Testing the Attractiveness and Efficacy of Baits for the Monitoring and Control of the Thief Ant, Solenopsis papuana

Abstract

Solenopsis papuana is one of the few introduced ant species that have widely infiltrated undisturbed mesic and wet forests in Hawaii. This may be problematic since many endemic Hawaiian insects are limited to mountain forests, and methods for monitoring and controlling S. papuana would be useful. Four non-toxic monitoring baits (corn syrup, SPAM®, peanut butter, and tuna/ corn syrup blend) and five ant pesticide baits (Advion® Fire Ant BaitTM, Amdro® Ant Block®, ExtinguishTM Plus, MaxForce® Complete Brand Granular Insect Bait, and SiestaTM) were tested for attractiveness to S. papuana in choice tests at Lyon Arboretum and Pahole Natural Area Reserve (NAR) on the island of Oahu. Amdro® Ant Block® and SiestaTM were also tested for efficacy against S. papuana in field plots at Pahole NAR. SPAM® and peanut butter were the most attractive monitoring baits at both locations. There were few significant differences in at- tractiveness among the five ant pesticides, but Amdro® Ant Block® attracted the highest or second highest number of ants at both sites, while rankings among the other baits were inconsistent. Amdro® Ant Block® presented in bait stations 2.5 m apart greatly reduced the number of ants at monitoring cards in field plots, by an average of 96% from pre-treatment levels over the course of the 246-day trial. Ant numbers also declined in the SiestaTM plots (by 77%), but more closely mir- rored fluctuations in the untreated control plots. These methods were effective for monitoring and suppressing S. papuana populations in localized natural areas in the Waianae Mountain Range.