A strange fungus could transform emerging cicadas into ‘saltshakers of death,’ scientists say

By Kate Golembiewski | CNN

This spring, billions of cicadas will emerge after more than a decade underground, ready to climb into the trees and make a ruckus as they sing to attract mates. But some of these insects won’t succeed in their goal of procreating — instead, they’ll be controlled like zombies into spreading a strange fungus that hijacks cicadas’ bodies and behavior.

The details of the fungus’ attack on the bugs — destroying the insects’ genitals, replacing their abdomens with a cavity full of fungal spores, manipulating the bugs into hypersexual behavior to spread the fungus further and transforming the cicadas into what some scientists term “saltshakers of death” — may seem like they belong in a creature feature horror movie. But when it comes to the fungus Massospora cicadina, said Dr. John Cooley, an associate professor in residence of ecology and evolutionary biology at the University of Connecticut, Hartford, “the truth is actually much stranger than science fiction.”

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Periodical cicadas lay their eggs in tree branches, and when those eggs hatch, the resulting baby cicadas, or nymphs, drop to the ground and burrow into the soil. Depending on their species, they spend 13 or 17 years underground, drinking sap from tree roots, until it’s time for the nearly grown cicadas to emerge. At some point, the insects are exposed to spores of the fungus Massospora cicadina. It’s not clear to scientists whether it happens when the cicadas enter the soil or when they leave it, or how that exposure happens.

How Massospora cicadina controls cicadas

The spores make their way into the cicadas’ bodies, and from that point on, the cicadas are at the mercy of the fungal parasite. A mass of fungal spores builds up in the abdomen of each infected cicada. Eventually, the back end of the cicada — including its genitals — falls off. In its place, a white fungal plug is exposed, “a clump of spores that are erupting out of where the genitals and abdomen once were,” said Dr. Matt Kasson, an associate professor of mycology and forest pathology at West Virginia University. “It looks like there’s a gumdrop that’s been dropped in chalk dust, glued to the backside of these cicadas.”

Despite having a chalky gumdrop of spores instead of genitals, the infected cicadas still attempt to mate, with gusto. The fungus manipulates the cicadas’ behavior, causing what researchers including Kasson refer to as hypersexualization. The infected males keep trying to mate with females, and they also change their behavior to attract their fellow males. Healthy female cicadas will flick their wings to indicate that they’re ready to mate. Both male and female cicadas infected with Massospora flick their wings to draw in amorous, soon-to-be-infected males.

But attempting to mate is just one part of how infected cicadas spread the fungus.

“Periodical cicadas have interlocking genitalia. So when they pull apart, guess what happens? Rip. And then there’s a cicada walking around with someone else’s genitals stuck to them,” Cooley said. “And now the cicada that’s infected is busted open.”

Once the chalky fungal plug is ripped apart, the infected and disemboweled cicada flies around, raining down fluffy, brown spores. “We call them the saltshakers of death,” Kasson said. The spores dispersed by these flying saltshakers go on to infect the next generation of cicadas that will emerge more than a decade later and begin the cycle again.

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