Pest and Environmental Adaptation Research Group, School of BioSciences, Bio21 Institute, The University of Melbourne, Parkville, Vic., Australia.
Melbourne Bioinformatics, The University of Melbourne, Parkville, Vic., Australia.
Mol Ecol. 2020 May;29(9):1628-1641. doi: 10.1111/mec.15430. Epub 2020 Apr 21.
Nations throughout the Indo-Pacific region use pyrethroid insecticides to control Aedes aegypti, the mosquito vector of dengue, often without knowledge of pyrethroid resistance status of the pest or origin of resistance. Two mutations (V1016G + F1534C) in the sodium channel gene (Vssc) of Ae. aegypti modify ion channel function and cause target-site resistance to pyrethroid insecticides, with a third mutation (S989P) having a potential additive effect. Of 27 possible genotypes involving these mutations, some allelic combinations are never seen whereas others predominate. Here, five allelic combinations common in Ae. aegypti from the Indo-Pacific region are described and their geographical distributions investigated using genome-wide SNP markers. We tested the hypothesis that resistance allele combinations evolved de novo in populations versus the alternative that dispersal of Ae. aegypti between populations facilitated genetic invasions of allele combinations. We used latent factor mixed-models to detect SNPs throughout the genome that showed structuring in line with resistance allele combinations and compared variation at SNPs within the Vssc gene with genome-wide variation. Mixed-models detected an array of SNPs linked to resistance allele combinations, all located within or in close proximity to the Vssc gene. Variation at SNPs within the Vssc gene was structured by resistance profile, whereas genome-wide SNPs were structured by population. These results demonstrate that alleles near to resistance mutations have been transferred between populations via linked selection. This indicates that genetic invasions have contributed to the widespread occurrence of Vssc allele combinations in Ae. aegypti in the Indo-Pacific region, pointing to undocumented mosquito invasions between countries.
整个印太地区的国家都使用拟除虫菊酯杀虫剂来控制埃及伊蚊，这种蚊子是登革热的传播媒介，但往往并不了解害虫对拟除虫菊酯的抗药性状况或抗药性的来源。埃及伊蚊钠离子通道基因（Vssc）中的两个突变（V1016G+F1534C）改变了离子通道功能，导致对拟除虫菊酯杀虫剂的靶标部位抗性，而第三个突变（S989P）具有潜在的附加效应。在涉及这些突变的 27 种可能基因型中，有些等位基因组合从未见过，而有些则占主导地位。本文描述了在印太地区埃及伊蚊中常见的五种等位基因组合，并利用全基因组 SNP 标记研究了它们的地理分布。我们检验了以下两个假设：抗性等位基因组合是在种群中从头进化而来的，而不是埃及伊蚊在种群之间扩散导致等位基因组合的遗传入侵。我们使用潜在因子混合模型来检测整个基因组中与抗性等位基因组合一致的 SNP，并且比较了 Vssc 基因内 SNP 的变异与全基因组 SNP 的变异。混合模型检测到一系列与抗性等位基因组合相关的 SNP，这些 SNP 都位于 Vssc 基因内或附近。Vssc 基因内 SNP 的变异与抗性谱有关，而全基因组 SNP 的变异与种群有关。这些结果表明，抗性突变附近的等位基因是通过连锁选择在种群之间转移的。这表明遗传入侵导致了埃及伊蚊中 Vssc 等位基因组合在印太地区的广泛存在，这表明在国家之间发生了未被记录的蚊子入侵。
