title: First report of fipronil resistance in Rhipicephalus (Boophilus) microplus of Mexico.
abstract: Five strains of Rhipicephalus (Boophilus) microplus collected from Tamaulipas Mexico were tested for resistance against several classes of acaricides commonly used. All were resistant to fipronil. Four of five were co-resistant to permethrin and coumaphos in addition to being resistant to fipronil. One strain, El Zamora was found multi-resistant to permethrin, coumaphos, fipronil, and amitraz. Selection with fipronil for 3 generations produced a resistance ratio of 8.3 and 9.4 at the LC(50) and the LC(99) estimates, respectively. Permethrin resistance in El Zamora was possibly linked to elevated esterase (CZEST9) and could be a contributing factor of resistance to fipronil. The implications of resistance for the control of the southern cattle tick in the future are discussed.
authors.affiliation: USDA, ARS Cattle Fever Tick Research Laboratory, 22675 N. Moorefield Rd., Edinburg, TX 78541, USA. robert.miller@ars.usda.gov
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Miller
authors.forename: Consuelo
authors.initials: C
authors.lastname: Almazán
authors.forename: Martín
authors.initials: M
authors.lastname: Ortíz-Estrada
authors.forename: Ronald B
authors.initials: RB
authors.lastname: Davey
authors.forename: John E
authors.initials: JE
authors.lastname: George
authors.forename: Adalberto Peréz
authors.initials: AP
authors.lastname: De León
mesh_terms: D056810:Acaricides; D000818:Animals; D003372:Coumaphos; D004351:Drug Resistance; D004950:Esterases / Q000235:genetics; D008800:Mexico; D009154:Mutation; D026023:Permethrin; D011720:Pyrazoles; D048494:Rhipicephalus / Q000235:genetics; D015222:Sodium Channels / Q000235:genetics; D014052:Toluidines
chemical_list: D056810:Acaricides; D011720:Pyrazoles; D015222:Sodium Channels; D014052:Toluidines; C014983:amitraz; D026023:Permethrin; D004950:Esterases; D003372:Coumaphos; C082360:fipronil