Entomophthora mucae, a parasitic fungus, goes to great lengths in order to seduce houseflies. A recent study found that the parasitic fungus Entomophthora muscae has created a powerful aphrodisiac after taking control over a fly's brain, and sent it to death at the highest possible point.
This love potion ignites the passion in healthy male flies and encourages them to have the opposite sex. Sometimes this means that the female carcasses are bloated and literally bursting at the seams with spores.
Nature's desire to reproduce is so strong that it makes a great target for hijacking. Many organisms harness this power of lust, including plants that disguise their flower as female insects to lure males to do their dirty pollen-carrying job, and fungi that trick female spiders to mat with infected males.
Two potential mates can be locked onto one another in blind attraction and their decision-making skills may become compromised.
Researchers at the University of Copenhagen conducted experiments to prove that zombie fungus can exploit this vulnerability to an amazing extent. Although their work has not yet been peer reviewed, it is available on bioRxiv's preprint server.
Andreas Naundrup, an ecologist and his team gave male flies the option of mate with infected or non-infected females in the same testing area. Although there was no obvious difference in which carcass the male chose, it was more common for the male to mat with the remains of infected females if the female was in the later stage of spore production (sporulation).
The researchers incubated male flies for ten days to confirm that the increase in fly sexiness was indeed beneficial to the fungal infection. Nearly three quarters (75%) of males were exposed to females at the late stage of sporulation. This compares to 15% of the males who attempted to infect carcasses in the early stage of sporulation.
Naundrup and his colleagues measured the male housefly antenna responses to volatile compounds around living flies, uninfected corpses, and sporulating corpses. The most attractive were again dead sporulating women.
The team discovered a distinctive chemical profile in long-chained esters and alcohols when they compared chemicals using mass spectrometry and gas chromatography of uninfected fly species.
The researchers tested these chemicals on flies and concluded that they work well together to attract males.
The team wrote in their preprint paper that E. muscae causes changes in volatile chemistry to attract house flies. This is done by altering cuticular fly hydrocarbon levels and producing a variety of unusual volatile compounds.
These compounds are attractive to other insects, such as bumblebees, but not known in house flies. Researchers suspect that more volatile chemicals could be used to lure flies from afar, while weaker signals tap into their reproductive instincts.
The team examined gene expression and found that E. muscae expressed key enzymes in late-stage sporulation. This is known to produce these compounds.
Although the fungal disease may infect house flies with an animal epidemic, it's not specific to them. It can also infect other species of flies like hoverflies and blowflies.
Once the spore has reached a suitable host, it forms a root-like mycelium that reaches the part of the brain responsible for controlling the insect's crawling behavior. It manipulates the fly to climb up to a higher spore-releasing height while also eating its flesh and creating its own reproductive organs.
This fungus not only has the frightening ability to zombify its host but also has the amazing power to manipulate healthy fly species it has yet touch. This example of chemical mimicry exploiting animal mating urges is one of the first descriptions of such extended behavior-manipulation by a pathogen, Naundrup and team explain.
They suggest that the findings could lead to the discovery of semi-chemical house fly-specific attractants and pheromones for pest control.
The desperate need of a parasite to spread itself can lead to some truly evil tactics.
These results can be found in the preprint section of bioRxiv.
