Scientists Discover Fungus That Attacks Zombie-Ant Fungus

Posted on May 5, 2012

Zombie Ant Fungus Stalk Castrated by Hyperparasite Fungus


A research team, led by David Hughes of Penn State University, has discovered a fungus that attacks Ophiocordyceps, the zombie-ant fungus. The zombie-ant fungus is a parasitic fungus that infects ants and controls their behavior. An infected ant leaves the colony and finds a leaf, which it bites down on. The ant is killed by the fungus and dies anchored to the leaf by its own bite. After the ant is dead a weird stalk emerges from its head, which releases spores into the air that can potentially infect other ants.

The ants have a hero in the battle against the deadly zombie-ant fungus and that hero is another fungus. This hyperparasitic fungus castrates the zombie-ant fungus and prevents it from being able to spread its spores. This fungus then helps curb the spread of the zombie infections in the ant colony.

Hughes says, "In a case where biology is stranger than fiction, the parasite of the zombie-ant fungus is itself a fungus -- a hyperparasitic fungus that specializes in attacking the parasite that turns the ants into zombies."

As part of their research, the scientists created a detailed model that revealed previously unknown details of the interactions between the fungus-infected ants and the parasite-infected zombie-ant fungus. Scientists previously had known that ants defend their colonies against microscopic enemies such as fungal spores by efficiently grooming each other. In this study, the researchers also modeled the effect of ant behavior on limiting infection. The scientists report that only about 6.5 percent of the spore-producing organs of the zombie-ant fungus were viable.

Hughes says, "Even though there are a lot of dead and infected zombie ants in the neighborhood, only a few of the spores of the zombie-ant fungus will become mature and able to infect healthy ants. Our research indicates that the danger to the ant colony is much smaller than the high density of zombie-ant cadavers in the graveyard might suggest. This complex interaction between ant colonies, their brain-manipulating parasites, and other fungi capable of lending assistance to the colony underscores the need to study social insects under natural conditions."

The research about the discovery of the parasite that defends ants by attacking the zombie-ant parasite can be found here in PLoS One.

Photo: David Hughes, Penn State University