HOW ANTS EFFECTIVELY FIGHT PATHOGENS
Auburn University Assistant Professor of Entomology Clint Penick and a team of graduate students may have found that ants are ahead of humans in the development of antibiotics. He worked with Katy Chon, graduating master’s student from Kennesaw State University, and Darmon Kahvazadeh, Auburn entomology and plant pathology graduate research assistant, on research that was recently published in the Biological Journal of the Linnaean Society, a direct descendant of the oldest biological journal in the world, which published the epoch-making papers on evolution by Darwin and Wallace.
“In our study, we tested how ants use antibiotic compounds to fight off pathogens and asked why their chemical defenses remain effective over evolutionary time,” Penick said. “Humans have relied on antibiotics for less than a century, yet many pathogens have already evolved resistance, giving rise to ‘superbugs’ that are difficult to treat.”
“Ants, by contrast, have been using antibiotics for tens of millions of years, and they might hold the key to using these powerful drugs more wisely.”
The team looked at just six ant species, all found easily in the Southeastern United States.
“These are the ants that live in our backyards and live on college campuses,” Penick said. “And yet some of the most powerful antibiotics we found come from ants we typically think of as pests, like fire ants.”
In scientific terms, an antibiotic is something produced by a bacterium that kills other bacteria. But generally, an antibiotic is understood as anything that kills microbes, and this is what human medicine scientists have been doing since the 1950s.
“And yet we’re dealing with these massive superbugs that are difficult to control, and we’re losing the race,” Penick said. “They’re evolving resistance faster than we’re developing antibiotics. So, how have ants been able to do it for tens of millions of years?”
Penick and his team have two hypotheses.
“One is that they might produce multiple types of antibiotics and different types of chemical compounds,” he said. “It’s just like if you go to the doctor and they try one. If it’s not working, they’re going to try another one. Maybe ants have different medicines in their medicine cabinet, if you will. If a strain is resistant to one thing, we’ll try another — we found evidence that ants have the capability to do the same thing.”
Another possibility came from the researchers asking if ants can produce things that are targeted to specific microbes — one of science’s biggest challenges today.
“If we just dump antimicrobials or antibiotics into systems that kill everything, you’re not only killing your target pathogen but you’re killing all these other things,” Penick explained. “And by doing that, you’re helping breed these resistant genes and non-target populations. Because microbes can just swap genes between species, it accelerates antibiotic resistance.”
“This is something that people are really interested in in human medicine — figuring out more targeted antibiotics.”
“If it’s strep, they’re going to treat with a specific antibiotic that’s focused on strep,” he said. “And if it’s not strep, then it usually means it’s a viral infection, which will resolve on its own. We’re wondering if ants are doing the same thing.”
In human medicine, this kind of targeted approach is especially important because broad-spectrum antibiotics can disrupt the body’s natural balance of microbes, including those that make up the gut microbiome. That disruption can lead to common side effects like stomach upset or secondary infections — and it can also accelerate antibiotic resistance.
“If we just dump antimicrobials or antibiotics into systems that kill everything, we’re not only killing our target pathogens but also beneficial microbes,” Penick said. “And that can actually accelerate antibiotic resistance, because microbes can swap resistance genes.”
“This is something human medicine is very interested in — figuring out how to create more targeted antibiotics.”
The team found evidence that, at the very least, ants are producing some that are specific to fungi, some that are specific to gram-negative and some that are gram-positive bacteria.
“So, it seems like ants are producing more targeted compounds, just like we’re doing,” Penick said. “We could guess they might be doing so, but we don’t really know now.”
While not the primary focus of the paper, the team found that nearly all of the ant species tested killed an emerging human superbug — Candida auris. This pathogen has been spreading in hospitals with few options for control, yet ant extracts were highly effective against it.
The next step is to look at what types of compounds ants are producing and how they’re using them.
“It could help inform our own practices or potentially we could discover new compounds that have mathematical importance,” Penick said. “Our findings suggest that ants could represent a vast and largely untapped source of new antibiotics, including ones capable of combating today’s most dangerous drug-resistant infections.”