Multiple mutations in the para-sodium channel gene are associated with pyrethroid resistance in Rhipicephalus microplus from the United States and Mexico

摘要: Acaricide resistant Rhipicephalus microplus populations have become a major problem for many cattle producing areas of the world. Pyrethroid resistance in arthropods is typically associated with mutations domains I, II, III, and IV voltage-gated sodium channel genes. In R. microplus, known include domain II change (C190A) from Australia, Africa, South America III mutation (T2134A) that only occurs Mexico U.S. We investigated pyrethroid fever ticks Texas by estimating levels field-collected using larval packet discriminating dose (DD) assays identifying single nucleotide polymorphisms (SNPs) para-sodium gene resistance. then developed qPCR three SNPs screened larger set 1,488 ticks, representing 77 field collections four laboratory strains, SNP frequency. detected 21 68 six nine collections. expected to identify at high frequency; however, we found it A much more common (detected 19 collections) was C190A mutation, which has never before been reported North America. also discovered novel (T170C) ten two The T170C transition previously extreme (super-knockdown resistance) insects. significant correlation (r = 0.81) between proportion individuals carried any percent survivorship F1 larvae these DD assays. This relationship accurately predicted simple linear regression model (R2 0.6635). These findings demonstrate multiple independently associate likely consequence human-induced selection.