EVALUATION OF THE POTENTIAL OF SYSTEMIC SLOW RELEASE CHEMICAL TREATMENTS FOR CONTROL OF THE CATTLE TICK(BOOPHILUS MICROPLUS)USING IVERMECTIN

Abstract

SUMMARY Stall and field trials with cattle infested with various acaricide‐resistant strains of cattle tick, have demonstrated the potential of ivermectin as a systemic tickicide. A dosage of 200 μg/kg, administered subcutaneously to animals naturally infested in the field, gave satisfactory tick control for 21 days, after an initial lag period of 2 days immediately following treatment, during which significant numbers of ticks survived. Daily subcutaneous treatments, administered so as to simulate slow release, indicated that a dosage of 15 μg/skg/day should give complete tick control if the chemical could be released continuously from a subcutaneous implant. The potency of ivermectin, assessed by in vitro tests against engorged adults, suggests that the tickicidal activity could be associated with the parent compound per se rather than a metabolite.