六种新烟碱类杀虫剂和三氟苯嘧啶对黄胸蓟马及南方小花蝽的选择毒性

【目的】评估6种新烟碱类杀虫剂和1种新型杀虫剂三氟苯嘧啶对黄胸蓟马Thrips hawaiiensis及其天敌南方小花蝽Orius strigicollis的选择毒性，为杀虫剂与南方小花蝽联合防控黄胸蓟马提供依据。【方法】采用药膜法测定吡虫啉、呋虫胺、氟吡呋喃酮、氯噻啉、烯啶虫胺和噻虫嗪6种新烟碱类杀虫剂及三氟苯嘧啶对黄胸蓟马成虫的毒力及对南方小花蝽5龄若虫的急性毒性，并评估其对南方小花蝽5龄若虫的暴露风险。【结果】供试的7种杀虫剂对黄胸蓟马成虫的半致死用量(median lethal rate, LR₅₀)均低于田间最大推荐用量。氯噻啉对黄胸蓟马成虫的LR₅₀值最低(0.183 g a.i/hm²)，显著低于其他杀虫剂；氟吡呋喃酮和三氟苯嘧啶对黄胸蓟马成虫的LR₅₀值分别为3.066和3.949 g a.i/hm²，显著高于其他杀虫剂；两种烯啶虫胺制剂(20%烯啶虫胺可溶液剂和10%烯啶虫胺水剂)对黄胸蓟马成虫的LR₅₀分别为0.327和0.201 g a.i/hm²；两种噻虫嗪制剂(70%噻虫嗪水分散粒剂和25%噻虫嗪水分散粒剂)对黄胸蓟马成虫的LR₅₀值分别为0.970和0.685 g a.i/hm²；不同剂型和含量的烯啶虫胺和噻虫嗪对黄胸蓟马成虫的毒力差异显著。测试的6种新烟碱类杀虫剂对南方小花蝽5龄若虫的LR₅₀值均低于田间最大推荐用量，而三氟苯嘧啶对南方小花蝽5龄若虫的LR₅₀值高于田间最大推荐用量。三氟苯嘧啶对南方小花蝽5龄若虫的毒性最低(LR₅₀>65.736 g a.i/hm²)，吡虫啉和呋虫胺次之(LR₅₀值分别为21.317和24.486 g a.i/hm²)。吡虫啉、呋虫胺、三氟苯嘧啶对黄胸蓟马成虫和南方小花蝽5龄若虫具有较高的选择毒性。三氟苯嘧啶和吡虫啉对农田内、农田外南方小花蝽的风险均可接受，氯噻啉和噻虫嗪均不可接受。【结论】黄胸蓟马成虫对6种新烟碱类杀虫剂和三氟苯嘧啶均具极高的敏感性，其中以吡虫啉和三氟苯嘧啶对南方小花蝽5龄若虫的风险较低；三氟苯嘧啶与南方小花蝽兼容性较高，二者在黄胸蓟马的联合防控中具备良好的潜力。

Selective toxicity of six neonicotinoid insecticides and triflumezopyrim toThrips hawaiiensis(Thysanoptera: Thripidae) and Orius strigicollis (Heteroptera: Anthocoridae)

【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.