Susceptibility of ticks to acaricides in Zambia

The susceptibility of some Zambian ticks to dieldrin, dioxathion, dimethoate and chlorfenvinphos was determined on two- to three-week-old larvae of Amblyomma variegatum, Boophilus decoloratus, B. microplus, Rhipicephalus appendiculatus, R. e. evertsi and a member of the R. pravus group. Some strains of B. decoloratus and R. appendiculatus were resistant to dieldrin, dioxathion and dimethoate and some R. e. evertsi were resistant to dieldrin and dioxathion. A single strain of an R. pravus group tick was resistant to dioxathion and one out of four strains of A. variegatum was resistant to dieldrin.