Stinging fire ants are no match for acid-covered crazy ants that have been waging chemical warfare to overrun parts of the American South.
That's the eye-catching – or stomach-turning – finding by researchers from the University of Texas at Austin, who published a new paper Thursday titled, “Chemical Warfare Among Invaders.”
Tawny crazy ants, named for their tan color and erratic movements, have been displacing colonies of fire ants in southern Texas and Florida by using a novel chemical defense, one that helps them heal stings from fire ants during battles.
“Upon being stung, crazy ants stand on their hind and middle legs, curl their modified abdomens underneath their bodies and begin grooming themselves with secreted formic acid,” a statement on the findings says. “This detoxification behavior allowed 98 percent of tawny crazy ants stung by fire ants to survive, compared to 48 percent without the detoxification behavior.”
A number of ant species use chemicals as weapons against one another, but what makes tawny crazy ants different is that they use their chemicals as a countermeasure.
“Where one ant uses its defensive chemistry to detoxify the venom of another ant, it is unique to our knowledge,” says Edward LeBrun, a researcher at the University of Texas who led the study. “It certainly opens up the question to look for it now.”
Both fire ants and tawny crazy ants hail from Argentina, Paraguay and southern Brazil. The researchers believe the crazy ants’ healing powers evolved there, where competition for resources is most fierce. The ants then brought this ability with them to the United States.
“They come north, and they meet their old enemies from South America, and they express this behavior,” LeBrun says.
Red ants have caused hundreds of millions of dollars in damage to agricultural crops and livestock, but they’ve been pushed out in recent years by tawny crazy ants, which often nest in electronics and have infested buildings, in particular, by the millions, news reports say.
“Once you have an invasion like this going on, and it’s getting out of cities and into nature, the next question becomes, ‘Well, how far are they going to go?’” LeBrun says. “One thing that could have limited them was competition with other species, like fire ants” – a competition that tawny crazy ants so far are decidedly winning.
“We don’t know what’s going to limit their range expansion,” LeBrun continues. “Most likely tolerance to drought, flooding, freezing, arid conditions, but we don’t yet know what those tolerances are for tawny crazy ants.”