Sexually transmitted fungi create “zombie cicadas” amid insect infestation in the US

Nature always surprises us with its unique and complex creations, and this time, the United States is preparing for an invasion worthy of a horror movie. In the coming months, “zombie cicadas” will be part of trillions of these insects that will emerge from the ground in different states, after a period of hibernation, in a phenomenon that promises to impress and scare!

The abnormal infestation of cicadas

For lovers of the unusual, 2024 promises to be an unforgettable year. According to entomologists, this year marks a rare convergence of two swarms of periodic cicadas: the Swarm XIX, which emerges every 13 years, and the Swarm XIII, which appears every 17 years. A real cicada infestation in the United States!

Together they must add up trillions of cicadas emerging from the ground in states like Illinois, Indiana, Iowa, Kansas, Kentucky, Maryland, Michigan, Missouri, New Jersey, New York, North Carolina, South Carolina, Ohio, Pennsylvania, Tennessee, Virginia e West Virginia.

Periodic cicadas spend most of their lives buried in the soil in their larval form. When temperatures reach around 18°C, they finally emerge in a deafening symphony of millions of males trying to attract females for mating. In some areas, insects will be seen and heard in numbers never recorded in the last two hundred years.

Michael Raupp, from University of Maryland Department of Entomology, ensures that cicadas do not bite or sting, but they will cause some damage to the trees. “We are incredibly fascinated by this as it will give the two litters, which are very different from each other, the opportunity to interbreed. Frankly, we have no idea what will happen.”, he said. “The only ones who know are Mother Nature and the cicadas themselves. So, it will be an extremely interesting experience!”

It is at this moment that the Massospora cicadina comes into action. The fungus, whose spores wait patiently in the soil, infects newly emerged cicadas, starting a “zombification” process worthy of a horror film. It is estimated that between 5% and 10% of these cicadas will be infected.

Within a week to ten days, the rear abdomen of infected male cicadas opens, revealing a white, chalky plug formed by the fungal spores. In a bizarre spectacle, the insects' genitals literally fall off, being replaced by this fungal mass. Despite appearing dead, zombie cicadas continue to move and behave as if they were healthy, however, their behavior undergoes a disturbing change.

Healthy male cicadas sing songs to attract females, demonstrating their willingness to mate as they flap their wings. A female unlucky enough to be seduced by the song of an infected male will not only fail to fertilize her eggs, but will also become infected, in essence turning the fungus into a sexually transmitted disease.

Infected males also flap their wings similar to females, tricking other healthy males into trying to mate with them. When they get closer, healthy males are exposed to the fungus spores, becoming equally infected and continuing the deadly cycle.

the fungus Massospora Cicadina

Scientists are studying how these fungi manage to manipulate insect behavior, seeking to understand the molecular and neurological mechanisms involved in this parasite-host relationship. One study published by PLoS Pathogens in 2020 revealed that the chemical components present in cicadas after they are infected resemble those found in hallucinogenic mushrooms.

According to the forest pathologist and mycologist Matthew Kasson, West Virginia University, Massospora Cicadina produces substances similar to amphetamines, which could explain the resistance and hypersexuality of zombie cicadas. It is estimated that a single zombie male can infect dozens from other males before succumbing to the fungus.

“We know that several species of animals, such as snakes and birds, are feeding on these cicadas. Is there a possibility that they are affecting the animals that consume them? Yes, it is a possibility.”

Matthew Kasson, mycologist

“When they fly or walk along the branches, they also spread spores”, said Casson. “We call them 'flying death shakers' because they basically disperse the fungus like salt coming out of a salt shaker.”

Um published study by Casson and his team at the magazine Fungal Ecology in 2019 pointed out the cathinone as a key compound to induce hypersexual behavior in these hosts. Cathinone is a natural stimulant from the amphetamine family, already identified as the active ingredient of the plant khat, chewed for its invigorating effects in regions Africa. Its synthetic version also makes up medications for ADHD and even illegal drugs.

Drugs based on synthetic cathinones often suppress appetite and increase focus and energy levels. It is suspected that the fungus exploits these effects, inducing obsessive mating behavior in cicadas to maximize spore transmission, to the detriment of activities such as feeding and resting. Surprisingly, some species of this fungus also show signs of psilocybin, the hallucinogenic substance in magic mushrooms.

Psilocybin and amphetamines are very different drugs, but these alkaloids may have complementary functions in suppressing appetite, increasing endurance, and prolonging periods of wakefulness.

Matthew Kasson, West Virginia University

Although the fungus' psychoactive effects generate scientific fascination, Casson makes it very clear that trying to obtain hallucinogenic experiences with the fungus from infected cicadas would be an extremely dangerous and senseless practice. The mycologist expresses concern about online discussions about this possible “recreational use” of parasitized insects.

According to him, it would be necessary to ingest hundreds or even thousands of cicadas to reach a relevant dose of psychoactive substances. In addition, insects contain more than a thousand other compounds, many of them known to be toxic to humans.

So much Casson as Chris Simon, phylogeny researcher at University of Connecticut, reassure that the risk of domestic animals or children coming into accidental contact with infected specimens is relatively low. Parasitized cicadas tend to represent a small portion of the total swarm and billions of these insects are dispersed across a vast geographic region during the mating cycle.

“Obviously, I wouldn’t recommend that anyone lick an infected cicada.”, jokes Casson. “But if a pet accidentally ingests one or two, there won’t be a serious problem.” The warning applies more to the scientific community, interested in studying the mysterious mechanisms behind fungal mind control, than to the unwary seeking out dangerous and illegal psychedelic experiments.

Similarity to the zombie ant and The Last of Us

This situation is reminiscent of the famous case of zombie ants, controlled by a fungus of the genus Ophiocordyceps. As with cicadas, the fungus manipulates the behavior of ants to ensure its spread, making them move to ideal locations for the development of their spores.

The theme of zombie insects has also gained notoriety recently with the success of the game and series The Last of Us, where a mutant fungus turns humans into cannibalistic zombies. Although these stories are fictional, the reality of fungi controlling cicadas and ants is equally fascinating and frightening.

Experts encourage people not to kill or consume cicadas, but rather to document cases through photos and videos, sharing them in online scientific communities such as iNaturalist. After all, better understanding this incredible and frightening natural cycle can help us unravel more mysteries of mother nature.

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Source: CBS News, Scientific American magazine, USA Today

reviewed by Glaucon Vital in 8 / 4 / 24.