不同杀虫剂选育对家蝇抗药性水平及kdr基因频率的影响

采用杀虫剂（溴氰菊酯和甲基嘧啶磷）筛选及不接触药物自然衰退的方法，研究了家蝇Musca domestica氯氟氰菊酯高抗品系(Cyh-R)对杀虫剂的抗性变化，探讨蝇类抗药性治理的方法。用点滴法测定氯氟氰菊酯对不同家蝇品系的毒力，比较抗药性的变化，结合特异性等位基因PCR扩增（PASA）技术检测了不同家蝇品系的kdr基因频率，探讨kdr基因频率与抗性水平之间的关系。结果表明:甲基嘧啶磷筛选后，氯氟氰菊酯对第2~8代Cyh-R品系的LD₅₀呈递减趋势，从F₀的2.8434 μg/蝇降为F₈的0.4404 μg/蝇，但第8~18代Cyh-R品系的LD₅₀呈逐代递增趋势；溴氰菊酯筛选后，氯氟氰菊酯对Cyh-R品系第2~16代的LD₅₀呈上升趋势，从F₀的2.8434 μg/蝇升至F₁₆的24.3249 μg/蝇；表明了施用有机磷杀虫剂可降低其对氯氟氰菊酯的抗药性，而施用拟除虫菊酯药剂则有助于其对氯氟氰菊酯抗药性的增长；不使用任何杀虫剂也能降低其对氯氟氰菊酯的抗药性，但下降速率低于甲基嘧啶磷。PASA技术检测表明Cyh-R品系的kdr抗性基因频率为88.8%，不经过任何药剂筛选其kdr抗性基因频率下降程度最大，达到69.7%；甲基嘧啶磷筛选后其结果降为78.8%，而经溴氰菊酯筛选后kdr抗性基因频率则明显升高，达到98.9%。通过对kdr抗性基因频率和抗性水平进行相关和回归分析表明kdr抗性基因频率与家蝇对氯氟氰菊酯的LD₅₀呈对数关系，即LD₅₀值高的品系其kdr抗性基因频率相应的也较高。建议在家蝇防治中考虑轮换用药。

Effects of selection by several insecticides on resistance levels and kdr allele frequency of housefly, Musca domestica (Diptera: Muscidae)

The high-level resistant strain (Cyh-R) of Musca domestica to cyhalothrin was selected by using deltamethrin and pirimiphos-methyl to study the effects of several insecticides on Cyh-R housefly strain and explore the methods of housefly resistance management. The knockdown resistance (kdr) allele frequencies of these housefly strains were detected with PCR amplification of specific allele （PASA）technology in order to study the relationship of kdr allele frequency and resistance level. The results showed that the toxicity of cyhalothrin to Cyh-R strain after selection with pirimiphos-methyl tended to decline. The LD₅₀ value dropped from 2.8434 μg/housefly in F₀ to 0.4404 μg/housefly in F₈. However, the toxicity of cyhalothrin to Cyh-R strain after selected with deltamethrin tended to rise. The LD₅₀ value increased from 2.8434 μg/housefly in F₀ to 24.3249 μg/housefly in F₁₆. These results suggest that the high-level resistance of housefly strain to cyhalothrin could decline with the application of organophosphate pesticide or without insecticides, while increase with the application of pyrethroids. The results of PASA showed that kdr allele frequency of Cyh-R strain was 88.8%. The kdr allele frequency decreased to 69.7% without insecticide selection and 78.8% after pirimiphos-methyl selection, respectively, while increased greatly after deltamethrin selection, amounting to 98.9%. The results further indicate that there is a positive correlation between kdr allele frequency and LD₅₀ value of cyhalothrin.