Zombie Ants and the Cordyceps Fungus

Zombies are one of the most popular pop culture horror tropes and have been gracing the silver screen, TV, and video games for a generation. While mostly given a supernatural explanation, some works of fiction try to give a more-or-less scientific explanation for their walking dead, whether it’s a virus, parasite, or some other pathogen.

Surprisingly enough, a parasitic zombie pathogen actually exists in the real world. The Cordyceps fungus will infect unsuspecting carpenter ants, compelling them to spread the affliction before dying. This sinister form of mind control is just as horrifying as your favorite zombie flick and is an example of the ingenuity of insect parasites in the natural world.

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Cordyceps: The Zombie Fungus

Cordyceps is a genus of parasitic fungi that includes about 600 species. Most species of Cordyceps are parasitic and feed on insect and plant hosts, as well as other species of fungi. Cordyceps fungi are common in humid rainforests and exist around the world. Many species are valued for their medicinal properties.

One species of Cordyceps, called Ophiocordyceps unilateralis, has developed a form of reproduction straight out of Resident Evil. O. unilateralis will infect carpenter ants, working its way into their bodies and hijacking their minds. The fungus changes the ant’s behavioral patterns, causing it to leave its colony and seek out a long, tall plant stem. Once there, the ant is forced to sit until the fungus bursts out of its head, releasing spores that will go on to infect other ants.

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The worst part? The fungus will make the ant occupy a place close to its colony. So when the fungus breaks out of the ant’s exoskeleton, it will rain down on the pitiable colony. So not only does it hijack the ant’s body, but it also turns it against its allies. O. unilateralis typically targets carpenter ants, but it also infects other closely related species

Scientific study of O. unilateralis reveals surprising properties not found in other parasitic fungi. Individual cells will first enter the insect’s body, before forming large, tendril-like structures that spread through bodily tissue. As the fungus matures, these tendrils form a large stalk-like structure that pushes its way out the ant’s head, releasing spores into the air. The overall maturation cycle takes between 4 and 10 days.

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While normally considered a single organism, O. unilateralis acts more like a supercolony of smaller entities that work together to wrangle control of a larger organism’s body. Perhaps most surprisingly, though, is that Cordyceps fungus doesn’t actually infect the ant’s brain. The truly incredible aspect of O. unilateralis is how it can coordinate such precise behavioral control, without actually touching neuronal tissue.

Scientists believe that O. unilateralis may directly control the ant’s limbs by effectively cutting off brain control, putting the fungus in the driver’s seat. As such, an ant infected with Cordyceps may end its life as a silent prisoner, trapped within its own body—truly the stuff of horror!