广东草地贪夜蛾对2种常用农药的抗药性及助剂和增效剂对农药毒力的影响

Resistance of Spodoptera frugiperda in Guangdong against two commonly used pesticides and the effects of auxiliaries and synergist on toxicity to pesticides

【目的】明确广东地区草地贪夜蛾(Spodoptera frugiperda)低龄幼虫对2种常用农药[甲氨基阿维菌素苯甲酸盐(甲维盐)和氯虫苯甲酰胺]的抗药性,并探索添加农药助剂和有机硅对草地贪夜蛾高龄幼虫毒力效果的影响,为广东省草地贪夜蛾的抗药性监测、合理化学防治、农药减量增效应用和抗性治理提供科学依据。【方法】采用浸叶法测定甲维盐和氯虫苯甲酰胺对广东省佛山、茂名和韶关市草地贪夜蛾田间种群2龄幼虫的毒力,将不同地理种群的半致死浓度(LC50)与相对敏感种群(SS)进行比较,计算抗性倍数;测定甲维盐、甲维盐乳油、甲维盐乳油+有机硅及氯虫苯甲酰胺、氯虫苯甲酰胺悬浮剂、氯虫苯甲酰胺悬浮剂+有机硅对草地贪夜蛾4龄幼虫的室内毒力,比较不同制剂对草地贪夜蛾的校正死亡率。【结果】抗药性试验结果表明,茂名种群对甲维盐和氯虫苯甲酰胺的抗性倍数分别为14.3702和23.1757,处于中等水平抗性,其余地区种群对这2种药剂均处于低水平抗性。室内毒力测定结果表明,农药按剂型要求制成制剂以及添加有机硅增效剂对甲维盐和氯虫苯甲酰胺均表现增效作用,甲维盐乳油和甲维盐乳油+有机硅在24 h时的LC50分别为1.4935和1.1872 mg/L,对4龄幼虫48 h的校正死亡率均在90.00%以上;氯虫苯甲酰胺悬浮剂和氯虫苯甲酰胺悬浮剂+有机硅在24 h时的LC50分别为2.1789和1.7518 mg/L,对4龄幼虫48 h的校正死亡率均在85.00%以上。【结论】2019年监测地区的草地贪夜蛾田间种群对甲维盐和氯虫苯甲酰胺均已产生不同程度的抗药性;助剂和有机硅均可不同程度提高甲维盐和氯虫苯甲酰胺对草地贪夜蛾的防治效果。

【Objective】Resistance of young larvae of Spodoptera frugiperda against two commonly used pesticides(emamectin benzoate and chlorantraniliprole)in Guangdong and the effects of adding pesticides auxiliaries and organosilicon toxicity to older larvae of S.frugiperda were researched.To provide a scientific basis for pesticides resistance monitoring,rational chemical control,pesticide dosage reduction and synergistic application and resistance management of S.frugiperda in Guangdong.【Method】The toxicities of emamectin benzoate and chlorantraniliprole on 2nd instar larvae S.frugiperda were tested with leaf immersion method in Foshan,Maoming and Shaoguan in Guangdong.The lethal concentrations(LC50)in different geographical populations were compared with that in relatively sensitive populations(SS)and re sistance times was calculated.The indoor toxicities of the emamectin benzoate,emamectin benzoate EC,emamectin benzoate EC+organosilicon,chlorantraniliprole,chlorantraniliprole SC and chlorantraniliprole SC+organosilicon to 4th instar larvae of S.frugiperda were determined with leaf immersion method in laboratory.Corrected mortality rates of different pesticides formulation against S.frugiperda were compared.【Result】The results of pesticides resistance tests showed that the pesticides resistance rates of S.frugiperda population from Maoming to emamectin benzoate and chlorantraniliprole were 14.3702 and 23.1757 respectively,which showed intermediate level resistance.The populations collected from other areas showed lowlevel resistance to the two insecticides.The results also showed that pesticide dosage forming into agents according to the requirement and additive of organosilicon synergistic agent on emamectin benzoate and chlorantraniliprole presented synergistic effects.At 24 h,LC50 of emamectin benzoate EC and emamectin benzoate EC+organosilicon were 1.4935 and 1.1872 mg/L respectively.The corrected mortalities of pesticides against 4th instar larvae S.frugiperda were over 90.00%after 48 h.At 24 h,LC50 of chlorantraniliprole SC and chlorantraniliprole SC+organosilicon were 2.1789 and 1.7518 mg/L,respectively.The corrected mortality of pesticides against 4th instar larvae S.frugiperda was over 85.00%after 48 h.【Conclusion】The varying degrees insecticide resistances of S.frugiperda to emamectin benzoate and chlorantraniliprole in monitoring areas in 2019 has been generated.Auxiliaries and organosiliconcan improve the control effect of emamectin benzoate and chlorantraniliprole against S.frugiperda to different levels.