吡虫啉和噻虫嗪对苜蓿盲蝽的防治效果及其在苜蓿中的残留

为了评价新烟碱类杀虫剂吡虫啉和噻虫嗪对苜蓿盲蝽的防治效果及安全性，采用田间喷雾法测定了20%吡虫啉可溶液剂(SL)和30%噻虫嗪悬浮剂(SC)对苜蓿盲蝽的防治效果，使用超高效液相色谱-串联质谱法(UPLC-MS/MS)测定了施药1、2、3次后(间隔7 d),药剂在苜蓿中的残留情况。结果表明，当吡虫啉和噻虫嗪在施药剂量分别为25.02 g/hm²和18.00 g/hm²时，药后3～7 d对苜蓿盲蝽的防治效果分别为80.01%～82.01%和77.54%～83.29%。吡虫啉和噻虫嗪连续施药3次后，在苜蓿中的最终残留量分别为1.90 mg/kg和0.08 mg/kg,吡虫啉已超过我国食品安全国家标准GB 2763-2021规定的果蔬中的最大残留限量(0.5 mg/kg)。因此建议每茬苜蓿生长期，可选用吡虫啉和噻虫嗪防治苜蓿盲蝽，吡虫啉和噻虫嗪喷施次数分别不宜超过2次和3次。

Control effects of imidacloprid and thiamethoxam on Adelphocoris lineolatus and their residues in alfalfa

In order to evaluate the control effect and safety of neonicotinoid insecticides imidacloprid and thiamethoxam, the control efficacies of imidacloprid 20% SL and thiamethoxam 30% SC on Adelphocoris lineolatus were measured by spray method. After spraying once, twice and three times at seven days intervals, the final residues of imidacloprid and thiamethoxam in alfalfa were determined by liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). Three to seven days after application, the efficacy of imidacloprid and thiamethoxam against A. lineolatus at application dosage of 25.02 g/hm2 and 18.00 g/hm2 were 80.01%-82.01% and 77.54%-83.29%, respectively. The final residues of imidacloprid and thiamethoxam in alfalfa were 1.90 mg/kg and 0.08 mg/kg, respectively, after three successive applications. The content of imidacloprid has exceeded the maximum residue limit (0.5 mg/kg) of fruits and vegetables in national food safety standard GB 2763-2021. Therefore, it is suggested that imidacloprid and thiamethoxam can be used to control mirid bugs, and their spraying times should not exceed two and three times, respectively, in each alfalfa growth period.