Natural fungus found to crash tawny crazy ant populations


March 29, 2022

crazy ant PHOTO: Dr. Blake Layton

Tawny crazy ant workers with brood. PHOTO: DR. BLAKE LAYTON

The journal Proceedings of the National Academy of Sciences has published an article by researchers from The University of Texas at Austin that demonstrates how a naturally occurring fungus can crush local populations of tawny crazy ants (Nylanderia fulva).

“I think it has a lot of potential for the protection of sensitive habitats with endangered species or areas of high conservation value,” Dr. Edward LeBrun, a research scientist with the Texas Invasive Species Research Program at Brackenridge Field Laboratory and lead author of the study, said in a news release.

In some parts of Texas, the release notes, “homes have been overrun by ants that swarm breaker boxes, AC units, sewage pumps and other electrical devices, causing shorts and other damage. Natives of South America, tawny crazy ants have raised alarm bells as they’ve spread across the southeastern U.S. during the past 20 years. The idea for using the fungal pathogen came from observing wild populations of (tawny) crazy ants becoming infected and collapsing without human intervention.

“About eight years ago, (Drs. Rob) Plowes and LeBrun were studying (tawny) crazy ants collected in Florida when they noticed some had abdomens swollen with fat. When they looked inside their bodies, they found spores from a microsporidian, a group of fungal pathogens — a species new to science. Microsporidian pathogens commonly hijack an insect’s fat cells and turn them into spore factories.”

Dr. Plowes and another co-author, Dr. Lawrence Gilbert, are from The University of Texas at Austin’s Brackenridge Field Laboratory. A fourth author, Dr. Melissa Jones, is formerly of the Texas Parks and Wildlife Department.

“It’s not clear where the pathogen came from, perhaps from the tawny crazy ants’ native range in South America or from another insect, but (Dr.) LeBrun and his colleagues started finding the pathogen in crazy ants at sites across Texas,” the news release reports. “Observing 15 local populations for eight years, the team found that every population that harbored the pathogen declined — and 62 percent of these populations disappeared entirely.”

“You don’t expect a pathogen to lead to the extinction of a population,” Dr. LeBrun said. “An infected population normally goes through boom-and-bust cycles as the frequency of infection waxes and wanes.”

According to the news release, Dr. LeBrun theorizes that “perhaps the colonies collapsed because the pathogen shortens the lifespan of worker ants, making it hard for a population to survive through winter.

“Whatever the reason, it seems to be a (tawny) crazy ants-only problem. Unrelated to other microsporidia that infect ants, the pathogen appears to leave native ants and other arthropods unharmed. The researchers plan to test their new biocontrol approach this spring in other sensitive Texas habitats infested with (tawny) crazy ants.”


About the Author

Heather Gooch

Heather Gooch is the editor-in-chief for PMP magazine. She can be reached at or 330-321-9754.

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