This Fungal Pathogen Could Help Eliminate Destructive 'Crazy Ant' Invasions

Invasive tawny crazy ants are particularly destructive and can wreak havoc in the areas they invade. Researchers have now found a way to potentially control the species using a naturally occurring fungus.

Tawny crazy ants were first found in Houston in 2002. The species has since spread across the southeastern U.S., the University of Texas at Austin (UT Austin) noted in a news release.

In some parts of Texas, for instance, the ants can swarm inside houses and damage items such as electronics and breaker boxes, thereby causing damage. UT Austin has even described the ants as an "ecological wrecking ball," as they tend to outcompete and displace native insects and even other animals when they move into an area.

"These losses to biodiversity are greater than the damage done by imported fire ants that occupied these habitats before the crazy ant invasion," the Brackenridge Field Laboratory at UT Austin wrote.

In their study, published in the Proceedings of the National Academy of Sciences, a team of researchers looked at the effect of a fungal pathogen, Myrmecomorba nylanderiae, on the collapse of local tawny crazy ant populations.

The researchers started studying the pathogen years ago when they observed that some of the ants collected in Florida had rather swollen abdomens and their bodies actually had spores of a microsporidian, UT Austin noted. Microsporidian pathogens tend to hijack the insects' fat cells and "turn them into spore factories."

Over the following years, the researchers continued to find the pathogen in local ant populations and observed that the ones that had the pathogen saw population declines. In fact, among them, a whopping 62% even disappeared "entirely." At the same time, the pathogen left the other native creatures, including native ants, unharmed.

The researchers also got a chance to test the pathogen's potential as a biocontrol agent. In Estero Llano Grande State Park in Weslaco, Texas, for instance, the ants were found to be destroying other creatures, from insects to snakes and even birds.

"They had a crazy ant infestation, and it was apocalyptic, rivers of ants going up and down every tree," said study lead author Edward LeBrun, of UT Austin. "I wasn't really ready to start this as an experimental process, but it's like, OK, let's just give it a go."

The researchers introduced populations of infected ants in the area and merged them with the local populations. Sure enough, the tawny crazy ants have been eliminated, and native species are now returning to the once infested area. The researchers also eliminated the crazy ant population at another site.

Uninfected populations did not see a population decline during the period, noted the researchers.

According to them, it's possible that the populations collapsed because the infected worker ants didn't survive long enough "to bridge the gap created by normal, winter cessation of immature ant production."

The pathogen shows great potential as a possible means to control destructive tawny crazy ant infestations.

"This doesn't mean crazy ants will disappear," LeBrun said. "It's impossible to predict how long it will take for the lightning bolt to strike and the pathogen to infect any one crazy ant population. But it's a big relief because it means these populations appear to have a lifespan."

The researchers are set to continue testing the biocontrol method on other tawny crazy ant infestations in the spring. They are also looking into the potential of studying microsporidian pathogens on other invasive insects.