U.S. ants defending against their invading Argentine counterparts may have found a deterrent to the fast-spreading colonies: weapons of mass destruction.
Stanford University sophomores conducted a research project that suggests that winter ants have been using a form of chemical warfare – manufacturing a poison in a gland in their abdomens – to stop Argentine ants in their tracks, according to ScienceDaily.
"This is the first well-documented case where a native species is successfully resisting the Argentine ant," Deborah M. Gordon, a biology professor, said in a ScienceDaily article based on a Stanford press release.
Argentine ants, native to – you guessed it – Argentina and other parts of South America, are pervasive in hot climates but have increasingly invaded colder climes.
In 2009 the BBC reported that supercolonies of the species in Europe, Japan and the United States actually had the same parentage, thus forming one intercontinental megacolony.
"If you live in a Mediterranean climate, the Argentine ant is the ant in your kitchen," Gordon said. "These ants, wherever they become established, wipe out all the native ants."
But they're being repelled by winter ants tired of running, the Stanford project has found.
The Stanford project began four years ago as students began observing ant mounds on campus. “One day it was just winter ants going about their business foraging for food and making trails – just typical ant behavior," said Leah Kuritzky, a Stanford student involved with the project. "The next day we came back and the ground was littered with Argentine ants. There were dead ants all around and there was a lot of fighting around the nest entrances."
"It turns out the winter ants use the secretion only when they are really overwhelmed, so it is probably energetically very expensive for the winter ant to manufacture and use this stuff," Gordon said.
Gordon said cooler weather in the region may also be contributing to the demise of the Argentine ants.