Zombie cicadas: WVU team unearths manipulative qualities of fungal-infected flyers

Monongalia

MORGANTOWN, W.Va. – The noise of cicadas is unmistakable, even the look of them, but do you think you would be able to identify a zombie cicada?

They are cicadas with up to half of their bodies missing, as a result of parasitic fungus Massospora, and fly around as if nothing is wrong. This is according to West Virginia University researchers who stated that the infection not only causes them to lose parts of their bodies, but also act in manipulative ways to spread the disease.

A WVU press release explains that Massospora manipulates male cicadas into flicking their wings like females – a mating invitation – which tempts unsuspecting male cicadas and infects them. Matt Kasson, a WVU professor on the research team, said while the phenomenon is interesting it is not prevalent.

Matt Kasson

Fascinating but really only impact a small percentage of the overall cicada population, so not a really a threat to the future stability of the cicada population. But at a local level, you can find significant infections. For example, last year we were over in Powder Mill Nature Reserve, which is up there in Pennsylvania and there was a pretty high rate of infection, I would say 20-25 percent of cicadas were infected. That was a real hotspot, but overall, it’s probably less than 5 percent on the overall landscape.

Matt Kasson – WVU Associate professor of plant pathology and mycology 

It is still not understood where the disease originated and how cicadas become infected. Kasson said there are a couple of theories, one is that they are infected underground during their 17 year period before they reemerge. The second is that they become infected before they go back into the ground and the disease stays dormant for almost two decades.

Lifecycle of cicadas (WVU Photo)

Regardless of the prevalence, Kasson said, understanding how the disease initiates in cicadas could be very important to understand how this and other fungi attack and kill other insects. What they know so far is that the fungi produce psychoactive compounds and provides a really good hypothesis of how their behavior is being manipulated to act like zombies.

This psychoactive compound, which researchers said contains chemicals including those found in hallucinogenic mushrooms, could also explain how the cicadas manage to fly around with half their bodies missing, without even noticing.

“We still have to test a lot of these things,” Kasson said. “We are one step closer to understanding these systems, but there is still a lot that happens literally below the ground and we can’t see what is happening. I’m hoping in the next few years we can really further understand this system enough to make an impact on the overall community of research that’s being done.”

(WVU Photo/Angie Macias)

Kasson explained that because of the long period of being underground, he and other researchers have to travel to where broods are emerging because they would have to stay around in one spot for 17 years. He said they were in Morgantown in 2016, North Carolina in 2017, upstate New York in 2018 and Southern Pennsylvania in 2019.

He said all the periodical cicada populations have shown signs of the infection.

According to the release, as grotesque and as an infected decaying cicada sounds, they’re generally harmless to humans.

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