Acaricide Resistance of Rhipicephalus decoloratus Ticks Collected from Communal Grazing Cattle in the North-Eastern Region of the Eastern Cape Province, South Africa

Yawa M, Nyangiwe N, Jaja IF, Mafuru CM and Kadzere CT

Published on: 2021-07-23

Abstract

Amongst other tick species in the world, Rhipicephalus decoloratus ticks are one of the most widely distributed and considered as the most important external ectoparasite to livestock, particularly in cattle and can be resistant to almost every application of acaricide chemical. This study aimed to determine acaricide resistance of R. decoloratus collected from grazing cattle between November 2018 and May 2019 at Elundini, Senqu and Walter Sisulu Local Municipalities in the north-eastern region of the Eastern Cape Province (ECP). A sample of 20–30 adult engorged female R. decoloratus ticks were collected from at least 10 randomly selected cattle at each dip tank and placed into plastic collection labelled bottles containing absorbent paper and with perforated lids at constant room temperature of ±28°C and >70 % relative humidity until resistance testing commences. The Shaw Larval Immersion Test (SLIT) method was used to determine R. decoloratus larvae resistance from various acaricides concentration levels of amidines, organophosphate and synthetic pyrethroids. The SLIT was only performed on the R. decoloratus larvae as engorged R. microplus ticks could not meet the required sample size for resistance testing. The resistance testing results showed no resistance to amidines was detected at any of the localities and with no resistance to organophosphate at Senqu region. This study further documented an alarming resistance development of the larvae towards all the acaricide used for testing and more especial to organophosphate chemical. During tick collections, R. microplus was also found although it did not meet sample size for resistances testing thus, this necessitate monitory study on the distribution of R. microplus and extent of tick resistance towards the commonly used acaricides.