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A glob of 99 million-year-old amber has preserved an ancient fly in horror show fashion: with the mushroom-like fruiting body of zombie fungus bursting forth from its head.
The insect, along with a second specimen of a young ant infected with a similar fungus, are two of the oldest examples of a bizarre natural phenomenon that involves fungal parasites hijacking the bodies of their hosts before ultimately killing them.
“Amber gives us this opportunity to visualize the ancient ecological relationships preserved in fossils,” said Yuhui Zhuang, a doctoral student at the Institute of Paleontology at Yunnan University in southwestern China.
“Overall, these two fossils are very rare, at least among the tens of thousands of amber specimens we’ve seen, and only a few have preserved the symbiotic relationship between fungi and insects,” added Zhuang, the lead author of a study on the fossils published June 11 in the journal Proceedings of the Royal Society B: Biological Sciences.
Zhuang and his colleagues named two previously unknown species of ancient fungi of the genus Ophiocordyceps from their research on the amber, which involved using optical microscopes to study the tiny pieces of amber and micro-computed tomography to make 3D images of the fungi-infected insects. They found the first, named Paleoophiocordyceps gerontoformicae, on the ant and the second, Paleoophiocordyceps ironomyiae, on the fly.
Some Ophiocordyceps species that prey on ant species today are known as “zombie-ant fungi” because the fungal parasite can manipulate the behavior of its hosts for its own benefit. The phenomenon inspired the video game behind the HBO TV show “The Last of Us.” HBO shares a parent company, Warner Bros. Discovery, with CNN.
“The discovery of these two fossils suggests that terrestrial ecosystems were already very complex, and that Ophiocordyceps, in particular, may have begun to act as “predators” of insects in the Cretaceous period, regulating the populations of certain groups,” Zhuang said via email.
Zombie fungi then and now
Today, parasitic fungi, also known as entomopathogenic fungi, infect a wide range of insect groups, including ants, flies, spiders, cicadas and beetles, according to London’s Natural History Museum.
In the case of carpenter ants, the spore of the Ophiocordyceps fungus lands on the head of an ant, enters its brain through a weak area in the insect’s exoskeleton and takes control of the ant to facilitate its spread, said Conrad Labandeira, senior scientist and curator of fossil arthropods at the Smithsonian Museum of Natural History in Washington, DC, who wasn’t involved in the study.
Paleoophiocordyceps likely zombified its hosts in similar ways, according to Labandeira.
“It appears that ants, for some reason, were targeted early for zombification, and currently are the major recipients of this parasitoid fungus,” Labandeira said. He added that flies are only rarely affected by these parasitic fungi today, making a fossilized example particularly interesting.
The species of fungus that infected the prehistoric ant may be an ancestor of zombie-ant fungi, and thus likely controlled its host’s body in similar ways, said study coauthor João Araújo, mycology curator and assistant professor at the Danish Natural History Museum. Very few specimens of ancient parasitic fungi have been discovered, so little is known about their evolution.
The two insects were likely killed by the fungi before getting trapped in the sticky tree resin that ultimately forms amber, said Araújo, noting that most entomopathogenic fungi kill their hosts to produce the fruiting body.
This lost parasite diversity had a significant role in shaping the planet we live on today, said Phil Barden, an associate professor at New Jersey Institute of Technology’s department of biological sciences, who has worked on amber fossils.
“Even as we find a remarkable diversity of organisms entombed in amber, it’s important to remember that we really do only capture the smallest glimpse. For any given fossil ant or beetle, we can imagine all of the parasites, fungus, and bacteria that such insects support,” Barden, who wasn’t involved in the new study, said via email.
It was “fascinating to see some of the strangeness of the natural world that we see today was also present at the height of the age of the dinosaurs,” said study coauthor Edmund Jarzembowski, a professor and associate scientist at London’s Natural History Museum.
The fossil is the latest to emerge from Myanmar’s rich amber fields.
While amber fossils have been some of paleontology’s most exciting finds in recent years, ethical concerns about the provenance of amber from the civil war-torn region have emerged.
Zhuang said the fossils were sourced from Myanmar’s amber markets. The study noted that the specimens were acquired before 2017 and, to the authors’ knowledge, were not involved in armed conflict or ethnic strife.