A new type of ant species was noticed several years ago by staffers at the park. The tawny crazy ants were so aggressive that they were driving birds out of their nest and occasionally swarming over visitors who paused to sit on a trail. Populations of other native species like scorpions, snakes, tarantulas, and lizards declined, while rabbits were blinded by the ants' venom.
Ed LeBrun is a Biologist at the University of Texas at Austin. He said that the park had a crazy ant invasion, with rivers of ants going up and down every tree. Crazy ants have spread quickly through every state on the Gulf Coast. The EPA has approved the use of an anti-termite agent called fipronil, which is restricted, because the usual ant-bait traps and over-the-counter pesticides have failed. A less toxic control strategy would be better.
LeBrun has worked on fire ants, which have been a problem in the region. He has been researching sustainable control strategies based on crazy ants in the wild for the last few years. A new paper by LeBrun and his colleagues states that a specific type of fungus can wipe out crazy ant colonies while leaving other native species alone.
The tawny crazy ants were originally from South America. They are also known as crazy ants. The ants do not build central mounds or nest. Colonies make their homes under stones, in rotting logs, or in a hole in the ground. Crazy ant colonies have multiple queens.
AdvertisementCrazy ants are attracted to electrical equipment. They can chew through insulation and wiring. A chicken can be killed by a swarm of crazy ants, and cattle can be killed by swarms of crazy ants. Some homeowners in the Lone Star State were cleaning up dustpans full of dead crazy ants on a daily basis.
Crazy ants excrete formic acid, which can be used as a venom, but they don't have the painful bite of fire ants. Scientists discovered that crazy ants could survive exposure to fire ant venom 98 percent of the time by using their own formic acid. Crazy ants only had a 48 percent survival rate when their ducts were blocked.
LeBrun and Rob Plowes of the Brackenridge Field Laboratory had conducted research on a group of crazy ants in Florida. The ants had swollen abdomens. LeBrun and Plowes found that the bodies had parasites in them. The researchers had seen similar symptoms in fire ants when they were bitten by other kinds of microsporidia. The type of microsporidium affecting the crazy ants was a new species, suggesting it might be able to leave other species alone.
This was the first time that LeBrun had been able to find the crazy ants armor. He and his co-authors have been studying this new type of microsporidia to learn more about how it spreads. The crazy ant colonies in Texas were monitored for eight years for signs of infections.
AdvertisementThe scientists found that the population of crazy ant fell over the winter and that 62 percent of the population was wiped out. That is unusual since there is a boom and bust cycle associated with the spread of pathogens. The shortened life spans of worker ants make it harder for colonies to gather enough resources to survive the winter.
LeBrun and his team collected crazy ants from other regions and put them in nest boxes. The researchers used hot dogs to lure the two populations together. The result was an increase in the number of infections at both sites.
The area is free of crazy ants and native species have begun to return. LeBrun and his team plan to expand their biocontrol method to other Texas habitats this spring after they eradicated a crazy ant outbreak at a second site.
LeBrun said that it has a lot of potential for the protection of sensitive habitats. It is not possible to predict how long it will take for the lightning bolt to hit and the pathogen to enter a population of ants. It means that these populations appear to have a life span.
PNAS was published in 2022. About DOIs is 10.1073/pnas.
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