Effects of contaminants on bait acceptance by Solenopsis invicta (Hymenoptera: Formicidae)

Three commonly used fire ant baits, Amdro (0.73% hydramethylnon [AI]), Ascend (0.011% abamectins [AI]), and Maxforce (1.0% hydramethylnon [AI]), were exposed to potential, volatile contaminants. The contaminants included the insecticides Orthene Fire Ant Killer (75.0% acephate [AI] ), Cyren (44.6% chlorpyrifos [AI]), and Tempo 2 (24.3% cyfluthrin [AI]); cigarette smoke; gasoline (unleaded, 89 octane); and fertilizer (10-10-10). Fire ant baits previously exposed for 48 h to these contaminants were analyzed using gas chromatography analysis. Orthene Fire Ant Killer, Cyren, Tempo 2, cigarette smoke, and gasoline had volatile components transferred to the baits. Baits exposed to these products were used in a field evaluation of bait acceptance by Solenopisis invicta Buren, the red imported fire ant. Uncontaminated Amdro was significantly preferred by S. invicta over Amdro contaminated by smoke, Cyren, Tempo 2, and gasoline. Uncontaminated Maxforce was significantly preferred over Maxforce contaminated by Tempo 2, Cyren, and gasoline, and uncontaminated Ascend was preferred over Tempo 2- and Cyren-contaminated Ascend. Orthene-exposed Amdro, Maxforce, and Ascend baits, and smoke-exposed Maxforce and Ascend baits were not significantly different from the control. These results indicate that volatile insecticides and products can contaminate fire ant baits. Some insecticides and products, such as gasoline, can significantly affect bait palatability and may adversely impact control.