Across the southeastern United States a battle is raging -- ant against ant.
On one side are the dreaded fire ants, armed with a venom that is painful to humans and often fatal to competing insects.
On the other side are the tawny crazy ants -- smaller, stinger-less, but equipped with a secret weapon that allows them to defeat the fire ants time and time again.
As scientists have recently discovered, the tawny crazy ants can secrete a chemical antidote to the fire ants’ poison that is also a venom itself. And though this venom doesn’t kill the fire ants, it appears to force them into retreat.
“As this plays out, unless something new and different happens, crazy ants are going to displace fire ants from much of the southeastern U.S. and become the new ecologically dominant invasive ant species," Edward LeBrun, a researcher at the Fire Ant Research and Management Project at the University of Texas at Austin, said in a statement.
Fire ants and tawny crazy ants are native to South America, where their battle may have raged for thousands of years. Fire ants arrived in the United States first, sometime in the 1930s. The crazy ants didn’t start to show up until the early 2000s.
LeBrun first discovered the tawny crazy ants’ detoxification behavior while watching them battle fire ants over a cricket carcass he put out as bait. The fire ants swarmed the bait, and then the crazy ants entered the fray.
At first LeBrun thought the crazy ants were doing a kamikaze maneuver, but then he noticed crazy ants that had been sprayed with the venom of the fire ants moving off to the side to perform an elaborate grooming behavior.
As you can see in the video above, the crazy ant secretes a substance out of the tip of its abdomen, transfers it to its mouth, and then starts rubbing itself all over.
“They just kept doing it, and then I was like, ‘Are they trying to detox?’ It was very exciting,” LeBrun said.
Later, in lab experiments LeBrun and his colleagues discovered that the antidote secreted by the tawny crazy ants is the chemical formic acid, and it appears to be very effective.
When crazy ants were prevented from secreting the antidote after researchers brushed a bit of nail polish on their abdomens, 48% of them died when exposed to fire ants. When they were allowed to secrete the antidote, 98% survived.
The research was published in the journal Science Express.
The scientists have not yet worked out exactly how the formic acid protects the crazy ants from the fire ant venom, but LeBrun said he’s working on it. He also added that it was not yet clear that the crazy ants would completely displace the fire ants or whether they may be able to coexist.
Tawny crazy ants may seem preferable to fire ants because they don’t sting, but, LeBrun says, they can cause even more damage than the stinging ants.
“They cause a lot of ecological harm and environmental harm,” he said.