Behavioral Response of Little Fire Ant, Wasmannia auropunctata (Hymenoptera: Formicidae), to Trail Chemicals Laid on Epiphytic Moss

Abstract

The little fire ant (LFA), Wasmannia auropunctata (Hymenoptera: Formicidae), is native to the neotropics, but has become one of the world’s most widespread and destructive invasive ants. In Hawaii, LFA was first discovered in 1999 on the Big Island and since then has rapidly spread to neighboring islands, causing ecological and economic damage. LFA can develop fully functional nests on the ground and arboreally, and their foraging and retrieval of food resources is facilitated by a well-developed recruitment system. LFA were found to form recruitment trails on epiphytic moss growing on macadamia nut trees. As a first step to identify LFA recruitment pheromone components, we tested the LFA worker trail-following response to naturally marked epiphytic moss trails. Significantly more LFA workers placed on a natural trail followed the trail and made 90° turns to continue following the trail compared to when they were placed on a fake trail that had no trail marking substance(s). In laboratory choice assays using hexane extracts of moss with and without LFA trail, LFA workers preferred to follow a trail drawn with a hexane extract of moss that had a recruitment trail over a trail drawn with a hexane extract of moss only. Our results confirm that LFA workers readily follow a trail marking substance(s) laid down on epiphytic moss.