Acaricidal efficacy of Origanum onites L. essential oil against Rhipicephalus turanicus (Ixodidae)

Essential oils that were extracted by steam distillation from Origanum onites L. from northwest Turkey were analyzed using an Agilent GC-MSD system. Carvacrol was the major component (64.3%) of the oil. Both pure commercial carvacrol and essential oil at concentrations of 1.5%, 3.2%, 6.25%, 12.5%, 25%, 50%, and 100% (v/v) were tested for their effects against engorging Rhipicephalus turanicus, which were collected from cattle breeding in the region. Pure carvacrol killed all the ticks following 6 h of exposure, while 25% and higher concentrations of the oil were completely effective in killing the ticks by the 24th-hour post-treatment (p < 0.05). The concentrations of 6.25% and 12.5% killed all the ticks by day 2. Lethal concentrations for 50% (LC(50)) and 90% (LC(90)) of 2.34% and 7.12%, respectively, were detected 24 h post-treatment. These findings indicate that the essential oil of O. onites L. has potential to be utilized at reasonable concentrations to control tick infestations.