[Tick resistance to pesticides in the R.S.A. - some observations (author's transl)].

Observations on the screening for resistance against acaricides in both larvae and adults of tick species commonly found on cattly in South Africa, have shown that widespread resistance of varying degrees occurs in strains of all these species against compounds of the arsenical, organochlorine and organophosphorous groups. With few exceptions the degree of resistance is of a low order and probably indicative of selection at the low acaricide concentrations generally used by stockowners. The distribution of less susceptible and resistant strains is patchy, and fully susceptible strains are found in the same areas.