Acaricidal Effect of Essential Oils from Lippia graveolens (Lamiales: Verbenaceae) Rosmarinus officinalis (Lamiales: Lamiaceae) and Allium sativum (Liliales: Liliaceae) Against Rhipicephalus (Boophilus) microplus (Acari: Ixodidae)
ABSTRACT Acaricidal effects of three essential oils extracted from Mexican oregano leaves (Lippia graveolens Kunth) rosemary leaves (Rosmarinus officinalis L. and garlic bulbs (Allium sativum L. on 10 d old Rhipicephalus (Boophilus) microplus (Canestrini) tick larvae were evaluated by using the larval packet test bioassay. Serial dilutions of the three essential oils were tested from a starting concentration of 20 to 1.25% Results showed that both Mexican oregano and garlic essential oils had very similar activity, producing high mortality (90 100% in all tested concentrations on 10 d old R. microplus tick larvae. Rosemary essential oil produced >85% larval mortality at the higher concentrations (10 and 20% but the effect decreased noticeably to 40% at an oil concentration of 5% and mortality was absent at 2.5 and 1.25% of the essential oil concentration. Chemical composition of the essential oils was elucidated by gas chromatographymass spectrometry analyses. Mexican oregano essential oil included thymol (24.59% carvacrol (24.54% p cymene (13.6% and &ggr; terpinene (7.43% as its main compounds, whereas rosemary essential oil was rich in &agr; pinene (31.07% verbenone (15.26% and 1,8 cineol (14.2% and garlic essential oil was rich in diallyl trisulfide (33.57% diallyl disulfide (30.93% and methyl allyl trisulfide (11.28% These results suggest that Mexican oregano and garlic essential oils merit further investigation as components of alternative approaches for R. microplus tick control.
Journal of medical entomology