The acaricidal and repellent activity of the essential and nano essential oil of Thymus vulgaris against the brown dog tick, Rhipicephalus sanguineus (Acari: Ixodidae)

Abstract Background The brown dog tick is globally distributed and harms the host in terms of blood feeding and pathogen transferring. Chemicals are traditionally used for the control, but herbal plants has been investigated mainly due to their natural components with killing and repellant effects. Previously, the role of thymol has been described for the biocontrol of ticks at different stages. Therefore, was conducted a study to evaluate the effects of a thymol-rich herbal plant, Thymus vulgaris L., and its major constituents on Rhipicephalus sanguineus. Results In this work, we suggested to perform the larval mortality test using 2 ml microtubes instead of previously described pocket and immersion methods. This method seems to be closer to the environmental condition. The results represented a great activity of the nano EO and thymol on live larva. The nano form was highly effective starting from the lowest concentration (0.125%) showing 88.9% mortality. In comparison, the EO revealed similar effects but at higher concentrations. The nano emulsion and thymol showed also a complete repellency effect against larva at the concentrations of 0.5% and 20 mg/ml, respectively. In adult tick bioassays, thymol was the only substance that accompanied with a statistically significant reduction in female oviposition rate (p < 0.05), however at its utmost concentrations. Conclusion According to the results, the nano EO of T. vulgaris is recommended for the biologic control against R. sanguineus larva. In addition, further studies should be done on the nano material to enhance its effect on the adult female tick reproduction.