RESUMO
With the objective of evaluating Rhipicephalus (Boophilus) microplus resistance to cipermetrina and amitraz, were collected engorged tick females from cattle on 20 farms on the Santa Catarina Plateau, in southern Brazil, between January of 2004 and May of 2006. Were also received 20 groups of engorged R. (B.) microplus females, collected by cattle farmers requesting acaricidal efficacy (AE) testing. Were performed in vitro tests, which consisted of immersing engorged females in cypermethrin (0.015%) and in amitraz (0.025%). An AE >95% was considered indicative of effectiveness. Of the 20 collected groups, 18 (90%) showed cypermethrin resistance and 1 (5%) showed amitraz resistance. Of the 20 received groups, 19 (95%) showed cypermethrin resistance and 2 (10%) showed amitraz resistance. The AE of cypermethrin was found to be >95%, 85-94%, and 55-64%, respectively, in 4 (57.1%), 2 (28.6%), and 1 (14.3%) of 7 reference groups, collected in the 1997-2001 period. The AE of amitraz was >95% in all of those groups. Among the groups of specimens received for analysis in that period, the AE of amitraz was >95% in 6 (85.71%) and 75-84% in 1 (14.28%). R. (B.) microplus resistance to acaricides is increasing on the Santa Catarina Plateau.
Assuntos
Inseticidas/farmacologia , Piretrinas/farmacologia , Rhipicephalus/efeitos dos fármacos , Toluidinas/farmacologia , Animais , Brasil , Bovinos/parasitologia , Feminino , Resistência a InseticidasRESUMO
With the objective of evaluating Rhipicephalus (Boophilus) microplus resistance to cipermetrina and amitraz, were collected engorged tick females from cattle on 20 farms on the Santa Catarina Plateau, in southern Brazil, between January of 2004 and May of 2006. Were also received 20 groups of engorged R. (B.) microplus females, collected by cattle farmers requesting acaricidal efficacy (AE) testing. Were performed in vitro tests, which consisted of immersing engorged females in cypermethrin (0.015%) and in amitraz (0.025%). An AE >95% was considered indicative of effectiveness. Of the 20 collected groups, 18 (90%) showed cypermethrin resistance and 1 (5%) showed amitraz resistance. Of the 20 received groups, 19 (95%) showed cypermethrin resistance and 2 (10%) showed amitraz resistance. The AE of cypermethrin was found to be >95%, 85-94%, and 55-64%, respectively, in 4 (57.1%), 2 (28.6%), and 1 (14.3%) of 7 reference groups, collected in the 1997-2001 period. The AE of amitraz was >95% in all of those groups. Among the groups of specimens received for analysis in that period, the AE of amitraz was >95% in 6 (85.71%) and 75-84% in 1 (14.28%). R. (B.) microplus resistance to acaricides is increasing on the Santa Catarina Plateau.
Com os objetivos de avaliar a resistência do Rhipicephalus (Boophilus) microplus à cipermetrina e ao amitraz no Planalto Catarinense, no período de janeiro de 2004 a maio de 2006, foram coletadas teleóginas em bovinos de 20 propriedades onde os produtores autorizaram a coleta (amostras por conveniência) e recebidas teleóginas de mais 20 propriedades com objetivo de diagnóstico de eficácia. Os testes in vitro foram realizados por imersão de teleóginas em cipermetrina (0,015%) e amitraz (0,025%). Considerando a eficácia igual ou superior a 95%, das 20 propriedades amostradas, 18 (90%) apresentaram resistência à cipermetrina e uma (5%) ao amitraz. Das 20 propriedades com teleóginas para diagnóstico, 19 (95%) apresentaram resistência à cipermetrina e duas (10%) ao amitraz. No período de agosto de 1997 a dezembro de 2001, das sete amostras coletadas, em quatro (57,1%) a eficácia da cipermetrina foi >95%, em duas (28,6%) entre 85% e 94% e em uma, (14,3%) entre 55% e 64%. A eficácia do amitraz foi >95%, em teleóginas de todas as propriedades. Nas amostras para diagnóstico, seis (85,71%) apresentaram eficácia para o amitraz >95% e uma (14,28%) entre 75% e 84%. A resistência desse ixodídeo aos carrapaticidas testados é crescente no Planalto Catarinense.
