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.
