Efficacy of orally administered ivermectin against larval stages of bot fly (Cephenemyia stimulator) in roe deer

The aim of this study was to determine the efficacy of a two-day winter administration of ivermectin (0.30 mg.kg*[-1] body mass per day) against larval stages of Cephenemyia stimulator in roe deer. The study consisted of two phases: one 3-year and two 1.5-year periods. The number of larvae in roebuck, doe and roe kid heads (a total of 283 animals) were determined. The prevalence and intensity of infestation before and after ivermectin administration were calculated. It was demonstrated that drug reduces markedly spring and summer values of prevalence as well as intensity of infestation. However, after the summer period, prevalence and intensity of infestation began to rise conspicuously again. Biological properties of the causative agent of this parasitosis call for annual treatment of game in independent hunting grounds or their smaller complexes.