Evaluation of the efficacy of cypermethrin and amitraz against Rhipicephalus (Boophilus) microplus, in the State of Pernambuco, Brazil

ABSTRACT: The Rhipicephalus (Boophilus )microplus is an important tick species which affect bovines in tropical areas. Its control is based on the use of chemical acaricides, but the frequent use of these substances has been conducted to the development of tick resistance. The aim of this study was to assess the efficacy of cypermethrin and amitraz against R. (B. )microplus collected of bovines from different municipalities of the state of Pernambuco. From August 2009 to July 2011, engorged females were collected and subjected to the "Adult Immersion Test" in order to evaluate the efficacy of cypermethrin and amitraz. The results indicate that populations of R. (B. )microplus from Pernambuco present resistance to acaricides (i.e., cypermethrin and amitraz). In this study, a single population (Brejo da Madre de Deus) was susceptible to cypermethrin, whereas two (Timbaúba and Limoeiro) were susceptible to amitraz. Data herein reported follow a pattern observed in other regions of Brazil and alert to the fact that alternative measures of control should be implemented in this area studied.