Efficacy of fipronil (1.0 mg/kg) against Rhipicephalus (Boophilus) microplus strains resistant to ivermectin (0.63 mg/kg).

The present study aimed to evaluate the efficacy of fipronil (1 mg/kg) against three strains of ivermectin-resistant Rhipicephalus (Boophilus) microplus (R. (B.) microplus), naturally infesting cattle from different states of Brazil.