Really weird, mind-control zombie fungus sees flies meet a gruesome end

1 Aug 2018

Fruit fly. Image: Salvatore D’Oro/Flickr (CC BY-NC 2.0)

After seeing the destruction left by a weird, mind-control fungus on her fly population, a researcher set out to find out more about it.

Like almost all life forms, fungi will go to great lengths to make sure it lives on by finding ingenious ways to spread its spores.

One particularly effective but gruesome way has just been analysed in great detail by University of California Berkeley researchers Carolyn Elya and Michael Eisen.

In a paper published to eLife, the pair documented a fungus that can invade the nervous system of a fruit fly and then eat it from the inside out.

Before the fly meets a grisly end, the fungus is able to take control of the creature’s body and force it to reach a high point and spread its wings. In doing so, the fly’s abdomen is exposed, allowing the fungus to shoot out its spores from the dying fly at a great height, possibly infecting new flies.

The rather gruesome discovery was made by Elya after rotting watermelon was left on her balcony, and a number of dead fruit flies started surrounding it over time. Realising what might be happening, she brought fruit flies from her lab to the scene of carnage and, lo and behold, they too became infected.

Infected fruit fly

An infected fruit fly stuck to a support by its proboscis, a trick engineered by the fungus to keep the fly positioned optimally for spreading its spores. Image: Carolyn Elya/UC Berkeley

The ‘destroyer of insects’

Not only is the fungus really weird, Elya added: “I thought this was a big, bad, evil thing crazed with infecting lots of flies, but the fungus is actually pretty wimpy.”

Upon further inspection, the researchers found that this ‘wimpy’ fungus was Entomophthora muscae, or the ‘destroyer of insects’.

While the fungus has been known about for 160 years now, Elya was able to discover that it invades the fly’s nervous system very early in the process.

For anyone feeling sorry for the fly, there is some comfort in the fact that, during the whole process, it is totally clueless as it goes about its business. It is only when the fungus has consumed all of the fly’s fat does the behaviour appear odd.

By the time the fly raises its wings at an unnatural 90-degree angle and freezes in place to release the spores, it is already dead.

“As far as I can tell, it holds off on eating the brain until after it kills the fly,” Elya said. “That’s also when it eats the muscles.”

Now, the researchers want to better understand how the fungus gets the fly to climb.

Fruit fly. Image: Salvatore D’Oro/Flickr (CC BY-NC 2.0)

Colm Gorey was a senior journalist with Silicon Republic