Determination of the LC50of selamectin (active principle of the antiparasitic Revolution®, Pfizer) applied on engorged female of the tickRhipicephalus sanguineus(Latreille, 1806) (Acari: Ixodidae)

Ticks have great medical and veterinary importance because they transmit several pathogens to their hosts, including humans; moreover, they cause skin lesions and favour secondary infections and blood loss. Selamectin, a macrocyclic lactone, has been used as a potent antiparasitic and is commercialized in Brazil as a product called Revolution® manufactured by Pfizer Animal Health (Guarulhos, Sao Paulo, Brazil). There is little information on the method of action of this chemical compound on tick physiology so this study presents an analysis of the toxic potential of selamectin on engorged females of the tick Rhipicephalus sanguineus. For the toxicity study of selamectin, the adult immersion test was performed, in which individual ticks were exposed to different concentrations of the chemical compound. The percentage of dead females was submitted to probit analysis to determine the median lethal concentration (LC50) of selamectin. Bioassays showed that R. sanguineus females are sensitive to the chemical co...