Ecological impacts on native ant and ground-dwelling animal communities through Argentine ant (Linepithema humile) (Hymenoptera: Formicidae) management in Japan

In the last 30 years some limited successes in alien ant control have been documented globally, and control programs remain challenging. Moreover, the potential non-target impacts of toxicants have not been well studied. We assessed the efficacy and non-target effects of multiple products containing the active compound fipronil in the attempted control of two populations of the invasive Argentine ant Linepithema humile (Mayr) in Tokyo, Japan. Three treatments were conducted: control, low-dose treatment (0.1 g/ha per treatment), and high-dose treatment (0.2 g/ha). Treatments were applied once per month for 11 months. The abundance of L. humile declined rapidly by up to 99.8 % in treated areas, but remained at extremely high densities in the control area. The treatments had few negative non-target effects, with the abundances of native ant species and other ground-dwelling invertebrates except for cockroaches being greater in the treated areas after L. humile suppression. Thus, fipronil is an effective compound for controlling L. humile and can be used with minimal toxic effects on non-target organisms. The treatments cost approximately US$ 575/ha for the low-dose treatment and US$ 1250/ha for the high-dose treatment. Our research supports the creation of more ambitious invasive ant management projects.