菜青虫抗药性的调查与研究

我国菜青虫抗药性的形成大体上可分为两个阶段,六十年代末为滴滴涕抗药性高峰期,停用滴滴涕后,其抗性有所衰退。七十年代中期进入敌百虫抗性高峰期。目前的菜青虫多为敌百虫-滴滴涕联合抗性种群。敌杀死对敌百虫表现出正交互抗性,滴滴涕与敌百虫之间未表现明显的交互抗性,而辛硫磷对敌百虫却表现负交互抗性现象。用33种杀虫剂对联合抗性菜青虫种群做了田间药效试验及毒力测定,按药效将其分为六级:属特效、高效和有效级的药剂共有22种;属低效,基本无效和无效级的药剂共有11种。沙蚕毒素类药剂杀虫环对菜青虫药效高,对菜青虫体内的某些种类的寄生蜂影响较小,有利于协调防治。

A STUDY OF RESISTANCE OF CABBAGE WORM (PIERIS RAPAE L.) TO INSECTICIDES

A study of resistance of cabbage worm (Pieris rapae L.) to insecti-cides had been carried out during 1971~1982.In China,two stages can be found in the development of resistance of cabbage worm to insecticides: 1)the highest resistance to DDT appeared at the end of 1960s,however, it was declined after 1970 as DDT was no longer used for controlling this pest from that time on;2)in the middle of 1970s its resistance to trichlorphon increased thousands of times and reached its maximum.It was also found that the resistance of this pest in suburbs of cities is much higher than that in the coundryside;and in the South is much higher than in the North as a whole.Recently the populations of cabbage worm in most parts of China have obtained joint-resistance to both trich-lorphon and DDT.The cabage worm which is resistant totrichlorphon showed positive cross-resistance to deltamethrin and negative cross-resis-tance to phoxim.But cross-resistance between trichlorphon and DDT was not observed.The toxicity and efficacy of 33 insecticides to the pest were determined in Taian Shandong.As a result,these insecticides can be classified into 6 grades,namely;most effective,highly effective,effective,low effective,relatively ineffective,and entirely ineffective.The first three grades include 22 insecticides (table 3),which are all valu-able for controlling the resistant cabbage worm.