tetrachlorvinphos and Lice-Infestations

Polymer matrix ear tags containing 13.7% w/w tetrachlorvinphos or 8.5% w/w cypermethrin were applied to Merino wethers infested with lice and carrying two months wool. The cypermethrin tags reduced louse numbers by a maximum of 89% in comparison to controls at 16 weeks after treatment and by 85% at the conclusion of the experiment 38 weeks after application. Lice were not eradicated from any sheep. The number of lice counted on sheep treated with tetrachlorvinphos-impregnated tags was not significantly different from controls.

Topics: Analysis of Variance; Animals; Delayed-Action Preparations; Insecticides; Lice Infestations; Male; Pyrethrins; Sheep; Sheep Diseases; Tetrachlorvinphos