Ophiocordyceps unilateralis is a fungus that perpetuates itself by parasite manipulation. In this case, that means making its prey kill itself (and its colony), sort of like the monster in the movie Aliens. OU infects carpenter ants by releasing spores over a colony. An ant breathes in the spore, and the spore germinates in the ant’s brain. The infected ant is then compelled to climb to an area 25 cm above its colony, where it clamps its mandibles into the underside of a leaf and anchors itself for the grim finale. The fungus hypha (or spore pod, as I understand it) sprouts out of its brain cavity, blooms, and sends down millions of spores back down over the colony, who become links in the horrid OU circle of life.
It’s a bizarre means of procreation, given that if it were unusually successful in a particular area, no carpenter ants would be left, and OU would die out as well. Fortunately, the ants have a method of dealing with the menace, namely by carrying infected ants away from the colony and leaving them to die.
Life’s tough in the rainforest.
Sources:
http://www.scientificamerican.com/article.cfm?id=fungus-makes-zombie-ants
(There's a wonderful exhibit on ophiocordyceps unilateralis at the Museum of Jurassic Technology, which is itself something a brain spore to its visitors.)
