Fungus Turns Cicadas Into Sex-Crazed Zombies: NPR

Some of the cicadas that temporarily invade parts of the eastern and southern United States are transformed into sex-hungry “zombies,” thanks to a fungus that removes their genitals but still causes them to continue mating.

Cicadin Massospora has been observed in cicadas in more than half a dozen states – both those belonging to Brood XIII, which emerges every 17 years and concentrated in Illinois, and Brood XIX, a group of 13 distributed across much of the southeast.

This is the first time these two specific broods have co-emerged since 1803 – and it’s not the only strange (or some might say, spooky) fact about them.

The fungus is easy to spot because it replaces the back of the cicada with what looks like a “white, chalky blob of gum,” according to Matt Kasson, a professor of forest pathology and mycology at West Virginia University.

Kasson told NPR last month that the fungus is unique because it performs “active host transmission,” meaning it keeps the cicada alive — and flying — even after about a third of its body is was replaced by fungal tissue.

“It’s the puppeteer – the mushroom – that pulls the strings of its unsuspecting host,” he said. “This keeps the host active in trying to mate and spread the spores.”

As part of this effort, the fungus also makes cicadas hypersexual. Typically, male cicadas emit a loud mating call to attract females, who respond by flapping their wings. Infected males, in their fungus-fueled quest for world domination, will also pose as females to mate with other males.

Their attempts to reproduce, doomed from the start, only fuel the spread of the virus, a group of scientists at the Field Museum of Natural History in Chicago told NPR.

“Eventually, their fungal cap is torn and they fly around raining down spores, further spreading the fungus,” they wrote. “Some scientists call cicadas at this stage “flying salt shakers of death.” “

Periodical cicadas only live about three to four weeks once they emerge from the ground, so this year’s crop will begin to dwindle later this month. But the fungus will persist.

Cicadas infected at “stage I” transmit the disease to other adults of their same generation, according to the University of Connecticut. “Stage II” cicadas disperse their spores into the soil, where they will infect the next generation of cicada nymphs in 13 to 17 years.

We don’t know how many cicadas are infected, or if they are “crazy”

Kasson says not to worry about the well-being of infected cicadas, in part because of another curious side effect of the fungus.

“Turns out the mushroom produces a stimulant called cathinone, which probably means the cicadas don’t care because they might be crazy,” he wrote on X (formerly Twitter).

A study published in Fungal ecology in 2019 reported the discovery of cathinone – a plant-associated amphetamine – in four populations of infected cicadas, and the hallucinogen psilocybin in some annual cicadas infected with the fungus.

Field Museum scientists say these natural amphetamines can affect not only cicadas but also larger animals that feed on them, such as birds. But the quantity is so small that there is no risk to people or pets.

Scientists don’t know exactly how widespread Massospora is or how many of the billions of cicadas buzzing around the United States will be affected.

Field Museum researchers, for example, identified only seven infected cicadas out of the “hundreds” they examined during a visit to central Illinois last week.

Kasson estimates the overall incidence of infection at “perhaps below 5%” – but not everywhere.

“We have encountered some areas where this rate is as high as 20 to 30 percent,” he said, adding that his team was trying to understand the reasons for such variation. “With climate change and landscape fragmentation, all of these things, cumulatively, could tip the scales against cicadas and really impact a specific brood.”

He says his team has collected more data over the past decade on 17-year-old cicadas, and so hopes to get their hands on more infected cicadas among the 13-year-old population – as well as those in the 13-year-old population. Illinois where the two broods overlap geographically.

Kasson also encourages observers to alert him to any specimens they might want to contribute to his research, and tweeted this week that “the only way to truly learn about periodical cicadas and their zombie cicada fungus, Cicadin Massospora, it’s driving out to meet them in person. (He found 18 live infected specimens on his first day in the Chicago area.)

Anyone hoping to approach an infected cicada – or avoid it at all costs – can rest assured knowing that the Massospora poses no risk to humans.

“The fungus also specializes in cicadas, so other animals and humans cannot become infected with it,” Field Museum scientists wrote. “They are safe to handle (but you may want to wash your hands after).”