Effect of chlorfenapyr exposure on Solenopsis invicta Buren (Hymenoptera: Formicidae)

Red imported fire ant (RIFA), Solenopsis invicta Buren, pose a serious risk to the agriculture, 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 a novel and cost-effective compound for controlling fire ants, we examined the toxic effect of chlorfenapyr on fire ants. Results had showed that while chlorfenapyr exhibited an insufficient horizontal toxicity transfer and knockdown effect to fire ants, feeding with chlorfenapyr solution increased fire ant workers' gathering abilities while decreasing their walking, climbing, and adhesion ability. Additionally, females and males exhibited more higher tolerance than workers to chlorfenapyr; meanwhile, females showed a 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. Additionally, the chlorfenapyr bait exhibited significant toxicity on fire ants. It was impressive that 0.01% chlorfenapyr bait showed a better toxic effect than 0.025% during the period of 2 d-7 d. However, the weight of ant corpses was 1.32 and 1.23 g at 12 d of treatment with 0.025% and 0.01% chlorfenapyr bait, respectively. The present research showed that chlorfenapyr appeared to be a potential toxic compound for bait to manage S. invicta.Red imported fire ant (RIFA), Solenopsis invicta Buren, pose a serious risk to the agriculture, 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 a novel and cost-effective compound for controlling fire ants, we examined the toxic effect of chlorfenapyr on fire ants. Results had showed that while chlorfenapyr exhibited an insufficient horizontal toxicity transfer and knockdown effect to fire ants, feeding with chlorfenapyr solution increased fire ant workers' gathering abilities while decreasing their walking, climbing, and adhesion ability. Additionally, females and males exhibited more higher tolerance than workers to chlorfenapyr; meanwhile, females showed a 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. Additionally, the chlorfenapyr bait exhibited significant toxicity on fire ants. It was impressive that 0.01% chlorfenapyr bait showed a better toxic effect than 0.025% during the period of 2 d-7 d. However, the weight of ant corpses was 1.32 and 1.23 g at 12 d of treatment with 0.025% and 0.01% chlorfenapyr bait, respectively. The present research showed that chlorfenapyr appeared to be a potential toxic compound for bait to manage S. invicta