title: Resistance to cypermethrin, deltamethrin and chlorpyriphos in populations of Rhipicephalus (Boophilus) microplus (Acari: Ixodidae) from small farms of the State of São Paulo, Brazil.
abstract: A field survey of resistance was conducted based on the larval packet test technique with synthetic pyrethroids (cypermethrin and deltamethrin) and organophosphates (chlorpyriphos) in Rhipicephalus (Boophilus) microplus field populations from six different regions of the State of São Paulo (Brazil). 82.6% of the populations showed resistance to cypermethrin, 86.36% to deltamethrin and 65.25% to chlorpyriphos, with 50% presenting resistance to both SP and OP acaricide. According to the questionnaires completed by the producers, OP+SP mixtures followed by SP-only formulations were the products most commonly used for controlling the cattle tick in the surveyed areas. The present study showed high occurrence of resistance to SP and OP in the State of São Paulo, Brazil and revealed the type of strategy adopted by small dairy farms in this state. This information is fundamental in order to establish the monitoring of resistance on each farm individually, contributing to the rational use of acaricides for the control of R. (B.) microplus.
authors.affiliation: Centro de Pesquisa e Desenvolvimento em Sanidade Animal, Instituto Biológico, Avenida Conselheiro Rodrigues Alves, 1252, CEP: 0414-002, São Paulo, SP, Brazil. mendes@biologico.sp.gov.br
authors.forename: M C
authors.initials: MC
authors.lastname: Mendes
authors.forename: C K P
authors.initials: CK
authors.lastname: Lima
authors.forename: A H C
authors.initials: AH
authors.lastname: Nogueira
authors.forename: E
authors.initials: E
authors.lastname: Yoshihara
authors.forename: D P
authors.initials: DP
authors.lastname: Chiebao
authors.forename: F H L
authors.initials: FH
authors.lastname: Gabriel
authors.forename: T E H
authors.initials: TE
authors.lastname: Ueno
authors.forename: A
authors.initials: A
authors.lastname: Namindome
authors.forename: G M
authors.initials: GM
authors.lastname: Klafke
mesh_terms: D000818:Animals; D002417:Cattle; D002418:Cattle Diseases / Q000469:parasitology* / Q000517:prevention & control; D004390:Chlorpyrifos; D005260:Female; D007305:Insecticide Resistance; D007306:Insecticides; D008297:Male; D009570:Nitriles; D011722:Pyrethrins; D048494:Rhipicephalus / Q000254:growth & development*; D011795:Surveys and Questionnaires; D013984:Tick Infestations / Q000517:prevention & control / Q000662:veterinary*
chemical_list: D007306:Insecticides; D009570:Nitriles; D011722:Pyrethrins; C017160:cypermethrin; C017180:decamethrin; D004390:Chlorpyrifos