Argentine ants protect agricultural pests in California

Argentine ants are impacting citrus groves and vineyards in California by protecting agricultural pests from natural predators. Originally from South America, these ants have established a massive, interconnected supercolony across a vast stretch of the California coast, from San Diego to Ukiah.

Researchers have found that the ants form a cooperative network of nests rather than fighting one another, a result of genetic bottlenecks in the introduced population. This supercolony behavior allows the ants to defend sap-sucking insects—such as aphids, mealybugs, and whiteflies—against the parasites and predators that would typically control their numbers. By protecting these pests in exchange for honeydew, the ants increase pest pressure and complicate biological control efforts for farmers.