AVALIAÇÃO IN VITRO DA RESISTÊNCIA DO CARRAPATO Rhipicephalus microplus A DIFERENTES CARRAPATICIDAS

The present study aimed to evaluate the effectiveness of nine commercial acaricidal (CA) from different brands, formulated with different active ingredient, being: amitraz (CA4, CA8, CA9), cypermethrin (CA1, CA2, CA5, CA6), deltamethrin (CA3) and combinations of cypermethrin, chlorpyrifos and citronella (CA7); against the bovine tick, Rhipicephalus microplus. Engorged females (teleogins) were collected from cattle naturally infested by R. microplus in the municipality of Campo Formoso, BA, for creation and maintenance of a colony in the laboratory. Adult immersion test were performed on colony ticks, in which the following parameters were evaluated: oviposition inhibition (%OI), reproductive efficiency index (%REI), reproductive efficiency percentage (%RE), efficacy (%EF). The tested active ingredient showed variations in intensity for the analyzed parameters. Cypermethrin (CA1, CA2), deltamethrin (CA3) and amitraz (CA4), presented the highest percentage of efficiency, presenting varying between 97.6% and 99.9%. In contrast, amitraz (CA9) demonstrated least effect against the ticks tested in this study (43.5%). It was verified the presence of a multiresistant population to different active ingredient and to different commercial brands tested. It was concluded that ticks showed varying levels of susceptibility to the chemical bases of tested commercial acaricidal, which may be related to the quality of each commercial product used.