“Zombie ant” fungi infected with their own parasites
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All over the world, a parasitic fungus is turning ants into ‘zombies’.
The fungus is like something out of a horror movie: the organism hijacks the body and brain of its host ant, mind-controlling it to abandon its nest and climb a nearby tree.
There, the infected ant clamps its jaws around a leaf hanging above the forest floor and dies in a few days as the fungus digests it. Penetrating through the body of its host, the fungus then sends out a shower of spores to infect the next generation of ant prey.
Scientifically categorized in the genus Ophiocordyceps, more than two dozen species of zombie ant mushroom inhabit the globe, including Florida, Brazil and Japan; scientists suspect that each of the dozens of ant species affected has its own specialized strain of Ophiocordyceps.
So far, scientists have understood the molecular mechanism of the parasitic interaction between the fungus and the ant, which forms the basis of the behavioral manipulation, according to 2020 survey. However, exactly how these parasites systematically act is poorly understood.
Now scientists have revealed that ant-attacking fungus is infected with its own fungal parasites, which could help control ant zombification, according to a new study.
Dr. João Araujo, assistant curator of mycology at the New York Botanical Garden, has been scouring the rainforest in search of zombie ants for more than a decade. Over the years, he kept noticing something strange: a fuzzy white mushroom growing on top of the zombie ant mushroom.
Other scientists have noticed the mysterious fungus for decades, but Araujo and his colleagues decided to become the first scientists to systematically dig into the question, focusing on a strain of zombie ants from Florida. The researchers described the physical structure of the fungus growing on the zombie ant fungus and sequenced its DNA in study published Nov. 9 in the journal Persoonia.
In this way, the team discovered two new genera of fungi previously unknown to science.
“We found that there are two different lineages of fungus, new lineages of fungus, infecting a type of zombie ant fungus in Florida,” said Araujo, the study’s lead author.
Each of the two newly discovered mushrooms belongs to its own genus. One of the new fungi, Niveomyces coronatus, is responsible for the fuzzy white coating on the zombie ant fungus – a component of its name (‘niveo’) comes from the Latin for ‘snowy’. The second new fungus, Torrubiellomyces zombiae, is harder to spot: the tiny black spots “look like fleas,” according to Araujo.
The fungi attacking the zombie ant fungus do not in turn zombify their host, but feed on its tissues and appear to cause it harm. “Every time we see these new genera that we’ve described growing on the sponge, the sponge looks pretty broken up, really engulfed by this other sponge,” Araujo said.
“In some cases, it first castrates the Ophiocordyceps (the zombie-creating fungus) so it can no longer shoot the spores, and then it grows and then engulfs the entire fungus.” Because Niveomyces and Torrubiellomyces are so new to science, it’s not yet clear what is their effect on zombie ant populations in general.
These new genera are the first parasites officially described as infecting the fungus zombie ants, but researchers suspect there may be others. “I think it’s more common than we think. Parasitism is a super-lucrative way of life,” said lead study author Dr. Harissa de Becker, assistant professor at Utrecht University in the Netherlands. “It may be the most dominant way of life on the planet.”
What’s more, she said, parasites in general and parasitic fungi in particular are poorly studied. “The fact that we had to call two new genera tells you how little we know about this part of the fungal tree of life,” de Becker said.
By deepening our understanding of the zombie ant fungus, the new research may have applications that go beyond the study of fungi, said Dr. Carolyn Elya, a postdoctoral fellow in organismal and evolutionary biology at Harvard University. She did not participate in the study.
“Ophiocordyceps basically evolved over evolutionary time into an expert neurologist. It knows exactly which buttons to push and how to make the ant do what it wants,” she said. “By studying how it’s figured out how to solve this problem, we can have insight into our more general goal of trying to understand how brains work or produce behavior.”