitat is disappearing. Nice, I hear you. I have two questions. I want to see if I can get them in 30 seconds each. Let's go to Mike and Akron.

Hi, Mike. How are you doing? Quickly. I was wondering about the synchronicity that some fireflies undergo and they all laid up at the same time and what kind of advantages that may have. Okay, let's see. Which Sarah wants to answer that? Sarah Lewis? I'll give Sarah Lauer a chance on this one. So the synchronicity, there's a couple of species that will do this.

There's synchronizing ones. So you may have heard of this species, Fatinus Carolinas, that's on the east coast of the U.S. There's a really big viewing area in the Great Smoky Mountains. And what is the advantage of that? I'm trying to get this answer in quickly. So, yeah, so the advantage of that is, that all of them signaling together, they can have greater reproductive success.

An individual male has greater reproductive success in finding a female if they all signal together. In Malaysia, where they all gather together and signal in a single tree, we think that this is having a specific area where females know to go where males are and mating can occur. Quick question, quick answer.

How do you attract them to your yard in 10 seconds? Sarah Lauer? extract them to your yard. Don't apply. Keep your lights off, so we want to minimize light pollution. You want to make sure that you're providing spaces for their prey. So they're eating worms and slugs and snails. You need some moist nutrient-rich environment with leaf litter.

No pesticide. They seem to really like tall grass. All right. There you have it. We've run out of so many questions so little time. You can read more about it in Sarah Lewis's book, Silent Sparks, the wondrous world of fireflies, and also Sarah Lauer is Assistant Professor of Biology at Bucknell University in Lewisburg. Thank you both for taking time to be with us today.

Thanks for having us. You're welcome. If you missed any part of the program, you can subscribe to our podcast. Also, you can have our smart speakers ask to play Science Friday whenever you want. Oh, so much great stuff about fireflies and all the other stuff we talked about today. So stuff to talk about over a beer tonight if you're having one. Have a great weekend. I'm Ira Flato in New York.

Thank you.