Estep Alden S, Sanscrainte Neil D, Farooq Muhammad, Lucas Keira J, Heinig Rebecca L, Norris Edmund J, Becnel James J
USDA-ARS Center for Medical Agricultural and Veterinary Entomology, Mosquito & Fly Research Unit, Gainesville, FL, USA.
Anastasia Mosquito Control District, St. Augustine, FL, USA.
Sci Rep. 2025 Mar 24;15(1):10146. doi: 10.1038/s41598-025-94738-z.
Resistance to pyrethroids is common in Aedes aegypti populations. Mutations in the voltage gated sodium channel have an influence on the insecticide resistance (IR) phenotype. In much of the Western hemisphere, two of these knockdown resistance (kdr) mutations, V1016I and F1534C, result in six kdr genotype combinations in field populations. Strong pyrethroid IR and the failure of permethrin treated uniforms have been linked to the presence of the homozygous double kdr genotype (IICC) but the effects of the other five kdr combinations have not been rigorously examined, particularly with regard to operational efficacy. To better understand the impacts of these common kdr genotypes, we isolated three kdr haplotypes (VF, VC, & IC) from a field collected strain to produce six Ae. aegypti isoline strains with all the common V1016I/F1534C kdr genotypes. We then characterized the effects of these genotypes by CDC bottle bioassay and topical application and found increasing resistance to permethrin and deltamethrin as the number of IC haplotypes increased. Neither enzymatic activity nor malathion resistance increased with increasing pyrethroid resistance. We then assessed the operational impacts of these kdr genotypes. Field and wind tunnel spray of a pyrethrin formulation showed that even moderate resistance could significantly reduce knockdown and mortality. Studies with a synergized pyrethroid formulation showed effective recovery of mortality against all genotypes except for the IICC. In human bite studies, one or two IC haplotypes compromised the efficacy of permethrin treated fabrics. This study demonstrates that kdr mutations have distinct phenotypic effects in both the laboratory and operational interventions, and that the strength of pyrethroid resistance varies with the number of IC haplotypes present. Assessing kdr genotype is therefore critical for understanding IR in Ae. aegypti.
在埃及伊蚊种群中，对拟除虫菊酯产生抗性的情况很常见。电压门控钠通道的突变会影响杀虫剂抗性（IR）表型。在西半球的大部分地区，这两种击倒抗性（kdr）突变，即V1016I和F1534C，在野外种群中产生了六种kdr基因型组合。强烈的拟除虫菊酯抗性以及经氯菊酯处理的制服失效与纯合双kdr基因型（IICC）的存在有关，但其他五种kdr组合的影响尚未得到严格研究，特别是在操作效果方面。为了更好地理解这些常见kdr基因型的影响，我们从一个野外采集的品系中分离出三种kdr单倍型（VF、VC和IC），以产生六种具有所有常见V1016I/F1534C kdr基因型的埃及伊蚊近交系。然后，我们通过疾控中心瓶试生物测定法和局部应用来表征这些基因型的影响，发现随着IC单倍型数量的增加，对氯菊酯和溴氰菊酯的抗性增强。酶活性和对马拉硫磷的抗性均未随拟除虫菊酯抗性的增加而增加。然后，我们评估了这些kdr基因型的操作影响。对除虫菊酯制剂进行的野外喷雾和风洞喷雾表明，即使是中等抗性也会显著降低击倒率和死亡率。对增效拟除虫菊酯制剂的研究表明，除IICC外，对所有基因型的死亡率均有有效恢复。在人体叮咬研究中，一两个IC单倍型会损害经氯菊酯处理织物的功效。这项研究表明，kdr突变在实验室和实际干预中都有不同的表型效应，并且拟除虫菊酯抗性的强度随IC单倍型数量的增加而变化。因此，评估kdr基因型对于了解埃及伊蚊的杀虫剂抗性至关重要。
