Toxicity of Chlorfenapyr and Its Impact on Behavior of Solenopsis invicta Buren

Red imported fire ants, Solenopsis invicta Buren, pose a serious risk to agriculture, the environment, and public health in areas invaded by this species. Chemical insecticides have been widely used to prevent and control this plaguing pest. To discover novel and cost-effective material for controlling fire ants, we examined the contact and oral toxicity of chlorfenapyr as well as its effect on fire ants’ behavior. Results had showed that feeding with chlorfenapyr solution increased fire ant workers' gathering abilities while decreasing their walking, climbing, and adhesion ability. Females and males exhibited more higher tolerance than workers to chlorfenapyr; meanwhile, females showed more higher resistance than males. That is, the mortalities of the small, medium, and large-size workers were 84.17%, 98.75%, and 82.08%, respectively, after 72 h of treatment with 25, 50, and 200 μg/mL chlorfenapyr. The mortality of males was 100% after 120 h of treatment with 6.25 μg/mL chlorfenapyr. In contrast, the mortality of females was 79.05% after 144 h of treatment with 100 μg/mL chlorfenapyr. In the present research, chlorfenapyr appears to be a potential toxic compound in the S. invicta baits.