Zombie Ants Saved By Fungus-Castrating Fungus
Ophiocordyceps unilateralis s.l. is a fungus that invades an ant’s brain and causes it to march off to its death at a mass grave near its ant colony. Fungus spores then grow out of the ant’s head and infect other ants — but scientists at Penn State University have found that it’s not all curtains for an ant colony if one of its members is infected.
A parasite — a “hyperparasitic fungus” — comes to the rescue by attacking the fungus that turns the ants into zombies. As lead researcher David Hughes says, it’s “a case where biology is stranger than fiction.”
As Hughes, an assistant professor of entomology and biology and a member of the Center for Infectious Disease Dynamics at Penn State, explains in a press release:
“The hyperparasitic fungus effectively castrates the zombie-ant fungus so it cannot spread its spores. Because the hyperparasitic fungi prevents the infected zombie-ant fungus from spreading spores, fewer of the ants will become zombies.”
Prior to conducting their research (which has been published in PLoS ONE), scientists knew that ants seek to protect themselves against infection from microscopic spores through efficient grooming. They’ve now learned that Ophiocordyceps unilateralis s.l. “castrates” the zombie-ant fungus such that “only about 6.5 percent of the spore-producing organs of the zombie-ant fungus” are viable. Even though there are “a lot of dead and infected zombie ants in the neighborhood” of an ant colony, only a few healthy infant ants end up infected by mature spores of the zombie-ant fungus.
That is, the lethal fungus that attacks the ants’ brains (and manifests itself as a stalk growing out of an ant’s head) is itself attacked by no less than another fungus.
Hughes says that he and his research team will continue to study “the exciting theatre played out on the rainforest floor.”
Or maybe he should call it the fungus-packed grade B horror movie occurring in farflung corners of the world!
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Photo by ggallice