Assessment of acute and chronic toxicity of cyantraniliprole and sulfoxaflor on honey bee (Apis mellifera) larvae

BACKGROUND Recently, cyantraniliprole (CYA) and sulfoxaflor (SUL) have been considered as alternatives to neonicotinoid insecticides. In this study, we evaluated the acute and chronic toxicities of CYA and SUL on honey bee (Apis mellifera L.) larvae reared in vitro. RESULTS In the acute toxicity test, the following test doses were used to determine the median lethal dose (LD50): CYA 0.007, 0.014, 0.028, 0.056 and 0.112 mu g larva(-1); SUL 2.5, 5, 10, 20 and 40 mu g larva(-1). In the chronic toxicity test, the following test doses were used to determine the LD50: CYA 0.00512, 0.0128, 0.032, 0.08 and 0.2 mu g larva(-1); SUL 0.0625, 0.125, 0.25, 0.5 and 1.0 mu g larva(-1). The acute LD50 values of CYA and SUL were 0.047 and 11.404 mu g larva(-1), respectively. Larvae acutely exposed to SUL had significantly lower body weight than controls, but those exposed to CYA showed no difference. The no observed adverse effect level (NOAEL) and LD50 values of the chronic toxicity tests for each insecticide were 0.00512 and 0.064 mu g larva(-1) for CYA, and 0.0625 mu g larva(-1) and 0.212 mu g larva(-1) for SUL, respectively. Larvae chronically exposed to SUL emerged as bees with deformed wings, reaching adult deformation rates of over 50%; however, CYA had no effect on adult deformation. CONCLUSION Exposure to CYA increased larval mortality but did not cause any adult deformation, whereas SUL exposure increased pupal mortality and caused wing deformation in newly emerged bees. Our study may be useful for the assessment of pesticide toxicity by providing valuable findings on the effects of these insecticides on honey bee larvae. (c) 2022 Society of Chemical Industry.