EDIT: Thanks so much for your questions! I had a lot of fun answering them, but I’ve gotta run now.

Hi! I’m Dr. Matt Kasson, a mycologist/plant pathologist and Associate Professor in the Division of Plant and Soil Sciences at West Virginia University. I also serve as director of the International Culture Collection of (Vesicular) Arbuscular Mychorrhizal Fungi (INVAM)—the world's largest collection of its kind, which is housed at WVU. My specialty is fungal biocontrol, tree canker diseases, and fungus-arthropod interactions. I also study fungus-cicada interactions and fungus-ambrosia beetle interactions. In addition to my work with cicadas, as a 2021 National Geographic Explorer, I focus on exploring and characterizing fungal biodiversity associated with fungus feeding millipedes, which represent some of the earliest land animals. Looking forward to your questions!

Additional information on me can be found here: https://on.natgeo.com/3udZLDt

And for more information about my work with millipedes, click here: https://on.natgeo.com/3wuc1kR

Hear from me on the latest episode of National Geographic’s Overheard podcast: https://on.natgeo.com/3uflgUJ

Proof: https://i.redd.it/53ywem3qi4171.jpg

Comments: 76 • Responses: 18  • Date: 

nobackup_4239 karma

Flying salt shakers. Please enlighten?

nationalgeographic95 karma

When Massospora infects a cicada it doesn’t kill it. In fact it hijacks the typical behaviors of healthy cicadas like flying. So when infected cicadas fly around with a mass of spores erupting out from the end of its abdomen, spores fall down like salt grains from a tipped salt shaker. Those spores can then infect unsuspecting cicadas below.

ForkShirtUp25 karma

Of death. Don't forget that part. If they went around salting our sidewalks and roads for the winter or giving our grilling steaks a little bit of seasoning that's fine. But the death part sounds sketchy

nationalgeographic40 karma

The phrase was coined by my grad student at a time when our understanding of these fungi was incomplete. Based on our observations, this pathogen doesn’t shorten the lifespan of cicadas compared to healthy counterparts. This makes sense as the fungus only has a few weeks every 17 years to proliferate. But let’s remember that this is effectively sterilizing cicadas either consuming existing eggs in the abdomens of infected mated females or preventing reproduction altogether. That in itself is death of the next generation.

human_stain21 karma

When I first heard about this fungus and cicadas, it was described as "a STD that makes their butt fall off", and then makes a fungal mass that spreads where their abdomen was.

I have made no effort to look it up further, but can I ask you to comment on that colorful description and correct it, please?

nationalgeographic36 karma

Certainly the headlines are sensational regarding Massospora infected cicadas. The reality is the fungus does consume the back end of their abdomen which includes their genitalia. The fungus replaces these tissues and then infects via the genitalia of healthy cicadas during mating attempts. In this way it is sexually transmissible even if that sexual attempt is unsuccessful.

N8teface11 karma

Thank you for doing this AMA! How do these fungi benefit from targeting periodical cicadas specifically? It would seem difficult to rely on a 13 or 17 year cycle.

Similarly, have the cicadas in any of the broods evolved a defense against this parasitism?

nationalgeographic21 karma

There are over a dozen described Massospora species that infect either annual or periodical cicadas. It does seem like a huge risk to co-evolve alongside an animal that spends only a few weeks above ground every seventeen years. But fungi are patient and the payout is exceptional.

SlightlyAlmighty7 karma

Does this fungus act like the one that turns ants into zombies? How does it affect the cicada population regarding numbers (does it work as a population number controller)? Thanks for this specific and really interesting AMA!

PS: do people call you a fun guy at parties?

nationalgeographic4 karma

It’s similar in that it modifies behavior but the behaviors are quite different. The zombie ant fungus directs its host to an elevated position where it affixes, dies, and the fungus then erupts out. With Massospora, the cicada remains alive and its regular activities such as flying and attempting to mate maximize spore dispersal!

brassmorris5 karma

Is this process at all similar to the pscilocibe fungus that infects cicadas?

nationalgeographic6 karma

The behavioral manipulation by both Massospora species is essentially the same. We suspect psilocybin in infected annual cicadas and cathinone in infected periodical cicadas may serve similar functions.

wockyman3 karma

What're your thoughts on the recent Scientific American article?

nationalgeographic5 karma

Fungi continue to pose threats to animals and plants! We need to continue to invest in basic science to ensure we are prepared to respond to the next emerging disease.

Leenzlions3 karma

Hi there! How did you get interested in studying fungi and cicadas? And what’s something you wish other people knew/appreciated more about your field?

nationalgeographic7 karma

I owe my interest in cicadas and their fungi to my grad students. They got me hooked! Fungi are incredible and perform such critical yet overlooked services in our environment! For example, if fungi didn’t degrade downed woody debris, our forests would be mile high piles of wood.

circa_diem3 karma

I noticed that some of the shed exoskeletons around my house have little white strings sticking out from the insides. Is this the fungus?

Also, does this prevent them from mating or egg laying? Will the population be smaller the next time around?

nationalgeographic5 karma

No that’s trachea!

Zealousideal-King-473 karma

When does the fungus first infect the cicadas? And does this fungus infect other insects/animals? Is there any possible effect of the fungus on humans?

nationalgeographic7 karma

From all the literature that exists on this interaction as well as our own observations, cicada nymphs first interact with the overwintering spores of Massospora as they await just below the leaf little in the days to weeks leading up to emergence. Periodical cicadas are the only known hosts. The fungus poses little risk to anything or anyone else.

NOSlurpy3 karma

Do the cicadas taste better with or without the fungi? Asking for a friend...

nationalgeographic3 karma

Not sure. I would not eat a fungus-infected cicada!


Is there any concern for humans or other animals handling, breathing, or ingesting an infected Cicada? (besides other Cicadas)

nationalgeographic6 karma

Although stimulants have been reported by our lab group from Massospora infected periodical cicadas, the risk to us is extremely low given the dosage detected from individuals.

theriveryeti2 karma

I’ve heard more about fungi in the last year than I’ve heard my whole life, especially as they interact with trees and forests. Was there a giant breakthrough in the last few years regarding the basic nature of fungus?

nationalgeographic4 karma

Certainly fungi have been doing incredible things for millions of years. We are only now starting to understand how crucial they are in many living things! I think the field of mycology is in a really productive phase right now unlocking some of the most perplexing mysteries!

hobokittypurrever2 karma

Hi! do you think this fungus will effect the next brood or is this just a once in a lifetime thing?

nationalgeographic2 karma

All broods of both 13 & 17 year cicadas are susceptible to this fungus. It generally has little impact on the overall reproductive success of these species across the larger landscape!

Serendipia01 karma

Is Massospora fungi present in Mexico?

nationalgeographic1 karma


SnakeCharmer281 karma

There are some really good questions here. So I have a softball question: What's your favorite fungus?

nationalgeographic6 karma

That’s like asking who is my favorite kid. I love all fungi!

K-9Tx1 karma

I would love your opinion on why or what advantage the fungus has when it’s using a host who comes out so infrequently, and is this of any benefit to the cicada species as a whole?

nationalgeographic2 karma

It’s an extremely specialized lifestyle with a huge payout.

Jackalodeath1 karma

Fleeting curiosities, feel free to ignore for more engaging convo.

First: Cicadas are loud, and while I'm sure you're not exactly in an enclosed lab with those things screaming away at all hours of the day, any hearing protection required on the regular?

Secondly: its believed some (or all, just learning about it,) Massospora can produce psychoactive chemicals or effects in their hosts, is it known if this is how the fungus "convinces" the cicada to take flight and "carpet bomb" its fledgling cousins with a bad case of buttrot?

I won't bother with the "any signs it causes pain/discomfort" thing since that not exactly easy to measure, and if it can "convince" the host to go on a joyride after making its ass fall off I'm sure it can trick whatever version of nerve endings they have not to feel it (also considering they still try to do the sexy time when their sexy time parts are lying on the forest floor somewhere, but that could just be their "programming.")

nationalgeographic3 karma

Decibel wise, cicada noise likely falls between bar conversations and lawnmower noise. So prolonged exposure could impact hearing assuming you are sitting among them as they call.

It’s true about the compounds and although they provide a plausible explanation of how behavior is modified, further study is needed. We are working on that.