Org is looking for news and content to keep this website fresh. Ant Spread Evelyn Strauss Argentine ants have become common pests worldwide, raiding kitchens from San Francisco to Johannesburg to cart away crumbs of chocolate cake and soetkoekies. Most ants defend their territory against other colonies, particularly those of the same species. But Argentine ants far from their South American home generally don't fight each other, although they still attack other ants. In lab studies, the researchers have shown that pairs of Argentine ant colonies that don't fight reach higher population numbers than pairs of warring colonies, possibly because they waste less time and energy.
Argentine ants show their fighting mettle by attacking a harvester ant.
Although most Argentine ants in Southern California don't attack each other, Andrew Suarez, a graduate student in Case's lab, found some that did. Taking advantage of this natural variation, the group reared pairs of colonies, both containing either the aggressive or nonaggressive ants, in a setup that gave the two colonies access via plastic tubing to a shared area that contained food. The warlike colonies started battling immediately, and many ants died, says postdoc David Holway, a community ecologist in Case's lab. After a few weeks, workers stationed themselves at the openings to the plastic tubes as if to prevent incursions from members of the other nest. Furthermore, in the peaceful setting, the ants foraged for food more actively.