药剂对小菜蛾抗性及敏感品系乙酰胆碱酯酶抑制作用比较

采用浸叶法测定了云南通海、元谋和澜沧的小菜蛾plutella xylostella田间种群对常用杀虫剂的抗药性。结果表明,云南上述地区小菜蛾田间种群对各类杀虫剂均产生了不同程度的抗性。对有机磷类药剂的抗药性为1.74~31.1倍;对菊酯类药剂的抗药性为7.41~764倍;对阿维菌素类药剂则产生了 5.60~4.06×104倍的抗性。通过离体和活体试验测定了药剂对小菜蛾头部乙酰胆碱酯酶(AChE)的抑制作用。敌敌畏和灭多威对通海抗性品系AChE离体和活体内的抑制中浓度(I50)分别是敏感品系的209、26.5倍和2.21、2.16倍;敌敌畏对通海小菜蛾种群的离体和活体内抑制中时间(IT50)小于敏感品系,分别是敏感品系的0.32和0.17倍;而灭多威对通海小菜蛾种群的离体和活体内抑制中时间(IT50)则大于敏感品系,分别是敏感品系的1.37和1.74倍。

Comparison of Inhibition of Acetylcholinesterase in Susceptible and Resistant Strains of Diamondback Moth by Insecticides

The resistance level of field populations of diamondback moth collected from 3 different regions of Yunnan province was determined using leaf-dipping method and a susceptible strain maintained in the laboratory was used as control.The results indicated that different populations had different resistance levels to the insecticides.The resistance level to organophosphate insecticides varied from 1.74 to 31.1 times,to pyrethroid insecticides varied from 7.41 to 764 times and to avermectin insecticides varied from 5.60 to 4.06×10⁴ times.In vitro and in vivo AChE inhibition experiments with inhibitors of dichlorvos and methomyl showed that there were significant differences in I₅₀ (dosage of inhibiting 50% AChE activity) and IT₅₀ (time for inhibiting 50% AChE activity) between Tonghai resistant and laboratory susceptible strain.In in vivo inhibition,the AChE I₅₀ of Tonghai strain to dichlorvos and methomyl were 2.21 and 2.16 times higher than that of the susceptible strain,while in in vitro inhibition,the inhibiton were up to 209 and 26.5 times,respectively.The IT₅₀ of dichlorvos to AChE of Tonghai strain under in vitro and in vivo inhibition were 0.32 and 0.17 times as much as that of susceptible strains,respectively,while for methomyl,the inhibition increased to 1.37 and 1.74 times.