Acaricide resistance in the blue cattle tick in South Africa; A comparison of three assays for determining tick resistance

Abstract

The susceptibility of engorged females and larvae of Boophilus decoloratus ticks,- collected from cattle on breeding farms in Kwazula Natal, Eastern Cape and Limpopo provinces in South Africa-, for amitraz, cypermetrin and chlorfenvinphos. Was examined by means of the Adult Immersion test (AIT), the Shaw Larval Immersion Test (SLIT) and the Larval Packet Test (LPT). The results indicated resistance of Boophilus ticks to cypermetrin on all nine farms examined. On six farms ticks had developed resistance against amitraz demonstrated by all three tests procedures. On one farm ticks were still susceptible for amitraz in all tests, whereas in 2 remaining farms tests were not in agreement. Furthermore ticks were found susceptible for chlorfinvenphos on three farms in all three tests, whereas in 5 farms showed they appeared to be resistant. In general the results obtained with the different tests were in agreement.