AbstractBackgroundThe tickRhipicephalus sanguineusis the species with the largest worldwide distribution and is proven to be involved in the transmission of pathogens such asBabesia canis,Ehrlichia canis,Coxiella burnetii,Rickettsia ricketsii,Rickettsia conorii, among others. Studies have demonstrated acquisition of resistance to some of the active principles used in commercial formulations of acaricides.Tagetes patula(Asteraceae) is a plant with highlighted economic and commercial importance due to the production of secondary metabolites with insecticide and acaricide potential, mainly flavonoids, thiophenes and terpenes.MethodsThein vitroacaricide action of the ethanolic 70% extract from aerial parts ofT. patula, obtained by percolation, was evaluated against larvae and engorged adult females ofRhipicephalus sanguineusby immersion test for 5 minutes. The chemical characterization of this extract was done by liquid chromatography coupled with mass spectrometry (LC-MS), using direct injection of sample.ResultsDespiteT. patulanot proving lethal to adults in any of the concentrations tested, at 50.0 mg/mL oviposition rate decreased by 21.5% and eliminated 99.78% of the larvae. Also it was determined that the best results were obtained with 5 minutes of immersion. From the chromatographic analysis twelveO-glycosylated flavonoids were identified.ConclusionsThis is the first report on the acaricidal activity ofT. patulaextract againstRh. sanguineus. If we consider the application of the product in the environment, we could completely eliminate the larval stage of development of the ixodidRh. sanguineus.