USDA-ARS, Knipling-Bushland U.S. Livestock Insects Research Laboratory, 2700 Fredericksburg Rd., Kerrville, TX 78028, USA.
J Econ Entomol. 2011 Feb;104(1):250-7. doi: 10.1603/ec10307.
The insect sodium channel is of particular interest for evaluating resistance to pyrethroids because it is the target molecule for this major class of neurotoxic insecticides. The stable fly, Stomoxys calcitrans (L.) (Diptera: Muscidae), sodium channel coding sequence representing domains IS6 through IVS6 was isolated, and the sequence encoding domain II was compared among individuals of a laboratory strain selected for resistance to permethrin and the unselected, parental generation. A point mutation resulting in a leucine-to-histidine amino acid change was identified (Leul014His), and its location corresponded with that observed for knockdown resistance (kdr) mutations in other insects. As a result, the allele was designated kdr-his. A molecular assay was developed to assess the frequency of this mutation in genomic DNA of individual stable flies from the laboratory selections, which provided further evidence that the kdr-his allele accounts for the observed level ofpermethrin resistance in the selected strain. The assay was then used to evaluate the frequency of the mutation from five field-collected populations originating from three horse farms near Ocala, FL; one horse farm near Gainesville, FL; and one dairy farm near Hague, FL. Frequency of the kdr-his allele ranged from 0.46 to 0.78, supporting further investigation of allele prevalence throughout the stable fly season and in response to field insecticide application.
昆虫钠离子通道是评估对拟除虫菊酯类杀虫剂抗性的特别关注点，因为它是此类主要的神经毒杀虫剂的靶标分子。稳定蝇，Stomoxys calcitrans（L.）（双翅目：蝇科）钠离子通道编码序列代表 IS6 至 IVS6 结构域，该序列编码结构域 II 在对氯菊酯具有抗性的实验室选择株和未选择的亲本代个体之间进行了比较。鉴定出导致亮氨酸到组氨酸氨基酸变化的点突变（Leul014His），其位置与其他昆虫中观察到的击倒抗性（kdr）突变一致。因此，该等位基因被命名为 kdr-his。开发了一种分子测定法来评估实验室选择个体稳定蝇基因组 DNA 中该突变的频率，这进一步证明 kdr-his 等位基因解释了所选菌株中观察到的氯菊酯抗性水平。然后，该测定法用于评估来自佛罗里达州奥卡拉附近的三个马场、佛罗里达州盖恩斯维尔附近的一个马场和佛罗里达州 Hague 附近的一个奶牛场的五个野外采集群体中该突变的频率。kdr-his 等位基因的频率范围为 0.46 至 0.78，支持进一步调查整个稳定蝇季节和对田间杀虫剂应用的等位基因流行率。
