Eradicating Wasmannia auropunctata (Hymenoptera: Formicidae) from Maui, Hawaii: The Use of Combination Treatments to Control an Arboreal Invasive Ant

Abstract

A small infestation of Wasmannia auropunctata (little fire ant) was discov- ered on the island of Maui, Hawaii in September 2009. After delimiting the infestation, we treated it on twelve occasions over the course of a year using two types of granular baits for the ground layer and a paste bait containing indoxacarb (0.18% a.i.) on the vegetation. These treatments rapidly reduced the W. auropunctata population with only a single ant recorded after five months treatment and none thereafter. To date, one year after initiation of treatments, no further positive detections have been observed and we tentatively report the eradication of this species from Maui. The key components of the treatment program contributing to its success to date have been the baiting of arboreal nests with a formulation designed for use on vegetation and the strategy of baiting repeatedly even after no ants could be detected with conventional survey methods. The response to the detection of this invasive species on Maui is a successful example of multi-agency collaboration and cooperation necessary for invasive species management. We recommend that future eradication and control attempts for this species include treatment of the arboreal components of infested habitats.