Influence of lethal and sublethal exposure to clothianidin on the seven-spotted lady beetle, Coccinella septempunctata L. (Coleoptera: Coccinellidae)

The seven-spotted ladybird beetle, Coccinella septempunctata L., as a dominant predator of aphids, has played a crucial role in integrated pest management (IPM) strategies in agricultural ecosystems. To study the risk of insecticides to C. septempunctata, the neonicotinoid clothianidin was selected for evaluation of its influence on C. septempunctata at lethal and sublethal doses. The LR₅₀ (application rate causing 50% mortality) in the exposed larvae decreased from 19.94 to 5.91 g a.i. ha^-1, and the daily HQ (hazard quotient) values increased from 3.00 to 10.15, indicating potential intoxication risks. We also determined NOERs (No Observed Effect application Rates) of clothianidin on the total developmental time (10 g a.i. ha^-1), survival (2.5 g a.i. ha^-1) and pupation (5 g a.i. ha^-1). Moreover, clothianidin at a NOER of 2.5 g a.i. ha^-1 did not profoundly affect adult emergence, fecundity or egg hatchability. The total effect (E) assessment also showed that clothianidin at 2.5 g a.i. ha^-1 was slightly harmful to C. septempunctata. These results suggested that clothianidin would impair C. septempunctata when applied at over 2.5 g a.i. ha^-1 in the field. Conservation of this biological control agent in agricultural ecosystems thus requires further measures to decrease the applied dosages of clothianidin.