Deadly Attraction

Often the subject of science fiction B movies – a seemingly inert blob which can consume lifeforms around it – is not just the stuff of fiction.

A fungus ( Entomophthora muscae ) survives by infecting common houseflies with deadly spores.

The fungus has a unique tactic to ensure for its survival. It ‘bewitches’ male houseflies and drives them to necrophilia with the fungal-infected corpses of dead females.

Scientists from the University of Copenhagen and the Swedish University of Agriculture Sciences in Alnarp, studying the pathogenic fungus have found that after having infected a female fly with its spores, the fungus spreads until its host has slowly been consumed alive from within. After roughly six days, the fungus takes over the behavior of the female fly and forces it to the highest point, whether upon vegetation or a wall, where the fly then dies. When the fungus has killed the zombie female, it begins to release chemical signals known as sesquiterpene

Henrik H. De Fine Licht, an associate professor at the University of Copenhagen’s Department of Environment and Plant Sciences, explained:

“The chemical signals act as pheromones that bewitch male flies and cause an incredible urge for them to mate with lifeless female carcasses.”

A male fly trying to mate with a female corpse held in place by a dab of Vaseline. The fungus has grown out of the rear body segment and is visible as large white patches from which spores are ejected. Image credit: Filippo Castelucci

As male flies copulate with dead females, the fungal spores are showered onto the males, who then suffer the same gruesome fate. In this way, Entomophthora muscae spreads its spores to new victims and ensures for its survival.

Henrik H. De Fine Licht. said:

“We see that the longer a female fly has been dead, the more alluring it becomes to males. This is because the number of fungal spores increases with time, which enhances the seductive fragrances.”

Click on this link to access the paper, Pathogenic fungus uses volatiles to entice male flies into fatal matings with infected female cadavers

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