title: [In vitro analysis of amitraz efficacy against Rhipicephalus (Boophilus) microplus (Canestrini, 1887) populations of southern region of Rio Grande do Sul state].
abstract: Commercial formulation of the amitraz is the most used acaricide in the southern region of Rio Grande do Sul State, however scientific data about the efficacy of these products in this region are sparse. The aim of the present study was to evaluate the frequency of R. (B.) microplus populations resistant to amitraz acaricides in the Southern region of Rio Grande do Sul State. So, the efficacies of five commercial products containing amitraz were compared. Results showed that the efficacy of amitraz acaricides was lower than 69% in 23% of studied populations. Nearly 29% of the tick samples showed an acaricide efficacy equal to zero, suggesting the presence of a high level of resistance to amitraz. Moreover, the most used commercial product in the region showed the lowest efficacy index. These results alert about the possible spreading of resistant on tick populations and justify research directed toward the search for alternative products to control this parasite.
authors.affiliation: Faculdade de Veterinária, Universidade Federal de Pelotas-UFPel, CP 354, CEP 96010-900, Pelotas-RS, Brazil. tsantos@ufpel.edu.br
authors.forename: Tânia Regina Bettin
authors.initials: TR
authors.lastname: dos Santos
authors.forename: Felipe Geraldes
authors.initials: FG
authors.lastname: Pappen
authors.forename: Nara Amélia
authors.initials: NA
authors.lastname: da Rosa Farias
authors.forename: Itabajara
authors.initials: I
authors.lastname: da Silva Vaz Junior
mesh_terms: D000818:Animals; D001938:Brazil; D007306:Insecticides; D048494:Rhipicephalus; D014052:Toluidines
chemical_list: D007306:Insecticides; D014052:Toluidines; C014983:amitraz