#6: Cicadas: Unexpected Ambassadors of Biodiversity

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Cicada Episode

[00:00:00] Griff Griffith: Welcome to a world where the hum of nature symphony takes center stage. That mesmerizing chorus of thousands of cicadas blending together in harmony.

[00:00:13] And guess what this year, it’s a double feature in some parts of the United States, two distinct groups of cicadas are rising up simultaneously Turning 2024 into a cacophony of nature’s finest.

[00:00:29] There are special kinds of cicadas that spend over a decade underground and somehow, some way they all decide to emerge at the same time.

[00:00:37] How can millions of insects collectively make these decisions?

[00:00:42] but there’s a deeper story buzzing beneath the surface. It’s a tale of survival of predator and prey dancing in a delicate balance. It’s about adaptation, evolution, and yes, even danger lurking in the wings.

[00:00:56] Matt Kasson: When a cicada is infected with Mesopora, basically the Posterior or the back part of the abdomen comes off and from underneath emerges a chalky white gumdrop or maybe something analogous to powdered sugar or chalk dust

[00:01:16] And those plugs are basically millions of individual spores that then get transferred as they fly around, as they attempt to mate. We call them flying salt shakers of death It’s kind of a pretty metal term,

[00:01:33] Griff Griffith: Gross. Is he describing a sexually transmitted fungus? We’ll hear more from Dr. Kasson about this in a few minutes. Regardless, cicadas in their standard form or as flying salt shakers of death are more than just background noise.

[00:01:47] They’re a living testament to the intricate web of life where every species, no matter how small, plays a vital role, not just to ecosystems, but also food webs. In fact, cicadas have been eaten by people too for thousands of years.

[00:02:01] Cicadas reflect what it means to have biodiversity and abundance. So even if you don’t have these kinds of cicadas in your area, similar stories are playing out all around you.

[00:02:10] So buckle up because we are about to embark on an extraordinary journey into the wild world of cicadas and how they embody the importance of biodiversity.

[00:02:18] I’m Griff Griffith, and welcome to Jumpstart Nature.

[00:02:31] You’re listening to a special kind of cicada, a periodical cicada. , periodical because they only emerge after a set period of time. In United States, different groups emerge after either 13 or 17 years.

[00:02:55] If you’re like most people, the thought of cicadas probably conjures up memories of loud or maybe even annoying insects of mid and late summer screaming from the nearby trees.

[00:03:04] And based on those recordings, I can’t blame you, but these cicadas are a bit different. Dr. Chris Simon is considered the world’s foremost expert on these unique cicadas.

[00:03:14] Chris Simon: Ah! They’re spring cicadas and they’re small and black with red eyes. None of the annual cicadas in the United States have red eyes and there’s huge numbers of them all over. When they first come out. You can see ’em all over the trees and bushes, and then they climb up into the tops of the trees

[00:03:36] the smaller two are much louder and much more annoying, the largest one. The Decim group, they have a nice calm whistle sound and it sounds like flying saucers from a 1950 science fiction film. If you go into an area and you ask people if they’ve heard anything, it sounds like a flying saucer. And the cicadas are there. They’ll, the Decim ones, they’ll say yes. So it really does sound like flying saucers.

[00:04:04] Griff Griffith: Okay, to help set the stage, here’s a sample of what a 1950s flying saucer sounded like And now here are a couple recordings of Decim cicadas The first one is a group singing as a chorus.

[00:04:24] And here’s one isolated with a chorus in the background. Okay, yeah, I can hear it a little, but I think the cicadas sound a bit more like the alien probes from the original War of the Worlds movie.

[00:04:41] Gene Kritsky: There are seven species of periodical cicadas in the eastern U. S. There are three species of 17 year cicadas. And there are four species of 13 year cicadas. Now within those seven species, there are essentially three species groups.

[00:04:55] Griff Griffith: Dr. Gene Kritsky has been mapping where these cicadas occur for close to 50 years. From here, things get complicated pretty fast, so with the help of our experts, I’ll try to break things down in simple terms.

[00:05:07] The groups of cicadas Dr. Kritsky mentioned are lumped together because they look and behave similarly.

[00:05:12] Despite being similar, each group has both a 17 year species a 13 year So yes, the most closely related species seem to have different life cycles offset by four years.

[00:05:24] when we have a mass emergence, like we’re due to have any day now in 2024, We don’t just see one species or one group emerge. Rather, we see distant cicada cousins spanning different groups and species deciding to come out at the same time.

[00:05:38] Whew! So are all these cicadas sitting around coordinating their plans?

[00:05:43] I have so many questions! But wait, there’s more!

[00:05:47] Chris Simon: So each species has a whole bunch of reproductively isolated groups. And these are so recently isolated in different years that they haven’t formed new species yet, but they’re in the process of becoming species because they’re reproductively isolated.

[00:06:07] Griff Griffith: All right, so we have speciation in progress. That is, for whatever reason, one species of cicada, or more accurately, groups of different species, Have banded together to emerge from underground But the same set of species that emerges in Illinois in 2024 on a 17 year schedule might emerge in Pennsylvania in 2025, but on a different 17 year schedule.

[00:06:29] since these groups emerge in different years and locations, they are reproductively isolated. They never see each other as adults, and as a result, don’t exchange genes. Given enough time, they will become distinct species.

[00:06:42] These groups of cicadas that emerge in different places at different times are called broods. It’s important to note that cicadas have their own unique definition of brood. In other animals, a brood usually refers to a group of young cared for by specific parents, like with birds.

[00:06:59] Chris Simon: Yeah, the word year class would be much better than brood because as you said, it’s used in birds to mean that the individual’s in a nest

[00:07:07] Griff Griffith: So we have seven current species of periodical cicadas in the United States.

[00:07:12] Chris Simon: we used to think that they were the only periodical cicadas, but oh, maybe in 2014 we uncovered this little newspaper, article, a little blurb that said World Cup Cicada. And it turns out that the cicadas come out in the year, like in the spring, right before the World Cup. So I found the publications, it was published by a scientist in Northeast, India. I contacted him and it turns out that they also discovered another group that’s nearby that’s offset by two years, same species, but it’s got two broods offset by two years.

[00:07:52] And then in a book written by a cicada biologist about the South Pacific, he mentions a cicada that might be periodical in Fiji. We checked it out and sure enough, it does seem to come out once every eight years.

[00:08:09] Griff Griffith: These Fiji cicadas will emerge in 2025. That’s just enough time for someone to fund a jumpstart nature trip to Fiji

[00:08:16] so we can personally investigate. Nat Geo, Animal Planet, Bill Gates. Are you listening?

[00:08:23] Fiji dreams set aside for the moment. You Periodical cicadas are just a blip in the big picture of cicadas.

[00:08:32] Dr. Matt Kasson is also a biologist who has an entirely unexpected path to cicadas. And we’ll discuss that a bit later. But first,

[00:08:40] Matt Kasson: late August, we have something called the Dog Day Cicadas, because we hear them during the hottest dog days of summer.

[00:08:47] And they’re the really loud, obnoxious ones that scream, scream at you while you’re out at your picnic table or grilling. and those are commonly heard, but not really seen like the periodical cicadas. So that’s an example of an annual cicada

[00:09:01] Gene Kritsky: There are 3, 400 species of cicadas worldwide. But those come out every year,

[00:09:07] Chris Simon: the annual cicadas are bigger, wider and some of the annual cicadas are much bigger. There’s some very tiny little cicadas, say for example, we know of some in Australia that are maybe the size of your fingernail. And then there’s some very large cicadas also in Australia and New Guinea, tropical areas. I would guess maybe six inches long, something like that.

[00:09:32] Griff Griffith: I’ve been a nature nut for decades, so I’m not always surprised to learn that some animal or plant has more diversity than I expect, but 3,400 species of cicada, wow. One other thing I’ve come to expect is that every species has a wonderfully unique way of interconnecting with the rest of nature.

[00:09:50] Gene Kritsky: They do a lot of ecological good when they come out. So, for example, the holes in the ground that they produce as the nymphs emerge is like a natural aeration and in our hot summers when the clay soil starts getting baked really hard and we get that heavy rains instead of running off, a lot of that water goes down those holes and helps water the trees later in the summer.

[00:10:09] when the adults are flying around, they’re food for all sorts of opportunistic predators unlike the annual cicadas, periodical cicadas, their survival strategy is to have come, come out such massive numbers. That birds, dogs, cats, raccoons, deer, I’ve seen turtles eat these things. I’ve seen snakes eat these things, have all the cicadas they want to eat. And there’s still millions left.

[00:10:31] And that means those predators will have more of their offsprings survive that year.

[00:10:37] Griff Griffith: Imagine if you woke up one day and your house was swarming with your favorite chocolates. You’d probably eat a few, maybe a lot. And this goes on for days. Eventually you’d get tired of eating them. This is what happens with cicadas. Dr. Kritsky continues:

[00:10:50] Gene Kritsky: , when the females lay their eggs in the terminal growth of trees and the branches sometimes break, and the leaves turn brown, we call that flagging, that’s like a natural pruning.

[00:11:00] And the next spring, the trees will produce a larger leaf set and flower set that helps them to recover. And then finally, the cicadas die after they’re done laying their eggs. And let’s face it, they can come out in numbers there. Now this is under trees, but they’ve been measured up to one and a half million per acre of tree coverage.

[00:11:20] That’s a lot of bugs. When they die, they collect at the base of trees, because they’re all up in the trees, and they start to rot. And that rotting, as they start to decay, all those nutrients from all those millions of cicadas goes into the soil around the base of the tree. Forming a, a nutrient cache for the tree.

[00:11:39] Chris Simon: there’s a huge pulse of nutrients into the soil. And that’s been studied by Louie Yang at Davis who’s shown the real importance of the cicada bodies as fertilizer for growing plants.

[00:11:52] Griff Griffith: Those are just a few of the benefits of cicadas. and many cultures worldwide have long seen cicadas as a culinary delight. Recognizing the nutritional value of freshly molted cicadas, indigenous Americans gathered them into baskets and prepared these abundant snacks in various delectable ways. Even today, cicadas are savored as a delicacy in many parts of the world. You can even buy cicada pizzas in parts of the United States.

[00:12:15] however, the early colonists mistook cicadas for,

[00:12:18] Chris Simon: Locust they used to be called 17 year Locusts and 13 year Locusts I think they got that name during Colonial times because the colonists in Massachusetts were not doing that well. There was just like one plague after another.

[00:12:33] And then all of a sudden all of these cicadas came out. They were all over everything. And so they thought it was a plague of Locusts like in the Bible.

[00:12:42] Griff Griffith: and Sadly, some of their misconceptions have persisted through the generations, leading some people to believe they are harmful pests. It’s important to dispel the myth that cicadas pose a threat to gardens or pets. cicadas are not interested in devouring your plants or harming your beloved pets

[00:13:00] In nature, every action sets off a chain reaction, sparking a dance of reaction and adaptation among plants and animals. Over millennia, these interactions weave themselves into the very fabric of The Ecosystem .

[00:13:13] As cicadas continue to speciate, evolving into new species right before our eyes, This dance becomes ever more intricate and grand, like a ballet expanding into a spectacular ensemble performance. Each new dancer adding their unique steps to enrich the ecosystem.

[00:13:29] Sometimes this dance takes a disturbing turn, or at least disturbing if we look at it through the lens of humanity. Matt Kasson again:

[00:13:37] Matt Kasson: Oftentimes when people think about fungi, they think about mushrooms. And it’s true that all mushrooms are fungi, but not all fungi are mushrooms. The mushroom forming fungi is just one branch on the fungal tree.

[00:13:53] Entomopathogen is the word we use for an insect infecting or an insect destroying fungus. And Massospora cicadina is an entomopathogenic

[00:14:03] fungus. That means it infects insects, primarily cicadas.

[00:14:08] Griff Griffith: There are many types of fungus that target insects.

[00:14:11] Matt Kasson: let me, , take you on a visual journey. , imagine a cicada, , their body is made up of these, plates of, chitin.

[00:14:20] usually black in color. When a cicada is infected with Massospora, basically the Posterior or the back part of the abdomen comes off and from underneath emerges something analogous to a, an eraser on a, on a pencil, , covered with, um, powdered sugar or chalk dust. And that is the fungal plug of Massospora .

[00:14:44] And those plugs are basically millions of individual spores that then get transferred as they fly around, as they attempt to mate. We call them flying salt shakers of death. It’s kind of a pretty metal term, , but it’s also visually informative. , if you were to imagine a cicada with a salt shaker, duct tape to its back, flying around, you would see, you know, salt, shaking out everywhere.

[00:15:13] And that’s similar to what’s happening with these spores on the back end of the abdomen.

[00:15:17] Griff Griffith: The ballet has suddenly turned into a heavy metal mosh pit Alright, alright, enough of that. and it turns out different fungal species infect other types of cicadas too, it’s all part of the dance and this fungus takes control of the cicada much like how music can take control of our dance.

[00:15:40] Matt Kasson: in order to talk about cicada behavioral modification in the presence of a Massospora, I want to quickly just talk about behavioral modification in other insects by fungal pathogens. , there’s a really common type of behavioral modification called summit disease. And even if you’ve never heard that term, you’ve certainly seen it because zombie ants , are the like iconic example of this.

[00:16:08] , what happens is a lot of insect pathogens coerce their hosts to climb to a high elevation, affix, , or lock into place, whether that’s biting down or, or, you know, digging in, , after which the insect dies and the fungus, you know, dies. erupts quite cinematically out of the cadaver. That’s the zombie ant fungus.

[00:16:35] That’s what The Last of Us is based on. , some of you may know the video game or the HBO series.

[00:16:41] So that’s one behavioral modification, but that’s not what Massospora does. Massospora is actually way cooler because it does something called active host transmission. That is, it keeps its host alive. as long as possible to maximize its dispersal.

[00:16:57] Griff Griffith: If you’re wondering how an animal can have its posterior fall off and seemingly go about its normal routine, so am I.

[00:17:03] Matt Kasson: Well, despite the fact that a third of the abdomen, including the genitalia of these cicadas, have They continue to fly around as if nothing happened. They continue to engage in normal behavior, just like their uninfected counterpart. There’s a prolonged wakefulness in them that is beautifully disturbing, if I might say.

[00:17:30] In addition to this prolonged wakefulness or this kind of hyperactivity, We also see what we characterize as hyper sexualization. For example, a male that’s infected with Massospora will not only continue to try to mate with females, will himself pretend to be a female to get healthy males to come in contact with him.

[00:17:56] , what underlies all that? , that was really a question we had from the beginning, is why is this hypersexual behavior happening? Why is this prolonged wakefulness happening? And it turns out, , well, it’s drugs. In fact, uh, we found in Massospora cicadina, , a production of a compound called cathinone.

[00:18:15] Now, cathinone is a naturally occurring amphetamine,

[00:18:18] Griff Griffith: Ah, they’re hopped up on amphetamines. Have you heard those crazy stories about what people do when they abuse drugs called bath salts? these were causing people to become excessively alert, aggressive, and even giving superhuman strength during rage filled outburst. That was the same amphetamine that controls these cicadas.

[00:18:36] With millions of cicadas left over even after predators partake in the cicada buffet, it’s no wonder that some pathogen found its niche among this abundance.

[00:18:45] Matt Kasson: you know, in, in any large population, , there’s a baseline amount of disease, , that will impact the population.

[00:18:55] These obligate parasites or pathogens have really kind of figured out the perfect balance to maintaining themselves, but leaving enough of the other hosts around so that they can infect the next generation. that’s something to think about.

[00:19:12] Griff Griffith: Wow. This story has certainly taken an unexpected turn.

[00:19:16] And of course the cicadas evolution responds to the pressure caused by these fungal infections too.

[00:19:21] Kevin Wiener: My first experience, , with periodical cicadas was in Cincinnati, Ohio, uh, where I grew up, and I just remember my dad telling me, like, these stories about, like, you couldn’t even see the bark on the trees, and everything was covered, and just, they were, they were everywhere, and then the time came, and it was just really underwhelming.

[00:19:54] Griff Griffith: that’s Kevin Wiener and insect advocate, educator and founder of the popular All Bugs Go To Kevin Facebook group, describing his first cicada encounter.

[00:20:03] but 2021 saw the largest brood of cicadas emerge, and it made huge headlines. This brood is known as brood 10, but Roman numerals are used to number the broods. So it appeared in headlines like brood X.

[00:20:15] Kevin Wiener: I was excited. Super excited. I could see it through my, like, adult eyes now, Like, just knowing that it’s such an important part of, of nature to boost, , you know, populations of animals, you know, cause these are basically defenseless insects that are free for the taking for anything that, that, that eats insects. , so it can really help Populations of anything that would eat them and then in turn boost other populations of things that would eat those and so on.

[00:20:43] I was driving through Lincoln City, Indiana, I had my radio going. blaring, windows up. And then I hear this sound and I was like, there’s no way. There’s no way. And so I turned the, the stereo off, rolled the window down, and I could not believe the sound.

[00:21:08] It was so loud. And it was, I mean, I’m getting goosebumps just thinking about it now. It was just the coolest thing. And so I immediately, like, pulled over, and I just started exploring. And they were just everywhere and, uh, and high up in the trees. I mean, you just were immersed in sound.

[00:21:31] I wanted to see, I wanted to pick one up, I wanted to look at them and it’s a learning experience too, you know, because I didn’t know going in which species I was looking at, so I had to learn how to identify them because I think we had three different, , species that were popping up.

[00:21:44] Griff Griffith: Knowing a bit about the story of cicadas, their lives underground, the spectacle, what they do for nature, helped turn Kevin into a cicada fan, and his curiosity is exactly what we need to help biodiversity.

[00:21:56] But despite there being billions of cicadas, some populations are in decline. And we’re likely suffering from shifting baseline syndrome too. That is, each generation loses perspective of what things used to be like.

[00:22:09] Chris Simon: In some places they’re okay, but New England was 90% cleared in the 1800’s by the colonists with axes. And you can see paintings of the countryside at that time. And it’s just cleared, rolling hills, stone walls, trees along the edges of the walls, but mostly just completely cleared. And that’s why the New England populations are so small. And now Brood Eleven’s gone,

[00:22:36] If you’re in an area like DC Baltimore where there’s tons of suburbs, they’re surviving because there’s lots of parks as well and forest patches, and they’re doing just fine there. But if you’re in other populated areas where the trees have all been cleared and there’s a lot of asphalt and highways, so you know, when you think of them maybe moving north with climate change, it’s a little bit difficult in some places because there’s just these massive highways clearing asphalt. It’d be quite difficult to move north along the, say, I-95 corridor.

[00:23:11] Griff Griffith: Just to clarify, we aren’t expecting an emergence in 2024 in some of those areas, but if you’re curious, if you might see periodical cicadas, where you are. We have you covered.

[00:23:20] Dr. Simon and her team have excellent resources at cicadas.uconn.edu, spelled U C O N N. But as you might expect these days, there’s also an app for that.

[00:23:32] Gene Kritsky: Cicada Safari is an app, it’s a free app, , which is designed to ask our colleagues, our friends, people with an interest in natural history, to help us map periodical cicadas.

[00:23:43] Griff Griffith: People with an interest in natural history? That sounds like you! Cicada Safari is available on Apple and Android phones. Check our show notes for links.

[00:23:51] Gene Kritsky: Cicada Safari is a very easy, you walk out there, make sure your, location services are on, or your GPS take a picture of Cicada.

[00:23:58] you submit it, we have people with their eyes looking at it. It goes on the live map

[00:24:01] Griff Griffith: Contributing to community science in this way is incredibly important as we just discussed in our last episode. And yes. You can use iNaturalist as well, but Dr.

[00:24:11] Kritsky stressed that Cicada Safari is even simpler since it’s just for cicadas.

[00:24:16] Why is documenting cicadas so important? As we mentioned, populations are changing and some are declining. and you know what else is wild? Sometimes the cicada alarm clocks are wrong and no, it’s not like they’re just off by a little.

[00:24:28] Chris Simon: Sometimes, a large number of individuals will come out four years early or sometimes four years late, and that even happens in seventeen-year cicadas, and in 13 year cicadas. In thirteen-year cicadas, if you go to a place that you know is gonna be really dense and you go there four years ahead of time, there’ll be quite a few cicadas coming out.

[00:24:51] And the same for seventeen-year cicadas; if you know of a place that in the historical records, it’s very dense, and you go there four years early, you’ll see a large number of individuals coming out.

[00:25:04] Griff Griffith: these could be the start of entirely new broods and researchers need help understanding this. wow. Isn’t nature just incredible? When we started developing this episode, we had no idea that cicadas were such a perfect reflection of biodiversity and change in our environment. and as nature lovers, if periodical cicadas are emerging in your area, take this opportunity to soak it up.

[00:25:23] You may not see it again for another 13 or 17 years.

[00:25:26] Gene Kritsky: One of the important things about periodical cicadas, and this is especially true for parents of small kids, if you’re fortunate to have cicadas emerging in your backyard, the cicadas that are emerging, they emerge at night, if you’ve got cicadas in your backyard, get those kids outside.

[00:25:42] Get a flashlight. Your peripheral vision is limited because it’s dark. And you’re watching these things. Not one or two, but Tens, hundreds of them climbing up tree trunks, walls, what have you, and slowly transforming from the nymph to the adult. And that process takes about 90 minutes for the cicada to pull out, the adult cicada pull out of the nymphal skin, free itself, expand the wings.

[00:26:03] And then takes another 90 minutes to turn dark. That’s like having a David Attenborough special in your backyard.

[00:26:10] Kevin Wiener: I just want to see people get out there like, , yeah, they’re loud and they scream, but that’s how they find the ladies so that they can make more and, feed these animals that we love so much. I can talk about how exciting things are, but, like, to experience it for yourself. There’s nothing like it. And to think that I thought a lot of this stuff was just unimportant, silly, or just, just didn’t want to connect at one point in my life, I feel like I have missed out on so, so much.

[00:26:39] And I don’t want that for other people and that’s why I do the things I do and try to get people excited about the world around them and these little animals that are out there doing these amazing things, because Once you start to understand them and that they’re not out to get you, it’s pretty freaking cool.

[00:26:55] Griff Griffith: Well said. And even if you don’t get periodical cicadas in your area, look around at what does occur in abundance, or has similar boom and bust cycles that contribute to biodiversity. Perhaps it’s snow geese, sand hill cranes, or oak tree acorns. Everything is connected, and the more of these connections we have,

[00:27:11] the stronger our ecosystems are. So get outside, get curious, and look at those cicadas with a new sense of awe and a deeper meaning.

[00:27:19] If you enjoyed today’s episode, would you do me a favor and just share it with three friends or different groups that you think would like it? Also be sure to check out Jumpstart Nature on Facebook, Instagram, YouTube, and Twitter @jumpstartnature.

[00:27:32] And the full interview with Dr. Chris Simon has been released on our companion podcast, Nature’s Archive.

[00:27:37] Nature’s Archive. Check it out and see you next time.

[00:27:40] Michael Hawk: Special thanks to Dr. Chris Simon, Dr. Gene Kritsky, Dr. Matt Kasson and Kevin Wiener for lending their time and expertise to this episode. Please check out cicadas.uconn.edu, Cicada Safari, and Kevin’s All Bugs Go To Kevin Facebook group and his YouTube channel. He promises to have fresh Cicada videos as they emerge in his neck of the woods. And make sure to report any encounters with that Cicada fungi too. Dr. Kasson, will be monitoring iNaturalist for those observations. Jumpstart nature was created, written and produced by me, Michael Hawk, our host and co-writers Griff Griffith. And thanks to Kat Hill for some additional editing help. Additional information is in the show notes at jumpstartnature.com/podcast. Thanks for listening.

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