In Vitro Effect of Volatile Substances from Eucalyptus Oils on Rhipicephalus Microplus

Volatile oils have been extensively investigated as an alternative for tick control. This study evaluated the in vitro effects of volatile compounds emanated by Corymbia citriodora (Hook.) K.D.Hill & L.A.S.Johnson and Eucalyptus globulus Labill., Myrtaceae, volatile oils and their major compounds, citronellal and 1,8-cineole, respectively, at doses of 10, 20, 40, 60, 80 and 100 mg/g, on Rhipicephalus microplus larvae and engorged females. The effects of these volatile oils were compared with those of commercial acaricides. In bioassays with engorged females, percentages of oviposition inhibition (OI %) and efficacy of the product (EP %) were determined, as well as tick larval mortality. The larval tests with citronellal presented high mortalities (> 80%) for all analysed doses, except 10 mg/g, while those for 1,8-cineole at the lowest dose (10 and 20 mg/g) produced the highest mortality (> 85%). In general, the volatile compounds released by these oils resulted in larval mortality and inhibition of the reproductive parameters in the engorged females, with efficacies over 80%.