Molecular detection of acaricide resistance in Rhipicephalus microplus in Engcobo Local Municipality Eastern Cape South Africa

Abstract

Rhipicephalus microplus transmit two important diseases of livestock in South Africa, namely Babesiosis and Anaplasmosis. As cattle still play a key role in the livelihood of rural communities in the Eastern Cape province, animal health is of utmost importance to maintain and strengthen these communities. In most rural areas of the Eastern Cape, the South African government provides free dipping of cattle with amitraz. Deltamethrin, a synthetic pyrethroid (SP), has been used as pour-on dip in a few locations where there are no functional dips. Of concern, is the growing number of global reports on the increase of acaricide resistance. Routine screening for resistance to acaricides is therefore needed. In this study we investigated allele frequencies of acaricide resistance-associated single nucleotide polymorphisms (SNPs) in R. microplus ticks from the Engcobo Local Municipality. The estimated frequencies of amitraz resistance-associated SNPs were 0.58 (at locus 1) and 0.32 (at locus 3). Resistance against formamidines (amitraz) appears to be on the rise. The published mutation in the voltage gated sodium channel (VGS) receptor gene (domain II segment 4-5 region), known to confer resistance to synthetic pyrethroids, was not found. This could be attributed to the low selection pressure against pyrethroids in the study area.