Mortality of Culicoides brevitarsis fed on cattle treated with ivermectin

Adult female Culicoides brevitarsis Kieffer, important vectors of arboviruses affecting livestock in Australia, were fed on penned Hereford yearling cattle which had been given a single subcutaneous injection of ivermectin at a dose of 200 mcg/kg. The mean mortality of engorged females 48 hr after feeding on the treated cattle was 99% for 10 days posttreatment and in excess of 40% for 18 days posttreatment. Based on these results, it appears that ivermectin administered subcutaneously could be a useful tool for the control of Culicoides-transmitted diseases and would provide an attractive alternative to "slaughter out" programs in the case of a major exotic disease threat.