9种杀虫剂对中华大刀螂幼虫的毒性

Toxicity of Nine Kinds of Insecticides to Paratenodera sinensis Saussure Larva

螳螂是田间控制害虫种群增加的重要捕食性天敌之一。以中华大刀螂3龄幼虫(Paratenodera sinensis Saussure)为受试生物,利用9种常用杀虫剂配制成不同浓度梯度的药剂,通过喷雾法直接暴露,分别测定了LC50和死亡率来评价不同杀虫剂对中华大刀螂毒性和危害程度的影响。结果显示,9种杀虫剂对中华大刀螂幼虫的毒性(LC50值)差异很大,用药后24h的LC50在0.7182～347.7962mg·L-1之间,LC95在8.8057～1734.5650mg·L-1之间;用药后48h的LC50在0.3564～193.6887mg·L-1之间,LC95在3.8958～1548.3258mg·L-1之间;用药后72h的LC50在0.2232～115.3391mg·L-1之间,LC95在1.7730～530.6462mg·L-1之间。不同杀虫剂对中华大刀螂幼虫的毒性差异最高达到543.46倍。毒性大小依次为,高效氯氟氰菊酯﹥啶虫脒﹥联苯菊酯﹥毒死蜱﹥噻虫嗪﹥茚虫威﹥吡虫啉﹥阿维菌素﹥苏云金杆菌原粉(Bt)。根据田间推荐浓度处理的死亡率判断,毒死蜱、联苯菊酯、啶虫脒、高效氯氟氰菊酯为有害水平,Bt为中度有害水平,吡虫啉、茚虫威、噻虫嗪为微害水平,阿维菌素接近无害水平。根据LC50与田间推荐浓度的比值判断,阿维菌素、吡虫啉对螳螂种群数量不会产生太大影响;Bt、茚虫威和噻虫嗪对螳螂种群数量会产生一定危害;而毒死蜱、啶虫脒、联苯菊酯和高效氯氟氰菊酯将严重影响螳螂种群数量的稳定性。在24～72h范围内,不同杀虫剂LC50和LC95随施药时间的延长而降低,说明暴露时间越长毒性越大,危害程度也越大。建议在中华大刀螂生活范围内减少高效氯氟氰菊酯、联苯菊酯、啶虫脒和毒死蜱的施用,推荐杀虫剂田间使用量时,除考虑对防治对象的防效,还应考虑对天敌种群的危害,提高药剂使用安全性,保护天敌种群的稳定性。

Mantis is one of the important predators in fields to control pest populations. In this study, the 3 - instar mantis （Paratenodera sinensis Saussure） was exposed to different concentrations of nine kinds of commonly used insecticides. LC50 and mortality were measured to evaluate the toxicity of various insecticides to mantis. The results showed that there was significant difference in toxicity （LC50） to mantis between these insecticides. After mantis exposed to the insecticides for 24 h, the range of LC50 values was in 0.7182 - 347.7962 mg·L-1, and that of LC95 values was in 8.8057 - 1 734.5650 mg. L- 1 . After mantis 48 h exposure to the insecticides, LC50 and LC95values were in the range of 0.3564 -193.6887 mg·L-1 and 3.8958 -1 548.3258 mg·L-1, respectively. LC50 values were 0.2232 - 115.3391 mg ·L-1, and the LC95 values were 1.7730 ~ 530.6462 mg·L-1 after a 72 h exposure to the insecticides. The most significant difference among the toxicity of the insecticides to mantis was up to 543.46 times. The order of toxicity to mantis was lambda - cyhalothfin 〉 acetarniprid 〉 bifenthrin 〉 chlorpyrifos 〉 thiamethoxam 〉 indoxacarb 〉 irnidacloprid 〉 abamectin 〉 Bacillus thuringiensis （Bt）. According to the mortality of mantis tested in recommended in field doses of insecticides, to mantis, chlorpyrifos, bifenthrin, acetamiprid and lambda - cyhalothrin were toxic, Bt was in a moderate level. Imidacloprid, in- doxacarb and thiamethoxam were in very low toxicity, and abamectin was nearly harmless. According to the ra- tio of LCs0 to field recommended concentration, the use of abamectin and imidacloprid did not affect the mantis population. While Bt, indoxacarb and thiamethoxam could influence mantis population, and chlorpyrifos, acetamiprid, bifenthrin and lambda-cyhalothrin seriously affected the stability of the population. In the exposure time range of 24 to 72 h, LCs0 and LC95 of pesticides decreased with increase of exposure time, indicating that toxic effect of pesticides was proportional to exposure time. Therefore, lambda - cyhalothrin, bifenthrin, acetamiprid and chlorpyrifos were suggested to reduce the application to mantis＇s living areas. To the recommended field usage, not only the effects of pest control but also the hazards to natural enemies should be considered to increase the use safety of pesticide and protect the stability of natural enemy population.