Fruit body of a parasitic fungus, growing out of a dead ant.
An unlucky ant inhales a spore, the fungus begins to eat the ant from inside, and, in a particularly sinister twist, Ophiocordyceps hijacks the ant’s brain. The “zombie” ant is forced to leave its nest to climb up onto a tree, clamping its jaws into a leaf vein with abnormal force. A stalk sprouts from the now dead ant’s head. This stalk is fruiting body of the fungus, which will produce new spores that rain down onto the unlucky ants below.
Ophiocordyceps seems like a lean mean killing machine in that scenario, but the fungus itself is vulnerable—to another fungus it turns out. A new paper published in PloS ONE models the disease dynamics of Ophiocordyceps with respect to ants and a hyperparasitic fungi, which is the name for parasite whose host is also a parasite. Unfortunately, this hyperparasite is not of much help for the ant, as it only infects the Ophiocordyceps after the ant has died.
The researchers collected 432 fungus-infected ants from “graveyards” in the Brazilia forest. Of these, only 6.5% had fruiting bodies that actually produced spores. Some were damaged or immature but a majority (55.4%) were hyperparasitized by a second fungi, which “castrated” the fruit bodies. What this reveals is that although many ants may become infected, only a small proportion will pass on that infection to other ants. That keeps Ophiocordyceps infections from turning into zombie ant apocalypse.
[via The Guardian]