By: Jackson Griffith
Clark Pest Control Corporate
Imagine a giant, thriving city along the coastal half of California that stretches over 600 miles, linked by subterranean tunnels from San Diego in the south all the way to Ukiah 115 miles north of San Francisco, with a population of billions. A future scene from a dystopian science-fiction narrative?
No. According to some scientists, that city exists today. However, it’s populated by ants, not humans – specifically, Argentine ants (Linepithema humile), an invasive species thought to have entered America at New Orleans on coffee ships from South America in the late 19th century. L. humile then spread westward to California via railroads and other modes of transportation.
What makes Argentine ants different from most other ant species is that individual ants hatched from one queen’s eggs will cooperate with ants from another queen. Most ant species will fight ants from another colony, because each colony’s ants carry a unique chemical marker that signals they are family to ants from their own colony, but an enemy to same-species ants from a neighboring colony. However, Argentine ants from two different queens won’t have such conflict with each another, because their chemical markers are similar enough for a match, and so they and their sisters – worker ants are invariably female – will team up to drive out whatever native ant species is still crawling about the neighborhood.
These large cities of Argentine ants were described by a team led by biologist Neil D. Tsutsui, then at University of California San Diego, as supercolonies. Three have been identified: in coastal California, in Europe along the Mediterranean coast, and in western Honshu, the largest and most populous island of Japan. The former two have Mediterranean climates; western Honshu is subtropical. And even those are related: When researchers mixed ants from the different supercolonies together in a laboratory setting, they didn’t square off for battle, but got along like long-lost sisters.
Not all scientists agree with the concept of a supercolony, however. At Stanford University, researchers disagreed that the California supercolony is more diverse genetically, and ants around the state don’t seem to spring from a common set of parents; what appears to be a supercolony is really a large grid of interlinked colonies. In either scenario, though, the ants would rather cooperate against a common enemy than fight among themselves. We could learn a lot from Argentine ants.
In California, where one in every four ant infestations reported by pest management professionals involves Argentine ants, it means that if you’re experiencing an ant problem at home, there’s a 25-percent likelihood that L. humile is at cause. In many areas, that likelihood jumps to 100 percent. Your Clark professional will be able to identify the species of ant that’s giving you trouble, and then use the principles of integrated pest management (IPM) to restore your home to a pest-free state.