Li Andrew Y, Guerrero Felix D, Almazán Garcia Consuelo, George John E
USDA-ARS, Knipling-Bushland U.S. Livestock Insects Research Laboratory, 2700 Fredricksburg Road, Kerrville, TX 78028, USA.
J Med Entomol. 2003 Nov;40(6):942-9. doi: 10.1603/0022-2585-40.6.942.
A field survey was conducted in 2001 to evaluate resistance to pyrethroid and organophosphate (OP) insecticides on horn flies, Hematobia irritans irritans (L.), from seven ranches in the state of Tamaulipas, Mexico, and from three locations in central Texas. Filter papers impregnated with either technical permethrin or diazinon were used to measure the levels of resistance to pyrethroids and OPs. A multiplex polymerase chain reaction (PCR) assay was used on individual horn flies from these field populations to detect the presence of the kdr and super-kdr alleles associated with pyrethroid resistance, and a mutated alphaE7 esterase allele associated with OP resistance. Relative to a susceptible laboratory (Kerrville) strain, horn flies from Mexico exhibited 5.1- to 28.3-fold resistance to permethrin at the LC50, and 23.8- to 136-fold resistance at the LC90. Horn flies from Texas ranches exhibited only two- to five-fold resistance. All field populations of the horn fly were highly susceptible to diazinon, and no mutant alphaE7 esterase alleles were detected. The super-kdr allele was found only in a single fly from a ranch in Mexico. Results of PCR assays showed that the kdr allele was present at various frequencies in field populations of horn flies. A gender-related bias in distribution of kdr genotypes was found in horn flies from Mexico, but not in horn flies from Texas. The overall kdr allelic frequencies in horn flies from Mexico were 23.2-37.8% higher in females than in males. Regression analysis revealed a significant correlation between kdr allelic frequencies and the levels of knockdown resistance to permethrin among the horn fly populations studied. The results validate the role of the PCR-based molecular assay as a diagnostic tool in monitoring resistance to pyrethroids and also provide useful information on population genetics of horn fly resistance to pyrethroids and OPs.
2001年开展了一项实地调查，以评估墨西哥塔毛利帕斯州七个牧场以及得克萨斯州中部三个地点的角蝇（嗜人血蝇指名亚种，Hematobia irritans irritans (L.)）对拟除虫菊酯和有机磷酸酯（OP）类杀虫剂的抗性。用含有氯菊酯原药或二嗪农的滤纸来测定对角蝇对拟除虫菊酯和OP类杀虫剂的抗性水平。对这些野外种群的单个角蝇进行多重聚合酶链反应（PCR）分析，以检测与拟除虫菊酯抗性相关的击倒抗性（kdr）和超级击倒抗性（super-kdr）等位基因，以及与OP抗性相关的突变αE7酯酶等位基因。相对于一个敏感的实验室（克尔维尔）品系，来自墨西哥的角蝇在LC50时对氯菊酯表现出5.1至28.3倍的抗性，在LC90时表现出23.8至136倍的抗性。来自得克萨斯州牧场的角蝇仅表现出2至5倍的抗性。所有野外种群的角蝇对二嗪农都高度敏感，未检测到突变的αE7酯酶等位基因。超级kdr等位基因仅在墨西哥一个牧场的一只角蝇中发现。PCR分析结果表明，kdr等位基因在角蝇野外种群中以不同频率存在。在来自墨西哥的角蝇中发现了kdr基因型分布的性别相关偏差，但在来自得克萨斯州的角蝇中未发现。来自墨西哥的角蝇中，雌性的总体kdr等位基因频率比雄性高23.2%至37.8%。回归分析显示，在所研究的角蝇种群中，kdr等位基因频率与对氯菊酯的击倒抗性水平之间存在显著相关性。这些结果证实了基于PCR的分子分析作为监测拟除虫菊酯抗性的诊断工具的作用，也为角蝇对拟除虫菊酯和OP类杀虫剂抗性的种群遗传学提供了有用信息。
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