‘Zombie ant’ fungi infected with their own parasites

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Around the world, a parasitic fungus transforms ants into “zombies.”

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

There, the infected ant clamps its jaws around a leaf, which hangs above the forest floor, dying within days when digested by the fungus. Bursting through its host’s body, the fungus then sends out a shower of spores to infect the next generation of ant prey.

Scientifically classified in the genus Ophiocordyceps, the more than two dozen species of zombie ant fungi populate 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 the fungus and the ant that forms the basis of behavior manipulation, according to a 2020 study. However, exactly how these parasites systematically operate is not well understood.

Now, scientists have revealed that the fungus that attacks the ants is infected with its own fungal parasites, which could be helping to keep ants’ zombification in check, according to a new study.

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

Other scientists have noticed the mystery fungus for decades, but Araújo and his colleagues decided to become the first scientists to systematically delve into the matter, zeroing in on a variety of Florida zombie ants. The researchers described the physical structure of the fungi growing on top of the zombie ant fungus and sequenced its DNA in a study published on November 9 in the journal Personania.

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

Dr. AS João Araújo of the New York Botanical Garden and his team discovered two new genera of fungi.

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

Each of the two newly discovered mushrooms belongs to its own genus. One of the new fungi, Niveomyces coronatus, is responsible for the white, hairy cap of the zombie ant fungus; a component of its name (“niveo”) comes from the Latin for “snowy”. The second new fungus, Torrubiellomyces zombieae, is harder to spot: The little black spots “look like fleas,” according to Araújo.

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

“In some cases, it first castrates Ophiocordyceps (the zombie-making fungus) so it can’t shoot spores anymore, and then it grows and then consumes the entire fungus.” Since Niveomyces and Torrubiellomyces are so new to science, it’s not yet clear how much of an effect they have on zombie ant fungal populations in general.

One of the new fungi, Niveomyces coronatus, causes the white coating on the zombie ant fungus.

These new genera are the first parasites officially described as infecting the zombie ant fungus, but the researchers suspect there may be others out there. “I think it is more common than we think. Parasitism is a super lucrative type of lifestyle,” said the study’s lead author, Dr. Charissa de Bekker, an assistant professor at Utrecht University in the Netherlands. “It could be the most dominant lifestyle on the planet.”

Furthermore, he said, parasites in general and parasitic fungi in particular are poorly studied. “The fact that we had to invoke two new genera tells you 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 did not participate in the study.

“Ophiocordyceps has basically evolved over evolutionary time into an expert neuroscientist. It knows exactly which buttons to push and how to make the ant do what it wants,” he said. “By studying how to solve this problem, we can get a sense of our more general goal of trying to understand how brains work or how they produce behavior.”

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