A Fungus Is Causing Cicadas to Have Too Much Sex

If you feel like you’ve been enjoying just a bit too much of the world’s natural beauty lately, don’t fret! For here we have news so thoroughly disgusting, it will put you off even the notion of hiking to the market. There’s a fungus preying on cicadas in the US and it’s making them hypersexual. The fungus is also ripping out the cicadas’ abdomens, killing them in an incredibly gruesome way.

NPR reported on the major fungal infection, which is now affecting Brood X; a trillions-strong swarm of cicadas in the midst of infesting the northeast and central parts of the US. The brood, like all the other 15 periodical broods in the US., has long intervals of dormancy. And it’s only now coming out of a 17-year-long period of hibernation below ground.

But a fungus called Massospora is infecting some single-digit percentage of Brood X. Scientists believe the fungal spores infect the young cicadas—or “nymphs”—as they dig tunnels to the soil’s surface, where they eventually break through as adults.

Apparently, the infection involves two main stages. The fungus begins the first stage completely concealed within infected cicadas’ abdomens. After it grows and eats away at its hosts a bit more, Massospora causes the cicadas’ abdomens to fall off. This revealing a white, chalky mass that looks like a plug. (That plug is on the bottom half of the cicada in the image below.)

Matt Kasson

These “flying salt shakers of death”—yes, scientists refer to Stage I cicadas by that name—then proceed to Stage II by sprinkling spores everywhere. These spores then go on to infect the next generation of cicadas when they burst from the ground.

It’s during both stages that the cicadas’ sexual behavior becomes quite strange. In order to maximize its odds of reproducing, Massospora infects its host cicadas with an amphetamine that causes them to lose control sexually. Male cicadas with the infection will begin to mount other males when they otherwise wouldn’t, for example. Even cicadas with lost abdomens will engage in vigorous sexual courtship, leaving their genitalia plunged into the abdominal spore mass of an infected partner. (Note the cicada in the video below from Bug of the Week is still completely mobile despite the loss of its abdomen.)

Matt Kasson, an associate professor of forest pathology and mycology at West Virginia University, told NPR: “Something that’s being manipulated by a fungus, to be hypersexual and to have prolonged stamina and just mate like crazy [is] stranger than fiction.” Apparently Massospora affecting yearly broods use psilocybin—the chemical in psychoactive mushrooms—instead of an amphetamine. Which makes that death method more or less appealing depending on how much time you usually spend “tripping” through nature.

Feature image: Matt Kasson