‘Zombie ant’ fungi infected with their own parasites

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Across the world, a parasitic fungus is turning ants into “zombies.”

The fungus is like something out of a horror movie: The organism hijacks its ant host’s body and brain, controlling it by controlling its mind to leave its nest and climb a nearby tree.

There, the infected ant clamps its jaws around a leaf, dangling above the forest floor, and dies within days as the fungus digests it. The fungus bursts through its host’s body and then sends down a shower of spores to infect the next generation of ant prey.

Scientifically categorized in the genus Ophiocordyceps, the more than two dozen species of zombie ants inhabit the world, including Florida, Brazil, and Japan; scientists suspect that each of the dozens of affected ant species has its own specialized strain of Ophiocordyceps.

So far, scientists have discovered the molecular mechanism of the parasitic interaction between fungus and ant that forms the basis of the behavioral manipulation, according to a 2020 study. However, exactly how these parasites work is poorly understood.

Now scientists have revealed that the ant-attacking fungus is infected with its own fungal parasites, which could help control ant zombification, according to a new study.

Dr. João Araújo, assistant curator of mycology at the New York Botanical Garden, has been trekking through tropical forests in search of zombie ants for more than a decade. Over the years, he kept noticing something strange: a fuzzy white mold growing on top of the zombie ant fungus.

Other scientists have noticed the mysterious fungus for decades, but Araújo and his colleagues decided to become the first scientists to systematically delve into the matter, targeting a species of Florida zombie ants. The researchers described the physical structure of the fungi growing on top of the zombie ant fungus and determined their DNA a study published Nov. 9 in the journal Persoonia.

In doing so, the team discovered two new types of fungi previously unknown to science.

“We realized that there were two different lineages of fungi, new lineages of fungi, infecting one species of zombie ant fungus in Florida,” said Araújo, the study’s lead author.

Each of the two newly discovered fungi belongs to its own genus. One of the new fungi, Niveomyces coronatus, is responsible for the faint white coating on the zombie ant fungus — part of its name (“niveo”) comes from the Latin for “snow.” The second new fungus, Torrubiellomyces zombiae, is harder to spot: The little black blobs “look like fleas,” Araújo said.

The fungi attacking the zombie ant fungus in turn do not zombify their host, but they do feed on its tissues and appear to harm it. “Every time we see these new genera that we described growing on the fungus, the fungus looks pretty beat up, really consumed by this other fungus,” Araújo said.

“In some cases, it first castrates Ophiocordyceps (the zombie-forming fungus) so it can no longer shoot the spores, and then it grows and consumes the entire fungus.” Because Niveomyces and Torrubiellomyces are so new to science, it’s not yet clear how much of an effect they have on zombie ant populations in general.

These new genera are the first parasites officially described as infecting the zombie ant fungus, but the researchers suspect there may be more. “I think it happens more often than we think. Parasitism is a super lucrative way of life,” says Dr. Charissa de Bekker, senior author of the study and assistant professor at Utrecht University. “It may be the most dominant lifestyle on Earth.”

In addition, she said, parasites in general and parasitic fungi in particular are poorly studied. “The fact that we had to conjure up two new genera shows how little we know about this part of the fungal tree of life,” de Bekker said.

By deepening our understanding of the zombie ant fungus, the new research could have applications beyond the study of fungi, said Dr. Carolyn Elya, a postdoctoral fellow in organic and evolutionary biology at Harvard University. She was not involved in the investigation.

“Ophiocordyceps has actually become an expert neuroscientist over the course of evolution. It knows exactly which buttons to press and how to get the ant to do what it wants,” she said. “By studying how the problem is solved, we can gain insight into our more general goal of trying to understand how brains work or produce behavior.”