Fungus That Seduces Male Flies to Have Sex With Dead Females Could Be Used as Insecticide


Nov 4, 2021


Image Credit: Fillipo Castelucci

Under the influence of aphrodisiac-like chemicals, male flies are having sex with corpses of female flies. Who’s responsible for Romilda Vane-ing them with the “love potions,” you ask? Well, it’s a fungus that is driven by its agenda to lure as many flies to their death as possible.

“If you see a dead housefly on a windowsill surrounded by a ghostly halo of tiny white spores, it’s a death trap,” Science reported, explaining that “the [dead] insect was invaded by a fungus that took over its brain, manipulating the fly to find the highest perch it could. From there, the fungus launched its spores into the air to infect as many healthy flies as possible.” 

Additionally, of course, they lure male flies to mate with the infected cadavers. In fact, this serves a dual purpose: first, the males who come into close contact with the corpses while mating get infected; second, the “vigorous mating” releases a cloud of spores to infect other unsuspecting hosts.

This “death trap,” grim as it might sound for the naive males who just wanted to get laid, can advance research into the usage of insect-killing fungi. In the past, this fungus — Entomophthora muscae — has already been studied as a potential biological control agent due to its ability to fatally infect house flies. The present study has added further backing to that potential.

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The prospect of a fungus doubling up as an insecticide is indeed fascinating — especially so, since chemical-based pesticides and insecticides not only contaminate the environment, but can also be toxic to animals consuming the plants treated with chemicals. Not just that, they can also harm the human nervous system, endocrine system, and reproductive system.

Just this August, researchers had discovered a wild tobacco plant, too, that could potentially serve as a natural insecticide since it was found to trap and kill insects. With E. muscae, we now have yet another contender for natural insecticides.

Authored by scientists from Denmark and Sweden, the present study found that healthy male flies were about five times as likely to try to mate when the female’s life had been claimed by the fungus E. muscae.

“It’s almost like an aphrodisiac, maybe driving [male houseflies’] sexual behaviors to a supernormal level,” explained lead author Andreas Naundrup, whose research at the University of Copenhagen in Denmark focuses on organismal biology.

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The researchers believe “a grassy, somewhat sweet smell” of the fungus was “part of the appeal.” Moreover, the female flies infected with the fungus were found to contain a lot more methyl-branched alkanes than healthy flies. The longer a fly had been infected, the more the chemicals. And these chemicals are, reportedly, known to stimulate male house flies to mate.

Naundrup told the reporters that dead houseflies, perched with their wings spread, can actually be spotted both indoors and outdoors — making it possible for us to actually watch this Fatal Attraction-esque mating unfold. “If people are interested in this, my advice would be to stop and — I wouldn’t say smell the flowers — but stop and watch the flies,” he advised.

His team admitted to being amazed by the ability of the E. muscae to manipulate and exploit the sexual desires of its hosts. “I’m really impressed and amazed by the extent of the adaptation it shows,” said Henrik de Fine Licht, an evolutionary ecologist at the University of Copenhagen, who co-authored the study.

Carolyn Elya, a molecular biologist at Harvard University, who wasn’t involved in this study, called its findings a “big step forward” towards finding a natural way to deal with houseflies.


Written By Devrupa Rakshit

Devrupa Rakshit is an Associate Editor at The Swaddle. She is a lawyer by education, a poet by accident, a painter by shaukh, and autistic by birth. You can find her on Instagram @devruparakshit.


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