Center for Evolution and Medicine, School of Life Sciences, Arizona State University.
United States Department of Agriculture, Agricultural Research Service, Center for Medical, Agricultural and Veterinary Entomology.
J Vis Exp. 2022 Jan 19(179). doi: 10.3791/63391.
The continued use of insecticides for public health and agriculture has led to widespread insecticide resistance and hampering of control methods. Insecticide resistance surveillance of mosquito populations is typically done through Centers for Disease Control and Prevention (CDC) bottle bioassays or World Health Organization (WHO) tube tests. However, these methods can result in a high degree of variability in mortality data due to variable insecticide contact with the insect, the relatively small numbers of organisms tested, extensive variation in mass between populations, and constantly changing environmental conditions, leading to variable outcomes. This paper presents the topical application bioassay, adapted as a high-throughput phenotypic bioassay for both mosquitoes and fruit flies, to test large numbers of insects along a range of insecticide concentrations. This assay 1) ensures consistent treatment and insecticide contact with every organism, 2) produces highly specific dose-response curves that account for differences in average mass between strains and sexes (which is particularly important for field-collected organisms), and 3) allows for the calculation of statistically rigorous median lethal doses (LD50), which are necessary for resistance ratio comparisons-an alternative surveillance approach from diagnostic dose mortality, which is also used for larvicide resistance surveillance. This assay will be a complementary tool for accurately phenotyping mosquito populations and, as illustrated using fruit flies, is easily adaptable for use with other insects. We argue that this assay will help fill the gap between genotypic and phenotypic insecticide resistance in multiple insect species.
持续使用杀虫剂来进行公共卫生和农业工作，导致了广泛的杀虫剂耐药性，并且阻碍了控制方法的实施。蚊虫种群的杀虫剂耐药性监测通常通过疾病控制与预防中心（CDC）瓶生物测定或世界卫生组织（WHO）管测试进行。然而，由于杀虫剂与昆虫的接触、测试的生物数量相对较少、种群之间的质量差异广泛以及不断变化的环境条件等因素，这些方法可能导致死亡率数据存在高度可变性，从而导致结果不一致。本文介绍了一种经改良的体表应用生物测定法，将其作为一种针对蚊子和果蝇的高通量表型生物测定法，可用于测试大量昆虫在一系列杀虫剂浓度下的情况。该测定法：1）确保每只昆虫都能得到一致的处理和杀虫剂接触；2）产生高度特异性的剂量反应曲线，以解释不同品系和性别的平均质量差异（这对于野外采集的生物尤为重要）；3）可计算出统计学上严格的半数致死剂量（LD50），这对于抗性比比较是必要的，这是一种替代诊断剂量死亡率的监测方法，也用于杀幼虫剂耐药性监测。这种测定法将成为准确表型分析蚊虫种群的一种补充工具，并且正如使用果蝇所说明的那样，它很容易适应于其他昆虫。我们认为，这种测定法将有助于填补多种昆虫的基因型和表型杀虫剂耐药性之间的空白。
