DeLisi N, Ottea J, Healy K
Department of Entomology, Louisiana State University.
J Econ Entomol. 2017 Dec 5;110(6):2562-2567. doi: 10.1093/jee/tox244.
Mosquito control districts conduct rigorous insecticide treatments against both larval and adult Culex quinquefasciatus Say (Diptera: Culicidae), the primary vector of West Nile virus in the southern United States. However, the development of resistant populations of Cx. quinquefasciatus in response to extensive larvicide or adulticide applications has been demonstrated repeatedly across the world. Examining changes in insecticide susceptibility in treated field areas can help inform mosquito control districts as to whether or not their treatments remain effective. We hypothesized that frequent insecticide applications for the control of mosquitoes in East Baton Rouge Parish, Louisiana, lowered susceptibility of wild Cx. quinquefasciatus to larvicides. Larvicide susceptibility was measured using Lysinibacillus sphaericus, spinosad, and temephos in populations of Cx. quinquefasciatus sampled from sites in three Parishes where frequencies of insecticide applications varied, and frequencies of resistance were measured relative to a susceptible reference colony. Susceptibility to these larvicides was widespread, although fourfold resistance to the organophosphate temephos was detected at one site in East Baton Rouge Parish in the spring of 2016, which increased to eightfold resistance by the end of the mosquito season. Activities of esterases were found to be elevated in wild, temephos-resistant mosquitoes, indicating the potential role of these enzymes as a mechanism of resistance. The results of this study provide a baseline of comparison for future measurements of susceptibility in Cx. quinquefasciatus in Louisiana, and may help inform local mosquito control districts as to the effectiveness and sustainability of their insecticide programs.
蚊虫控制区对美国南部西尼罗河病毒的主要传播媒介——致倦库蚊（双翅目：蚊科）的幼虫和成虫进行严格的杀虫剂处理。然而，在全球范围内，因大量使用杀幼虫剂或杀虫剂，致倦库蚊抗性种群的发展已被反复证实。检测处理过的野外区域中杀虫剂敏感性的变化，有助于告知蚊虫控制区其处理措施是否仍然有效。我们假设，在路易斯安那州东巴吞鲁日教区频繁使用杀虫剂控制蚊虫，会降低野生致倦库蚊对杀幼虫剂的敏感性。使用球形赖氨酸芽孢杆菌、多杀菌素和双硫磷，对从三个教区不同杀虫剂使用频率地点采集的致倦库蚊种群进行杀幼虫剂敏感性测定，并相对于一个敏感参考群体测定抗性频率。对这些杀幼虫剂的敏感性普遍存在，尽管2016年春季在东巴吞鲁日教区的一个地点检测到对有机磷双硫磷有四倍抗性，到蚊虫季节结束时增加到八倍抗性。在野生的、对双硫磷有抗性的蚊子中发现酯酶活性升高，表明这些酶作为抗性机制的潜在作用。本研究结果为路易斯安那州未来致倦库蚊敏感性测量提供了比较基线，并可能有助于告知当地蚊虫控制区其杀虫剂计划的有效性和可持续性。
