Science Sunday: Zombie (Ant) Apocalypse
Sometimes, fact is much, much stranger than fiction. In this case, nature has got most horror movie writers beat, no question. Because deep in the Thailand rainforest, mind-control fungi are creating an army of zombie bugs. And the infection is spreading, as spores erupt from the hordes. If it was a movie, this would be the trailer (warning: it’s kind of gross, and full of insects and fungi. Watch at your own discretion):
As Sir David Attenborough mentioned, cordyceps are a kind of parasitic fungi that infect all sorts of different insects. The kind we know the most about is Ophiocordyceps, the kind of fungi that affects carpenter ants (Camponotus leonardi). When an ant inhales a spore, the fungus begins to grow inside of it. Tendrils, called mycelia, spread throughout the ant’s body and head, atrophying muscles and spreading the fibers apart. The infected ant becomes disoriented, unable to follow the chemical trails that would normally lead it home. It also starts having convulsions, a dangerous prospect when you live in the canopy of the rainforest. As the infection progresses, the fungus gets the ant to fall to the forest floor, then slowly, painfully climb back up into the understory, to find the perfect conditions. At solar noon, in the dark, damp undergrowth, the ant bites down on the underside of a leaf or stem, locking itself in place. By the end of that day, it finally dies, and the fungus takes over in earnest. A stalk erupts out of the back of the ant’s head, growing for weeks, before releasing its own spores, which then begin the horrific cycle again. According to researcher David Hughes, there are whole graveyards of these littering the forest floor.
Fortunately for the ants, there seems to be a case of fungi warfare occurring in the rainforest. With how potent these cordyceps can be, one would almost expect every ant to turn into a shuffling minion. However, thanks to an unnamed, hyperparasitic fungus, most of the fruiting bodies of Ophiocordyceps never produce spores. Only about 6%, in fact, actually are able to reproduce. This keeps the zombie fungus in check, so as not to decimate the insect population. Good for the ants, and for the environment as a whole.
While most of the research has been done on the Thai species of cordyceps, they exists worldwide. And cordyceps aren’t the only kind of fungi that parasitizes and takes over the brain of its host. Fortunately for us, though, most of these bizarre zombification infections are restricted to insects, and kept under the tight checks of competition and hyperparasitation. We’ve found no similar fungal species in birds or mammals…. yet. But the idea’s not so far fetched. Perhaps it’s worth being ready for the zombie apocalypse after all….
Featured image credit: NPR