Using Behavioral Experimentation to Understand the Social Structure of the Little Fire Ant (Wasmannia auropunctata) in Florida

Abstract

Wasmannia auropunctata (LFA) is a small, yellow ant that is native to the Central and South America that has become a globally invasive species by acting as an agricultural pest in addition to being ecologically destructive in non-native regions. One trait thought to contribute to successful invasion of ants is unicoloniality, which is characterized by lack of aggression among workers and queens from different colonies. This results in colonies becoming effectively borderless, expanding as a single, massive colony across large geographic distance. These ants are known to be unicolonial in some parts of their range, but no studies to date have assessed unicoloniality in Florida populations. To determine whether LFA populations across Florida were members of a unicolonial lineage, we carried out integration trials using 27 colonies from 6 sites in 3 Florida counties. Approximately 20 workers from different colonies were placed together in an arena; after 24 hours they were evaluated to determine whether or not they integrated. Out of a total of 42 trials, 17 (40%) resulted in full integration and 25 (60%) did not. Colonies that were collected within 9 km of each other integrated, and ants from colonies beyond that distance did not integrate. These results suggest that the little fire is not unicolonial in Florida on a large scale, but perhaps on a smaller scale. Future studies should attempt to use colonies from more counties and incorporate genetic data to determine relatedness among these ants.