Caracterização molecular da resistência de populações do carrapato dos bovinos do estado de Minas Gerais às principais bases químicas carrapaticidas

Abstract

The monitoring of the resistance of cattle tick populations in Brazil to the chemical bases in use is largely limited to investigation of the phenotypic profile. There are few studies investigating the role played by the genotypic profile in acaricide resistance in the country. Therefore, the aim of the present study was to carry out molecular characterization and trace out the genetic profile of populations of Rhipicephalus microplus with respect to resistance to the organophosphate and pyrethroid chemical groups. For that purpose, were genotyped larvae belonging to 893 populations (587 for pyrethroids and 306 for organophosphates), using the polymerase chain reaction technique. It was found that 75.49% and 97.44% of the samples studied showed resistance to the organophosphates and pyrethroids, respectively. Among the populations resistant to pyrethroids, 91.9% were heterozygotes, showing that most of the resistant populations have only one allele responsible for resistance. Therefore, it is possible to conclude that the genotyped populations have high resistance to organophosphates, and even more so to pyrethroids. This information are fundamental to understanding the mechanisms of resistance of R. microplus to acaricides, which can help to improve control techniques.