广东小菜蛾对苏芸金杆菌的抗性研究

A STUDY ON THE RESISTANCE OF DIAMONDBACK MOTH TO BACILLUS THURINGIENSIS IN GUANGDONG

广东省深圳、东莞、惠阳及博罗等供香港（以下简称供港）菜区小菜蛾对有机化学农药的抗性与广州内销菜区相近或稍高，对Ｂｔ杀虫剂的抗性则是供港菜区明显高于广州内销菜区。几种酶抑制剂ＴＰＰ、ＳＶ１及Ｐｂ对Ｂｔ制剂无明显增效作用，可见小菜蛾对Ｂｔ制剂的抗性与酯酶和多功能氧化酶（ＭＦＯ）的关系不大。用Ｂｔ制剂Ｄｉｐｅｌ（大宝）连代选育小菜蛾敏感品系，选育１８代，小菜蛾的抗性较选育前提高３５倍。该抗性品系小菜蛾对个别菌株Ｂｔ及巴丹、杀虫双、速灭杀了、万灵、敌敌畏等无交互抗性，而对昆虫生长调节抑制剂有轻微交互抗性。相反，用巴丹和杀虫双选育出的小菜蛾抗性品系对Ｄｉｐｅｌ仍表现敏感。抗性品系小菜蛾在无触毒条件下饲养，抗性会自然减退，但不同类杀虫剂的抗性减退速率不尽相同。

The diamondback moth (DBM), Plutella xylostella L, is one of the mostdestructive pest of crucifer crops in Guangdong Province, China. The resistance of field strains of DBM from Shenzhen (SZ) and Guangzhou (GZ) city of Guangdong Province to conventional mincrobial insecticides has been investigated. Results showed that the strains of SZ and GZ had resistance to synthetic pyrethroids,organophoshorus insecticides, carbamates as well as insect growth regulators, but onlythe strains of SZ showed resistance to microbial insecticide (B. thurhaensis)'Fenvalerate was greatly synergized with piperonyl butoxide (PB) or o,o -diethyl -ophenyl-thiophosphate (SVI). An addition of PB, SVI and TPP (triphenyl phosphate)to microbial insecticide BT resulted in no synergism, indicating that the resistant mechanism of DBM to BT does not include microsomal oxidation of MFO and esterases. Susceptible of DBM would obtain resistance to Dipel (B. thuringiensis var.Kurstaki) soon, when every generation was bred with Dipel under laboratory condition (23℃ ～ 30℃, L:D= 12:12). The LC50 of F0, F5, F12 and F18 were 30.33, 298.00,695.33 and 1077.33mg /L, respectively, the LC50 of F18 was 35.5-fold as that of F0.On the other hand, during the 20 generations of rearing without insecticide pressure,recovery of sensitivity to BT was detected, so was the recovery of sensitivity to chemical insecticides, hot the recovery of sensitivity to insect growth regulators (chlorfluazuron) and synthetic pyrethroids was very slow. Fortunately, no crossresistance was found between the chemical and microbial insecticide (BT) used.