淡色库蚊酯酶等位基因及其在自然种群中的频率分布

酯酶基因扩增所产生的酯酶活性升高是库蚊Culex pipiens对有机磷杀虫剂抗性的主要机理之一。采用分子杂交技术和限制性酶切片段长度多态性(RFLP)分析，已鉴定出多种酯酶等位基因类型。该文通过酯酶基因特异性片段的PCR扩增及扩增片段的酶切片段分析，对淡色库蚊Culex pipiens pallens四种有机磷抗性品系的酯酶等位基因进行分型，并测定分析自然种群中不同酶型的频率分布。研究结果表明：PCR分型方法具有快速、准确的特点。不同的有机磷杀虫剂对酯酶等位基因具有明显的选择作用。双硫磷品系为B₁型；毒死蜱和敌百虫品系为B₂型；马拉硫磷品系为B₁型和B₁/B₂杂合型。不同地区采集的种群表现出不同的酶型频率分布。该文就杀虫剂对酯酶等位基因选择作用及自然种群的酶型频率分布进行了讨论。

PCR IDENTIFICATION AND PROBABILITY OF AMPLIFIED ESTERASE GENES IN CULEX PIPIENS PALLENS

Organophosphate insecticide (OP) resistance in mosquitoes of Culex pipiens complex has been shown to be correlated with the increase in esterase activity resulting from overproduction of the esterase due to amplification of the corresponding structural gene. Several esterase B loci have been identified with Southern hybridization and restriction fragment length polymorphism (RFLP). In this paper, esterase B loci in four OP resistant strains of Culex pipiens pallens were identified with the restriction analysis of PCR fragments. The results indicate that various esterase loci have different selective advantages under different OP pressures. B 1 gene was amplified in temephos resistant strain, and B 2 gene was amplified in trichlorphon and chlorpyrifos resistant strains. The hybridzygote of B 1 and B 2 genes was detected in the malathion resistant strain. Different natural populations of C.pipiens pallens have different probability of B gene distribution. These results are discussed in relation to the selective advantage of esterase genes to OP pressure and mosquito control strategies.