Ação larvicida de derivados arilsulfonílicos da (+)- cânfora e da (+)- isopinocanfona sobre o carrapato Boophilus microplus

Chemical Composition and Acaricidal Activity of Essential Oil of Lavandula dentata L. on Engorged Females of Rhipicephalus (Boophilus) microplus (Acari: Ixodidae)

PURPOSE

Rhipicephalus (Boophilus) microplus is one the most significant ectoparasite in cattle farming in tropical and subtropical regions, causing problems to livestock health worldwide. The control of this ectoparasite primarily relies on the use of synthetic acaricides. However, the emergence of acaricide resistance has stimulated the search for new control alternatives, including phytocompounds with acaricidal and insecticidal potential. The aim of this study was to evaluate the acaricidal potential of Lavandula dentata essential oil against the engorged females of R. (B.) microplus.

METHODS

Engorged females were obtained from infested bovines in dairy farms in Pernambuco, Brazil. L. dentata essential oil was extracted, and adult immersion test assays were performed using the following oil concentrations: 0.2%, 0.4%, 0.6%, 0.8%, and 1%.

RESULTS

L. dentata essential oil at a concentration of 1% was lethal to all engorged females, and concentrations of 0.6% and 0.8% caused mortality of 98.6% and 99.1%, respectively. These concentrations disrupted the reproductive capacity of engorged females, reducing oviposition by more than 90% and preventing egg hatching by over 87%.

CONCLUSION

The data revealed that L. dentata essential oil possesses effective pharmacological properties against R. (B.) microplus and could be used for tick control following in vivo evaluation, thus contributing to mitigating the negative impacts of synthetic acaricide use.

In vitro activity of the hydroalcoholic extract of Chenopodium ambrosioides against engorged females of Rhipicephalus (Boophilus) microplus

ABSTRACT: Rhipicephalus (Boophilus) microplus, known as the cattle tick, is a cause of great economic losses for dairy cattle farming because of its high frequency of occurrence and the difficulty in controlling it. The aim of this study was to evaluate the in vitro activity of Chenopodium ambrosioides extract on R. (B.) microplus. For this purpose, 125 females were selected and classified into five groups according to their weight, in order to ensure that the females used presented homogeneous weight. The treatments comprised 40 and 60% extracts of Chenopodium ambrosioides, distilled water, ethanol (70ºGL) and 12.5% amitraz. The extracts of C. ambrosioides (40 and 60%) showed effectiveness of 99.7 and 100% and higher percentages of dead females than the other treatments: 64 and 96%, respectively (p<0.001). In the groups exposed to distilled water and ethanol (70º GL), 92 and 88% of the females maintained oviposition. In the females exposed to 40 and 60% extracts, oviposition of 36 and 4% occurred, respectively. It was concluded that the extract of Chenopodium ambrosioides, at both concentration evaluated, had high efficiency against engorged females of cattle ticks.

Efeito do extrato aquoso e etanólico do angico preto sobre larvas de Rhipicephalus (Boophilus) microplus

Rhipicephalus (Boophilus) microplus representa um grande problema na bovinocultura e o uso de acaricidas é a medida de controle profilático e terapêutico mais comum contra esses ectoparasitos. Os principais problemas relacionados com essa prática dizem respeito ao desenvolvimento de linhagens resistentes de carrapatos. Assim, objetivou-se determinar o efeito de extratos da casca de Anadenanthera macrocarpa sobre as larvas de R. (B.) microplus, obtidas de um pool de ovos, acondicionadas em tubo de polietileno. De acordo com os resultados, o extrato aquoso na concentração de 8,26mg.mL-1 causou 85% de mortalidade nas primeiras 12 horas. Quanto ao extrato etanólico, observou-se maior mortalidade nas concentrações 12,5; 6,25 e 1,56mg.mL-1, em torno de 84%, percentuais semelhantes ao amitraz. Os controles negativos não apresentaram mortalidade durante o experimento. Assim, tanto o extrato aquoso como o extrato etanólico apresentaram efeito larvicida, embora o extrato etanólico tenha sido mais eficiente para a espécie, podendo ser uma alternativa no controle desse ectoparasito.

Acaricidal activity of Palicourea marcgravii, a species from the Amazon forest, on cattle tick Rhipicephalus (Boophilus) microplus

Leaves of Palicourea marcgravii were extracted successively with hexane, ethyl acetate and ethanol in order to evaluate their acaricidal activity on larvae and adult stages of the cattle tick Rhipicephalus (Boophilus) microplus. The ethyl acetate extract showed the highest bioactivity of the tested extracts, which contained 0.12% monofluoroacetic acid. On engorged female, the ethyl acetate extract showed a lethal concentration 50% - LC(50)=30.08 mg ml(-1), inhibitory concentration 50% - IC(50)=5.79 mg ml(-1) and lethal time 50% - LT(50)=4.72 days; 100% reproduction was controlled at concentrations of 50 mg ml(-1) and on larvae the ethyl acetate extract showed a LC(50)=2.46 mg ml(-1). No alkaloids were detected in any of the extracts. This is the first report on the acaricidal activity of P. marcgravii extracts against R. microplus as well as the acaricidal properties of a plant species containing monofluoroacetic acid.