But introducing more unwanted ants into California is not a solution, say Gordon and her colleagues, arguing that there are major flaws in the supercolony theory.
"There's a perception out there in the public eye that Argentine ants cover this wide, uninterrupted swath from San Diego to San Francisco," said postdoctoral fellow Krista K. Ingram. "But we've found that there are breaks in their distribution and barriers they do not cross."
In a study published in the journal Ecology last November, Ingram and Gordon analyzed the DNA of 768 ants collected from 48 nests in and around Stanford's Jasper Ridge Biological Preserve, a 1,200-acre research site located in the foothills above the main campus. The preserve is bounded by Sand Hill Road and the Stanford Linear Accelerator Center (SLAC) - two imposing barriers, from an ant's point of view. The SLAC facility is 1.9 miles long, 30 feet tall and 45 feet deep - a particularly formidable obstacle for an insect only an eighth of an inch long.
Using microsatellite data, Ingram and Gordon found obvious genetic differences between nests located inside the preserve and those on the opposite side of SLAC and Sand Hill Road, less than 300 feet away. These results contradict the UCSD study, which found genetic similarity up and down the California coast.
"How can they be genetically homogenous across wide, wide scales, when they're not even genetically homogenous across hundreds of meters?" asked Nicole E. Heller, a graduate student in the Gordon lab who has conducted field research in Argentina and California.