In truly creep news, a team of scientists has announced that a known fungus causes male flies to mate with the bodies of dead females. The strategy helps ensure the survival of the fungus, as it spreads from the females to the males.
For the study, researchers from the University of Copenhagen and Swedish University of Agriculture Sciences observed populations of houseflies (Musca domestica), the females of which had become infected with a parasitic fungus known as Entomophthora muscae.
It was determined that about six days after the initial infection, the fungus took over the behaviour of the females, causing them to climb to the highest point in their immediate vicinity. The flies died soon after, at which point the fungus began releasing chemical signals called sesquiterpenes.
These signals reportedly acted as pheromones, drawing in male flies that proceeded to copulate with the corpses. As they did so, fungal spores spread from the dead females to the live males, subsequently infecting them too.
Making things even … yuckier, the males preferred to mate with females that had been dead for some time. More specifically, it was found that 73 percent of males preferred to copulate with corpses of females that had died 25 to 30 hours earlier, while only 15 percent preferred females that had perished three to eight hours ago.
“We see that the longer a female fly has been dead, the more alluring it becomes to males,” said U Copenhagen’s Assoc. Prof. Henrik H. De Fine Licht. “This is because the number of fungal spores increases with time, which enhances the seductive fragrances.”
The research is described in a paper that was recently published in The ISME Journal.
And as a side note, this isn’t the first known instance of a fungus controlling a host insect’s behaviour. Ophiocordyceps unilateralis (aka zombie ant fungus) causes infected ants to travel to the underside of a leaf and clamp onto it with their mandibles, after which they die and provide an optimum growing environment for the fungus.
Source: University of Copenhagen