Abstract: 【Aim】 This study aims to assess the selective toxicity of six neonicotinoid insecticides and one novel insecticide triflumezopyrim to Thrips hawaiiensis and its natural enemy Orius strigicollis so as to provide a basis for the combined control of T. hawaiiensis using O. strigicollis and insecticides. 【Methods】 The acute toxicity of six neonicotinoid insecticides including imidacloprid, dinotefuran, flupyradifurone, imidaclothiz, nitenpyram and thiamethoxam, and triflumezopyrim to T. hawaiiensis adults and the 5th instar nymphs of O. strigicollis was determined using the residual film method, and their exposure risks to the 5th instar nymphs of O. strigicollis were assessed. 【Results】 The median lethal rates (LR₅₀ values) of these seven insecticides to T. hawaiiensis adults were lower than their maximum recommended field application rates. The LR₅₀ value of imidaclothiz to T. hawaiiensis adults was the lowest (0.183 g a.i/hm²), significantly lower than those of the other insecticides, whereas those of flupyradifurone and triflumezopyrim were 3.066 and 3.949 g a.i/hm², significantly higher than those of other insecticides. The LR₅₀ values of the two nitenpyram formulations 20% nitenpyram SL and 10% nitenpyram AS to T. hawaiiensis adults were 0.327 and 0.201 g a.i/hm², and those of the two thiamethoxam formulations 70% thiamethoxam WG and 25% thiamethoxam WG were 0.970 and 0.685 g a.i/hm², respectively. The toxicity of nitenpyram and thiamethoxam in different formulations and with different contents to T. hawaiiensis adults was significantly different. The LR₅₀ values of the tested six neonicotinoid insecticides to the 5th instar nymphs of O. strigicollis were lower than their maximum recommended field application rates, while that of triflumezopyrim to the 5th instar nymphs of O. strigicollis was higher than its maximum recommended field application rate. The toxicity of triflumezopyrim to the 5th instar nymphs of O. strigicollis was the lowest, with the LR₅₀ value of over 65.736 g a.i/hm², and that of imidacloprid and dinotefuran followed, with the LR₅₀ values of 21.317 and 24.486 g a.i/hm², respectively. Imidacloprid, dinotefuran, and triflumezopyrim showed high selective toxicity to T. hawaiiensis adults and the 5th instar nymphs of O. strigicollis. The risks of imidacloprid and triflumezopyrim to O. strigicollis adults were acceptable in two exposure scenarios in- and off-field. However, the risks associated with imidaclothiz and thiamethoxam to the 5th instar nymphs of O. strigicollis were unacceptable. 【Conclusion】 T. hawaiiensis adults have extremely high sensitivity to six neonicotinoid insecticides and triflumezopyrim. Imidacloprid and triflumezopyrim exhibit low risks to the 5th instar nymphs of O. strigicollis, and triflumezopyrim has high compatibility with O. strigicollis. The combination of triflumezopyrim with O. strigicollis shows a promising potential for the management of T. hawaiiensis.

Key words: Thrips hawaiiensis; Orius strigicollis, neonicotinoid insecticides, triflumezopyrim, acute toxicity, risk assessment