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通过增效剂生物测定、生化分析以及钠离子通道基因ⅡS4-6cDNA片段的RT-PCR扩增,探讨了烟粉虱Bemisia tabaci(Gennadius)对拟除虫菊酯杀虫剂的抗性机理。结果表明:对于采自田间的6个烟粉虱抗性品系,磷酸三苯酯(TPP)和胡椒基丁醚(PBO)对氯氰菊酯、溴氰菊酯、氯氟氰菊酯和甲氰菊酯均有显著的增效作用,而DEM对4种拟除虫菊酯杀虫剂均无明显的增效作用。烟粉虱抗性品系的α-NA羧酸酯酶和β-NA羧酸酯酶活性分别是敏感品系的2.16～2.65倍和1.22～1.41倍,抗性品系的谷胱甘肽S转移酶活性与敏感品系没有差异,表明羧酸酯酶和多功能氧化酶在烟粉虱对拟除虫菊酯类杀虫剂的抗性中具有重要的作用,而谷胱甘肽S转移酶与抗性无关。通过RT-PCR克隆了6个烟粉虱田间抗性品系的钠离子通道结构域ⅡS4-6cDNA片段的序列(420bp),发现与敏感品系相比,有2个位点发生突变,分别为L925I突变和I917V突变,L925I突变在所有6个烟粉虱田间抗性种群中均有发生,该位点突变已被证实与拟除虫菊酯类杀虫剂密切相关,表明神经不敏感性可能是烟粉虱对拟除虫菊酯产生抗性的另一个重要因子。
The resistance mechanism of Bemisia tabaci (Gennadius) to pyrethroid insecticides was discussed by synergistic bioassay, biochemical analysis and RT-PCR amplification of ⅡS4-6 cDNA fragment of sodium ion channel. The results showed that for 6 resistant strains of B. tabaci collected from the field, the effects of triphenyl phosphate (TPP) and piperonyl butoxide (PBO) on cypermethrin, deltamethrin, cyhalothrin and fenpropathrin All had significant synergism, while DEM had no synergistic effect on the four pyrethroid insecticides. The α-NA carboxylesterase and β-NA carboxylesterase activities of resistant strains of B. tabaci were 2.16-2.65 times and 1.22-1.41 times that of the susceptible strains, respectively. The glutathione S-transferase activity of the resistant strains There was no difference with the susceptible lines, suggesting that carboxylesterases and multifunctional oxidases play an important role in the resistance of pyrethrum insecticides to B. tabaci, whereas glutathione S-transferase has nothing to do with resistance. The sequence (420 bp) of the sodium ion channel domain ⅡS4-6 cDNA of 6 whitefly field-resistant strains was cloned by RT-PCR. Two mutations were found in the field-resistant strain of B. tabaci, including L925I mutation And the I917V mutation, the L925I mutation occurred in all six populations of whitefly, and the mutation in this site has been shown to be closely related to pyrethroid insecticides, indicating that the neuronal insensitivity may be caused by whitefly Another important factor that causes resistance to pyrethroids.