Queen-Ant-Killing ‘Zombie Fungus’ Discovered By Undergrad

D-myrmecophila-fuzz
A rare ant-infecting fungus known as Desmidiospora myrmecophila. The infected queen ant can't be seen beneath the thick fungal covering. Stephen Saltamachia

While hanging out in a forest in southwestern Louisiana, Stephen Saltamachia found a carpenter ant queen acting strangely: It was wandering around in broad daylight.

No big deal, right? Well, not really. Queens are rarely found outside of the nest. A born naturalist, Saltamachia suspected that the ant might be parasitized by a brain-manipulating pathogen often called “zombie fungus,” which causes infected insects to behave abnormally.

So he sterilized the beleaguered queen and put it in a petri dish to see if anything strange might issue forth from its body. And indeed, something wicked that way came.

The dead insect gave rise to a vigorous, furry fungus that sprouted from its dead body like moldering cotton candy. Upon closer inspection under the microscope, it looked like nothing Saltamachia had ever seen before. Although just a senior at the University of Louisiana-Lafayette, he pored through reams of fungal research and reached out to mycologists (fungi experts) on ResearchGate, a social network of sorts for scientists.

Turns out, it was an extremely rare type of parasitic fungi that had been “missed by mycologists and entomologists” throughout the United States for nearly a century, says David Hughes, a researcher at Pennsylvania State University who specializes in zombie ant fungi and who has corresponded with Saltamachia via email—but not met in person.

Called Desmidiospora myrmecophila in the literature, this furry fungus was discovered in the 1800s and has only been mentioned in studies a handful of times, with the last major citation in the 1920s.

Hughes says he is going to help Saltamachia sequence the species’s genes, to find out exactly where it fits in the fungi family tree. The Penn State researcher says it is likely in the same genus, or taxonomic grouping, as the more well-known “zombie fungus,” known as Ophiocordyceps. If that is indeed the case, the species will have to be renamed, since the two are not currently included in the same genus.

rare-fungus-clover-shaped-spore The chlamydospore, a thick-walled structure involved in fungal survival and reproduction, resembles a clover. Stephen Saltamachia

Fungi in this group infects ants and other insects and often control their behavior to maximize their potential to spread—before ultimately killing the animal. For example, one such fungus infects ants and forces them to climb high up vegetation before perishing and giving rise to horn-like fungal growths, thus allowing the species’s spores to spread farther than they would if released closer to the ground.

Saltamachia says he identified the fungus in part by the distinctive shape of its chlamydospore, a thick-walled structure involved in fungal survival and reproduction, that looks something like a brain-shaped clover.

One of the most unique aspects of the fungus is that it only appears to infect queen ants, Hughes says. It’s unclear exactly how it does that, and it’s unknown how the fungus affects queens’ behavior other than perhaps influencing them to leave their nest and killing them, he adds.

Saltamachia found the fungus in the Acadiana Park Nature Station, a forested area outside Lafayette, where he has worked for nearly a decade and now teaches visitors about native flora and fauna.

“Even though I’ve been working there 10 years, you find something new about every day,” he says. “I’ve always loved that about nature.”

Besides sequencing the fungus, Saltamachia is also currently occupied with finishing his undergraduate microbiology studies and hopefully applying to graduate school.

“Last semester I spent way too much time thinking about fungus and not school work,” he adds.  

rare-fungus-stalks The fungus also possesses these stalk-like structures. Stephen Saltamachia