December 3, 2022

The "zombie ant" fungus is infected with its own parasite

The “zombie ant” fungus is infected with its own parasite

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

The mushroom is like something out of a horror movie: the organism hijacks the body and mind of its ant host, brain-wielding it to abandon its nest and climb a nearby tree.

There, the infected ant clenches its jaws around a leaf, overhanging the forest floor, and dies within days as the fungus digests it. The fungus explodes in its host’s body, then sends out a shower of spores to infect the next generation of ant prey.

Scientifically classified in the genus Ophiocordyceps, more than twenty species of zombie ant mushrooms are common in the world, including Florida, Brazil and Japan; Scientists suspect that each of the dozens of infected ant species has its own Ophiocordyceps lineage.

So far, scientists have discovered the molecular mechanism of parasitic interaction between fungus and ants that forms the basis of behavioral manipulation, according to Study 2020. How exactly these parasites function systemically, however, is poorly understood.

Scientists have now revealed that the fungi that attack ants are infected with their own fungal parasites, which may help keep the ants in check, according to a new study.

Dr. Joao Araujo, 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 mysterious white fungus growing on top of the zombie ant mushroom.

Other scientists have observed the mysterious fungus for decades, but Araujo and his colleagues decided to become the first scientists to systematically delve into the issue, by focusing on a strain of zombie ants from Florida. The researchers described the physical composition of the fungus that grows on top of the zombie ant fungus and sequenced their DNA in a study A study published November 9 in the journal Persononia.

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

“We realized there were two different strains of fungus, new strains of fungus, infecting one species of zombie ant fungus in Florida,” said Araujo, lead author of the study.

Each newly discovered type of fungus belongs to its own genus. One new fungus, Niveomyces cornatus, is responsible for the fuzzy white coating on the zombie ant fungus—one component of its name (“niveo”) comes from the Latin for “snowy.” The second new fungus, Torrubiellomyces zombiae, is harder to spot: The little black dots “look like fleas,” according to Araujo.

The fungus that attacks the zombie ant fungus does not in turn kill its host, but rather feeds on its tissues and appears to cause damage to it. “Every time we see these new genera we’ve described growing on mushrooms, it seems like the fungus has been beaten down, really consumed by this other fungus,” Araujo said.

“In some cases, Ophiocordyceps (the mushroom that makes zombies) castrates first, so it can’t shoot spores anymore, then it grows and then consumes the entire fungus.” Because Niveomyces and Torrubiellomyces are so new to science, it’s not yet clear how much they affect zombie ant fungus populations in general.

One of the new fungi, Niveomyces cornatus, is causing 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. “I think it’s more common than we think. Parasitism is a very profitable type of lifestyle,” said senior study author Dr. Carissa De Becker, assistant professor at Utrecht University in the Netherlands. “It may be the most widespread way of life on the planet.”

What’s more, she said, parasites in general and parasitic fungi in particular have not been well studied. “The fact that we had to call two new genus tells you how little we know about this part of the fungal tree of life,” said de Becker.

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

“Ophiocordyceps has basically become over evolutionary time an expert neuroscientist. It knows exactly what buttons to press and how to get the ant to do what it wants.” By studying how we figure out how to solve this problem, we can gain insight into our overall goal of trying to understand How brains work or produce behaviour.