Parasitic Fungus Makes Ants into Infection-Spreading Zombies

A parasitic fungus that spreads by infecting carpenter ants can essentially make an ant into a zombie to carry its spores, a new study has found.

The fungus, technically known as Ophiocordyceps camponoti-rufipedis, doesn't take direct aim on a nest; instead, it latches onto worker ants on the colony's outskirts to make them into carriers, Live Science reported.

"What the zombie fungi essentially do is create a sniper's alley through which their future hosts must pass," researcher David Hughes of Penn State University said in a statement. "The parasite doesn't need to evolve mechanisms to overcome the effective social immunity that occurs inside the nest. At the same time, it ensures a constant supply of susceptible hosts."

The scientists, who have published their findings in PLOS ONE, analyzed an ant colony in Brazil and discovered that the fungus couldn't survive on ant corpses that were placed inside the actual nest. The fungus stalk couldn't grow properly, and healthy worker ants took the dead bodies out of the nests after several days.

"Ants are remarkably adept at cleaning the interior of the nest to prevent diseases," Hughes said. "But we also found that this fungal parasite can't grow to the stage suitable for transmission inside the nest whether ants are present or not. This may be because the physical space and microclimate inside the nest don't allow the fungus to complete its development."

The fungus spreads best by hitching a ride on worker ants and making them into zombies. The carpenter ants that have been taken over by the parasitic fungus are led away from their nests made to climb plants in the rainforest's canopy.

Grabbing onto the underside of a leaf and then dying, the carpenter ant acts as a vehicle for the fungus, which sprouts a long stalk from the ant's dead body to rain spores down on other ants that are searching for food.

The research team reported an average of 14.5 infected ant bodies for each colony per month. The parasitic infections were termed a "chronic disease" since the ant colonies neither collapsed entirely nor got rid of the fungus altogether.