Repellent Activities of Essential Oils of Some Plants Used Traditionally to Control the Brown Ear Tick,Rhipicephalus appendiculatus

Abstract

Essential oils of eight plants, selected after an ethnobotanical survey conducted in Bukusu community in Bungoma County, western Kenya (Tagetes minuta, Tithonia diversifolia, Juniperus procera, Solanecio mannii, Senna didymobotrya, Lantana camara, Securidaca longepedunculata, andHoslundia opposita), were initially screened (at two doses) for their repellence against brown ear tick,Rhipicephalus appendiculatus, using a dual-choice climbing assay. The oils ofT. minutaandT. diversifoliawere then selected for more detailed study. Dose-response evaluations of these oils showed thatT. minutaoil was more repellent (RD50= 0.0021 mg) than that ofT. diversifolia(RD50= 0.263 mg). Gas chromatography-linked mass spectrometric (GC-MS) analyses showed different compositions of the two oils.T. minutaoil is comprised mainly ofcis-ocimene (43.78%), dihydrotagetone (16.71%), piperitenone (10.15%),trans-tagetone (8.67%), 3,9-epoxy-p-mentha-1,8(10)diene (6.47%),β-ocimene (3.25%), andcis-tagetone (1.95%), whereasT. diversifoliaoil is comprised mainly ofα-pinene (63.64%),β-pinene (15.00%), isocaryophyllene (7.62%), nerolidol (3.70%), 1-tridecanol (1.75%), limonene (1.52%), and sabinene (1.00%). The results provide scientific rationale for traditional use of raw products of these plants in controlling livestock ticks by the Bukusu community and lay down some groundwork for exploiting partially refined products such as essential oils of these plants in protecting cattle against infestations withR. appendiculatus.