Zombie Ants

A fatal fungus is responsible for turning seemingly innocent ants into zombies.

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It is half past midnight. Up in the sky is a glistening full moon. There is a certain chill in the air, one that you cannot quite shake off. The russet-colored leaves under your feet crunch with every step, hinting at a moderately chilly Halloween next weekend. Coincidently, you are also standing in the middle of an ancient, abandoned graveyard. Still, there is one thing missing: zombies. Perhaps a couple of rotten-fleshed humans will start climbing out of their graves. Or maybe some zombie ants. In fact, you do not have to resort to fiction to hear about such insects.

These so-called “zombie ants” are infected with Ophiocordyceps, a fatal fungus that causes their creepy behavior. When an ant goes out to forage for food, the fungus strikes by attaching its fungal spores to the ant’s exoskeleton. This can stop all muscle movement, leaving the victim twitching and paralyzed. While scientists previously believed that the fungus invades the ant’s brain, new research suggests that the fungus releases certain biological compounds that can influence the ant’s nervous system and, thus, control its movement.

First, the ant is usually forced to move to a more humid climate favorable to the fungus and extremely uncomfortable for the ant. Then, the fungus will force the ant to sink its jaws into a leaf or twig. Unable to move, the ant is forced to wait for death. Meanwhile, the fungus devours the ant’s insides and then uses its corpse to covertly infect other ants, repeating the process.

The fungus’s formidable behavior has only left scientists with more questions. In a study conducted by Charissa de Bekker, a molecular biologist at Pennsylvania State University, and her colleagues, they infected four distinct species of ants with the Ophiocordyceps fungus, allowing it to “zombify” the ants, and then extracted the chemicals released by the fungi. Upon inspection, many of the thousands of chemicals were unknown. However, the team managed to identify two specific compounds that are likely responsible for zombifying the ants: guanidinobutyric acid (GBA) and sphingosine, which happen to play a role in certain neurological disorders like Parkinson’s Disease. Other studies conducted by de Bekker’s team also suggest that the fungus can recognize different brains in ants and choose to infect its preferred host. While further research needs to be done, current information has led scientists to hypothesize a connection between these zombie-causing fungi and future cures for specific neurological disorders. Perhaps by identifying the chemicals that control the ant’s nervous system, scientists can develop treatments that help subside the symptoms of these disorders.

Studying this fungus not only helps in fighting neurological disorders but also provides an insight into how to fight fungal infections. Fungal diseases kill over 1.7 million people a year. Studying this intriguing fungal infection in ants is easier and faster than studying fungal infections in humans, given ants shorter life spans. Additionally, fungi are more closely related to animals than plants. Thus, something that would kill an ant would likely kill human cells as well.

For now, we do not have to fear an infection from any fungus similar to Ophiocordyceps. Though it sounds like it came out of a Hollywood horror production, the fungus is not as cruel as it is depicted. In fact, it helps keep the ant population under control—a classic display of nature’s balance. Overall, there are more than 200 types of this fungus that infect a wide variety of insects, including spiders. Perhaps a few zombies are much less scary than a world overridden by spiders and ants.