Tawny crazy ant
Tawny crazy ants have invaded Texas. UTA Brackenridge Field Laboratory

In the Texas underworld of arthropods, there is a new villain in town—the tawny crazy ant. The invasive species from South America devours other ants, chases away snakes, lizards, and birds, and even blinds baby rabbits by spraying formic acid in their eyes. Nasty. With apparently no natural predator in their new environment to keep them at bay, the swarming invaders have formed massive super colonies—even interfering with the electronic devices of another dominant species. But a team of long-researching scientists at the University of Texas – Austin’s Brackenridge Field Laboratory may have found the powerful little dynamo’s kryptonite: fungus.

Invasive ants are nothing new in the United States. Argentine and black ants arrived more than a hundred years ago, only to be displaced by fire ants in the 1930s. Since the early 2000s, though, crazy ants, utilizing a novel application of chemical warfare, have rapidly expanded their range and are now displacing their stinging cousins. Scientists have been concerned that they may be unstoppable.

But eight years ago, while studying crazy ants in Florida, ecologists Edward LeBrun and Rob Plowes discovered a vulnerability. Mysteriously, some of the ants were carrying a previously unknown species of pathogenic fungus in their abdomens. Later, they encountered the same fungus in tawny crazy ants in Texas. After years of study, Lebrun, Plowes, Lawrence Gilbert of Brackenridge, and Melissa Jones, formerly of the Texas Parks and Wildlife Department, found that 62 percent of colonies that harbored the fungus eventually disappeared entirely. 

“You don’t expect a pathogen to lead to the extinction of a population,” Lebrun told UTNews. “An infected population normally goes through boom-and-bust cycles as the frequency of infection waxes and wanes.” But that wasn’t the only surprise. Lebrun and his team also discovered that the fungus did not seem to harm other ants or arthropods. 

In 2016, when a super colony of tawny crazy ants swarmed the Estero Llano Grande State Park in Weslaco, Lebrun got a call. “They had a crazy ant infestation, and it was apocalyptic—rivers of ants going up and down every tree,” LeBrun said. “I wasn’t really ready to start this as an experimental process, but it’s like, OK, let’s just give it a go.” Lebrun and his team planted fungus-infected ants in the colony and, today, the crazy ants have been eradicated from the park and native species are returning. After another successful eradication in Austin, the team plans to test their method this spring in other infested sites in Texas.

So, don’t worry, Texans. If a villainous horde of foreign arthropods is tormenting a neighborhood near you, there is an intrepid team of scientists—and a fungus—ready to defend you.

Lebrun and the team describe their work in a new study published in the journal, Proceedings of the National Academy of Sciences.