Insecticidal effect of chlorantraniliprole against major stored-product insect pests in different grain commodities...

Chlorantraniliprole belongs to the chemical group of anthranilic diamides. It has selectivity to beneficial arthropods and low mammalian toxicity. Laboratory bioassays were conducted to assess chlorantraniliprole as a potential grain protectant against Ephestia kuehniella Zeller larvae, Liposcelis bostrychophila Badonnel adults, Rhyzopertha dominica (F.) adults, Sitophilus oryzae (L.) adults and Tribolium confusum Jacquelin du Val adults and larvae. Factors such as dose (0.01, 0.1, 1 and 10 mg chlorantraniliprole kg(-1) grain), exposure interval (7 and 14 days), formulation (chlorantraniliprole WG and chlorantraniliprole SC) and commodity (barley, maize, oats, peeled rice, whole rice and wheat) were evaluated for their impact on the insecticidal activity of chlorantraniliprole. Progeny production was assessed after 45 days of exposure in the case of L. bostrychophila adults and after 60 days of exposure in the case of R. dominica, S. oryzae and T. confusum adults.

For L. bostrychophila adults, after 7 days of exposure, mortality was lower in maize and whole rice in comparison with the other commodities. Increase in dose generally increased mortality. Similar trends were also noted after 14 days of exposure. Offspring emergence was higher in maize and whole rice in comparison with the other commodities. For E. kuehniella larvae, after 7 days of exposure, significant differences were noted among the tested commodities. Increase in dose only slightly increased mortality in all commodities. After 14 days of exposure, mortality was further increased, but did not reach 100%. For R. dominica adults, after 7 days of exposure, increase in dose increased mortality significantly. After 14 days of exposure, mortality in barley, maize, whole rice and wheat exceeded 92% at 10 mg chlorantraniliprole kg(-1) grain. Offspring emergence was reduced, but 100% progeny suppression was not achieved. For S. oryzae adults, after 7 days of exposure, mortality was generally low at dose rates of ≤1 mg chlorantraniliprole kg(-1) grain. After 14 days of exposure, 100% mortality was noted in whole rice. For T. confusum adults, after 7 days of exposure, mortality was low. After 14 days of exposure, mortality increased proportionately for all commodities. Most progeny production was noted in oats. For T. confusum larvae, after 7 days of exposure, mortality was generally higher in comparison with adults. After 14 days of exposure, mortality in maize was high. Generally, the two formulations performed alike for all the insects tested.

Based on the results of the present work, chlorantraniliprole is effective against major stored-product insect species. However, efficacy depends upon the type of commodity, the dose rate and the exposure interval.