Acaricides efficiency on Rhipicephalus (Boophilus) microplus from Bahia state North-Central region Eficiência de acaricidas sobreRhipicephalus (Boophilus) microplusna região Centro-Norte, Bahia

The cattle tick Rhipicephalus (Boophilus) microplus is responsible for major losses in the Brazilian livestock, mainly due to reduction in cattle productive performance. Resistance development to major classes of acaricide widely used nowadays has been extensively reported, as well as the occurrence of residues from these compounds in animal products and the environment. This study aimed to evaluate the efficiency of acaricides on R. (B.) microplus collected from rural properties in the North-Central region of Bahia State. Ticks were collected in several cattle farms in the cited region, and an in vitro acaricide efficiency assay was performed based on the immersion of ticks in acaricide solutions made according to manufacturers' recommendations. The results obtained in the experiments indicated varying degrees of efficiency of the several bases studied, with the products benzofenilurea, macrocyclic lactone and fipronil showing the highest levels of efficiency, 100%, 100% and 97.34%, respectively. It was possible to conclude that, for the region studied, there are different degrees of commercial acaricides efficiency, and many present less than 95% effectiveness, value determined as acceptable by the Brazilian legislation.<br>O carrapato Rhipicephalus (Boophilus) microplus &#233; respons&#225;vel por grandes perdas na pecu&#225;ria brasileira, principalmente devido &#224; redu&#231;&#227;o no desempenho produtivo dos animais. A resist&#234;ncia do parasita a diferentes classes de acaricidas tem sido amplamente relatada, bem como os problemas de ocorr&#234;ncia de res&#237;duos desses compostos em produtos de origem animal e no ambiente. Esse estudo teve como objetivo avaliar a efici&#234;ncia de diversos acaricidas sobre popula&#231;&#245;es de R. (B.) microplus provenientes de propriedades rurais da Regi&#227;o Centro-Norte do Estado da Bahia, Brasil. Tele&#243;ginas ingurgitadas foram colhidas em diferentes propriedades da regi&#227;o e submetidas a ensaio in vitro de efici&#234;ncia de acaricidas, baseado na imers&#227;o dos carrapatos em solu&#231;&#245;es de acaricidas feitas seguindo as recomenda&#231;&#245;es dos fabricantes. Os resultados obtidos indicam n&#237;veis variados de efici&#234;ncia das bases estudadas, com os acaricidas benzofenilureia, lactona macroc&#237;clica e fipronil apresentando os &#237;ndices mais altos de efici&#234;ncia, 100%, 100% e 97.34%, respectivamente. Pode-se concluir que, para a regi&#227;o estudada, os acaricidas apresentam n&#237;veis diversos de efici&#234;ncia, e muitos deles possuem efic&#225;cia de menos de 95%, como recomendado pela legisla&#231;&#227;o brasileira.