Allele frequencies of acaricide resistance-associated specific nucleotide polymorphisms in Rhipicephalus microplus and Rhipicephalus decoloratus in Manicaland Zimbabwe

Abstract

Cattle ticks from the genus Rhipicephalus are hematophagous ectoparasites of great veterinary and economic importance. Currently, the main method for managing ticks and tick-borne diseases is the application of chemical acaricides. Development of resistance to these acaricides however poses a threat to the livestock sector globally, including Zimbabwe. Surveillance for acaricide resistance is essential for controlling tick populations via early intervention with an active compound to which there is no resistance in the field. In this study the allele frequencies that occur in genes linked to pyrethroid and amitraz resistance, namely the voltage-gated sodium channel and the octopamine/tyramine receptor were investigated. Specific nucleotide polymorphisms (SNPs) of Rhipicephalus spp in these genes were analysed from 18 communal dip tanks in the eastern parts of Zimbabwe. No SNPs were identified in the domain II region of the voltage-gated sodium channel gene associated with pyrethroid resistance. Resistant alleles associated with amitraz resistance in both R. decoloratus and R. microplus tick populations were observed. The level of acaricide resistance was subsequently calculated and solutions for improved acaricide resistance control are discussed.