Department of Entomology, Pennsylvania State University, University Park, PA, USA.
Department of Environmental Sciences, Emory University, Atlanta, GA, USA.
Parasit Vectors. 2019 Jan 9;12(1):20. doi: 10.1186/s13071-018-3275-9.
As resistance to insecticides increases in disease vectors, it has become exceedingly important to monitor populations for susceptibility. Most studies of field populations of Aedes aegypti have largely characterized resistance patterns at the spatial scale of the city or country, which may not be completely informative given that insecticide application occurs at the scale of the house or city block. Phenotypic resistance to pyrethroids dominates in Ae. aegypti, and it has been partially explained by mutations in the voltage-gated sodium channel gene. Here, we assess community-level patterns of four knockdown resistance (kdr) haplotypes (C1534/I1016, F1534/I1016, C1534/V1016 and F1534/V1016) in Ae. aegypti in 24 randomly chosen city blocks from a city in Yucatán State, Mexico, during both the dry and wet season and over two years.
Three of the four haplotypes, C1534/I1016, C1534/V1016 and F1534/V1016 were heterogeneous between city blocks at all four sampling time points, and the double mutant haplotype, C1534/I1016, showed a significant increase following the wet season. The F1534/I1016 haplotype was rarely detected, similar to other studies. However, when haplotype frequencies were aggregated to a coarser spatial scale, the differences in space and time were obscured.
Our results provide empirical evidence that the selection of kdr alleles is occurring at fine spatial scales, indicating that future studies should include this scale to better understand evolutionary processes of resistance in natural populations.
随着病媒昆虫对杀虫剂的抗药性不断增强，监测其种群的敏感性变得极为重要。大多数关于埃及伊蚊野外种群的研究主要在城市或国家的空间尺度上描述了抗药性模式，但鉴于杀虫剂的应用发生在房屋或城市街区的尺度上，这种模式可能并不完全具有信息性。拟除虫菊酯的表型抗性在埃及伊蚊中占主导地位，部分原因是电压门控钠离子通道基因的突变。在这里，我们评估了在墨西哥尤卡坦州一个城市的 24 个随机选择的城市街区中，埃及伊蚊在旱季和雨季以及两年内的四个击倒抗性（kdr）单倍型（C1534/I1016、F1534/I1016、C1534/V1016 和 F1534/V1016）的社区水平模式。
在所有四个采样时间点，四个单倍型中的三个（C1534/I1016、C1534/V1016 和 F1534/V1016）在城市街区之间存在异质性，双突变单倍型 C1534/I1016 在雨季后显著增加。F1534/I1016 单倍型很少被检测到，与其他研究类似。然而，当单倍型频率聚合到更粗糙的空间尺度时，空间和时间的差异就被掩盖了。
我们的研究结果提供了经验证据，表明 kdr 等位基因的选择正在发生在精细的空间尺度上，这表明未来的研究应该包括这一尺度，以更好地理解自然种群中抗性的进化过程。
