Behavioral response of little fire ant, Wasmannia auropunctata (Hymenoptera: Formicidae), to trail chemicals laid on epiphytic moss

Authors: Cha, Dong; Skabeikis, Dominick; COLLIGNON, MAX - Eastern Mennonite University; SIDERHURST, MATTHEW - Eastern Mennonite University; Choi, Man-Yeon; Vander Meer, Robert - Bob

Submitted to: Journal of Insect Behavior
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/27/2019
Publication Date: 7/6/2019
Citation: Cha, D.H., Skabeikis, D.D., Collignon, M.R., Siderhurst, M.S., Choi, M.Y., Vander Meer, R.K. 2019. Behavioral response of little fire ant, Wasmannia auropunctata (Hymenoptera: Formicidae), to trail chemicals laid on epiphytic moss. Journal of Insect Behavior. 32:145-152. https://doi.org/10.1007/s10905-019-09721-0.
DOI: https://doi.org/10.1007/s10905-019-09721-0

Interpretive Summary: After the initial detection in 1999, the little fire ant (LFA) has become a serious economic and environmental pests in Hawaii. Baits are considered the most viable and environmental friendly control option. In particular, it is the most effective method to kill the 90% of ants that generally hide in their nest, as foraging workers deliver toxic baits to other members in the nest, including reproducing queens. However, current ant baits are not developed to target LFA and not particularly attractive to workers of LFA, which reduces the efficacy of the baits. Therefore, researchers at the USDA-ARS laboratories in HI, OR, and FL and at Eastern Mennonite University in VA are identifying recruitment trail pheromone component(s) of LFA, which can be used to enhance the attractiveness and thus the efficacy of the bait. The first essential step for the identification of trail pheromone is to locate the source of the pheromone. By using carefully designed behavioral tests in the laboratory and field, the authors identified a convenient source of trail pheromone—the chemicals deposited by LFA workers on LFA trails formed on epiphytic moss. Future research will be focused on identifying LFA recruitment trail pheromone component(s) and exploring their use for improved LFA management.

Technical Abstract: The little fire ant (LFA), Wasmannia auropunctata Roger (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.