AUSTIN (KXAN) — University of Texas at Austin scientists may have found a way to stop a violent invasive ant species that has been ravaging the state for decades.
UT said tawny crazy ants have been known to swarm breaker boxes on homes, air conditioning units, sewage pumps and other electrical devices in some parts of Texas. They’re originally from South America but have been spreading across the southeastern part of the country for the past two decades.
The bullies of the insect kingdom
On the school yard of insect high, there are the preppy fire ants, with their puka shell necklaces and stinging barbs. The goth carpenter ants who only come out at night. Black harvester ants, the hippies who like to be outdoors and avoid humans. Then there are the bullies: the tawny crazy ants.
“They’ll eliminate all the co-occurring native ants that are bigger than them, a lot of the insect diversity,” said Edward LeBrun, a research scientist at the University of Texas who’s been studying crazy ants for a decade.
A crazy ant epidemic
Lebrun said that in 2013, they discovered a microsporidium that attacks the crazy ants. The microsporidium acts sort of like a fungus, releasing tiny spores that the ants then breathe in.
“The spore actually fires out a harpoon like structure,” Lebrun said. “It’s like a long tube with a sharp tip at the end. And that punctures the cell wall of the host.” The spore then injects its own DNA into the ant’s fat cells. The DNA then takes over the cells machinery, forcing it produce more fungal spores.
LeBrun and others at the Brackenridge Field Laboratory first observed this happening in crazy ants collected from Florida. Before it was found in crazy ants at sites across Texas.
A team observed 15 populations in Texas for eight years and found every population stricken by the pathogen declined, and 62% of them disappeared altogether. LeBrun said the spore “shortens the lifespan of the workers and it reduces the amount of brood and how much of that brood successfully develops the larvae, ant larvae to adult ants.”
Testing a crazy ant solution
This specific pathogen only affects crazy ants in this way. Native ants and other arthropods seemed to be unharmed, according to UT, so researchers thought it was the perfect solution to the crazy ants problem.
The Brackenridge Field Laboratory team tested out their theory in 2016 by deploying the pathogen at Estero Llano Grande State Park, which is located in Weslaco. UT said the park was plagued by crazy ants, and it was losing wildlife like scorpions, snakes, lizards, rabbits and birds to the insects. “Over time, infected populations declined quite dramatically,” LeBrun said.
For the test, the team used crazy ants from other sites that already had microsporidian, and put them near the nesting sites of crazy ants in the park. UT said the team then used hot dogs to attract the local ants and merge the two groups.
In the first year of the experiment, UT said the pathogen spread to the entire crazy ant population in Estero. Within two years, the population numbers took a nosedive. Today, crazy ants are “nonexistent” in the park, and native species are bouncing back.
Because of the way the microsporidium has spread, LeBrun says it is considered a type of epidemic called a epizootic. This is an epidemic in the animal kingdom.
Researchers have also depleted a second crazy ant community in the Convict Hill area of Austin. They plan to test this method more this spring at other Texas sites, researchers said.
Is this the solution to the crazy ant problem?
LeBrun says that using this fungus like a pesticide is unlikely. “We’re only able to transmit it by finding live infected workers and introducing them into uninfected colonies.” LeBrun says this is costly and time consuming.
The good news is that his fungus is spreading on its own. “If you happen to be an environment that’s invaded by these ants, this disease is also moving around naturally on its own. So the ant population you’re living in has a lifespan, and it won’t be there forever.”