Resistance of cattle tick (Boophilus microplus (Canestrini)) to Benzene Hexachloride.

Abstract

A strain of the cattle tick from central Queensland shows a degree of resistance to BHC which makes it impossible to control under ordinary dipping routine with the recommended concentration of 500 parts per million gamma- BHC. Laboratory tests showed that the concentration of gamma-BHC required to prevent deposition of viable eggs by 50 per cent. of females of this strain was 185 times higher than the corresponding value for female ticks of a strain which had never been treated with BHC. A similar difference in degree of resistance between larvae of the two strains was also demonstrated by laboratory toxicity tests, although in absolute terms the tolerance of larvae was much lower than that of engorged females. The BHC-resistant strain was also found to exhibit a tolerance to other acaricides.