We have developed techniques for measuring insecticide runoff from single houses after treatments for ant infestations. Until now most research on insecticide runoff has sampled water from urban storm drains or creeks to look for insecticides. Those methods reflect runoff from whole communities and cannot be assigned to any specific persons or techniques that were used. Our ability to measure runoff from single homes now allows us to compare specific application techniques by the homeowner or pest management professionals (PMP) both for their efficacy against the ants and for the amount of the runoff produced. Ant efficacy is measured by the amount of sugar water consumed by ants at bait stations. To measure insecticide runoff we collect a 1 L sample from the irrigation runoff and analyze it by gas chromatography to determine the concentration of the insecticide. Using these techniques we compared several application techniques both for efficacy against ants and insecticide runoff. In this study we compared a standard 1-gal application of fipronil around a house foundation using a fan spray 1 ft up and1 ft out with a similar application of fipronil as a wet foam. A third treatment was identical to the first but with no treatments done on the driveway and garage door. With respect to insecticide runoff, the foam application had slightly less runoff than the standard treatment for every time period. At 8 weeks a driveway flush showed significantly less runoff when the driveway was not treated. In terms of efficacy, the 3 treatments were similar in outcome, with reductions in ant numbers at 60-80%.

Les Greenberg. Department of Entomology University of California Riverside, CA

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