Chlorantraniliprole as seed treatments against the black cutworm Agrotis ipsilon (Lepidoptera: Noctuidae) via residues in cotton ecosystem and the exposure risks to honeybees as measured in pollen

The black cutworm Agrotis ipsilon (Hufnagel) (Lepidoptera: Noctuidae) can damage the cotton seedlings and induce destructive yield loss. Seed coating with systemic insecticides is a cost-effective alternative to control A. ipsilon during the early stage of cotton, but the control efficacy and exposure risk to honeybees remain unclear. This study evaluated the control effects of the anthranilic diamide insecticide chlorantraniliprole on A. ipsilon in cotton crops and the corresponding exposure risks to honeybees. Field studies revealed the control efficacy of chlorantraniliprole at 2 or 4 g/kg seed was greater than 75%, which was comparable to its spray control during the seedling development stage. A residual toxicity trial revealed that chlorantraniliprole treatment had a dose-response control effect on A. ipsilon during the 19 days after sowing. The residue levels of chlorantraniliprole in the stem bases and soil were found consistent with the residual toxicity against A. ipsilon. In the cotton flowering period, the highest detection frequency and residue of chlorantraniliprole were found in pollen from the plots treated with 4 g/kg seed. By using 2 independent risk assessment approaches, the exposure risk of chlorantraniliprole seed treatments were evaluated to be acceptable to honeybees. Overall, chlorantraniliprole coated with 2 g/kg seed was an effective alternative for controlling A. ipsilon at the cotton seedling stages.