Haemaphysalis concinna (Acari: Ixodida): persistent efficacy of selamectin in Angora rabbits under laboratory conditions.

In the present study, the persistent efficacy of selamectin (SEL) in Angora rabbits infested with Haemaphysalis concinna was observed. SEL (6 mg/kg) was administered to rabbits with a single topical application. Eighteen Angora rabbits were randomly allocated to three groups of six rabbits each. At days 1, 8, 15, 22, and 29 following SEL administration, rabbits were inoculated with larval, nymphal, and adult ticks and were then observed for a period of 7 days. The cumulative reduction rates at days 1, 8, 15, 22, and 29 for dead ticks were 100%, 100%, 100%, 95.0%, and 76.7%, respectively, for larvae; 100%, 100%, 100%, 85.0%, and 65.0%, respectively, for nymphs; and 100%, 95.0%, 85.0%, 60.0%, and 45.0%, respectively, for adults. The cumulative reduction rates for larvae in untreated Angora rabbits (controls) were 3.3%, 1.7%, 3.3%, 5.0%, and 5.0%, respectively. There was no reduction of nymphs and adults in untreated Angora rabbits (controls). The reduction rates for larvae, nymphs, and adults were significantly higher for Angora rabbits inoculated with SEL than the controls (P < 0.001).