Acaricidal activity of Satureja thymbra L. essential oil and its major components, carvacrol and gamma-terpinene against adult Hyalomma marginatum (Acari: Ixodidae)

Abstract

The acaricidal activity of a volatile essential oil hydrodistillate of Satureja thymbra L (Lamiaceae) and its major constituents, carvacrol and gamma-terpinene, were evaluated against field-collected unfed adult Hyalomma marginatum. The distillate was tested against this tick species at 5, 10, 20, and 40 mu L/L while the two major components were each tested at 10 mu L/L. Generally, tick mortality to the S. thymbra distillate increased with concentration and exposure time. Ticks exposed to vapors from cotton wicks containing at least 40 mu L/L resulted in complete (100%) mortality at 3 h. The lower concentrations provided >= 90% mortality at 3 h post treatment with complete mortality at 24 h. Knockdown was observed only in the carvacrol and gamma-terpinene treatments. Ticks exposed to carvacrol-treated wicks produced >93% knockdown at 3 h but at 24 h approximately 57% were dead. The gamma-terpinene treatment produced >= 90% knockdown at 105 min through 3 h but at 24 h only about 87% of the ticks were dead.