Beware .... Zombie Ants

Original Article Here.   Zombie ants, the ghostly slaves of a mind-controlling fungus seen creeping around places like South America for years, have now been spotted in the United States. But don’t panic—they’ve probably been here all along, and we only just now noticed.

Scientists at Penn State have for the first time shown that a fungus here in the U.S. invades the brains of ants, manipulates them into a very specific spot in the forest, and kills them before raining down spores on their comrades.

 ...Then in 2009, Penn State’s David Hughes stumbled across the Flickr feed of a woman named Kim Fleming, who had found and photographed ants infected with the mind-controlling fungus in her backyard in South Carolina. He and his team have been working with her to describe the remarkable zombification ever since.

 ... A fungus spore lands on the cuticle of an ant, fusing to its body and building up an incredible amount pressure (equal to that in the tire of a 747 jet) to blow itself through the exoskeleton. Infiltrating the ant’s brain, it directs the host out of the colony, where workers would surely notice their comrade’s weird behavior and drag it into a graveyard well away from home base. Directing the ant up onto the underside of a leaf at a specific height and always facing a specific direction, the fungus orders the ant to bite down on the vein. At this point it kills the ant and erupts as a stalk out of the back of its head, raining spores onto its comrades below.

The fungus goes through all of this trouble to best position itself to infect more ants and further its own species. Simply killing its host, like it did to the two other ant species in de Bekker’s lab, doesn’t get it anywhere, because ants are obsessive about dragging their dead and dying into their aforementioned graveyards, where the spores have little chance of spreading.

Interestingly, this North American species of Ophiocordyceps controls its victims a bit differently than its South American counterparts. “What is different about the temperate system is that these ants don’t bite the leaves, they bite twigs,” said de Bekker. “Which is actually very interesting, because of course in a temperate system the trees lose their leaves over the winter, and sometimes dead ants have to overwinter into the next season for the fungus to completely grow out and make the spores and finish its life cycle.”

A zombified ant clamped down on a twig, before the emergence of the fungus stalk. Kim Fleming

Reference:
De Bekker, C, et al. (2014) Species-specific ant brain manipulation by a specialized fungal parasite. BMC Evolutionary Biology. 14:166 doi:10.1186/s12862-014-0166-3