―SHORT COMMUNICATION― Leaf essential oil composition and tick repellency activity of Commiphora swynnertonii Burtt BAKARI KAONEKA*, MARGARET MOLLEL and FREDRICK LYATUU Tropical Pesticides Research Institute, P.O. Box 3024, Arusha, Tanzania Abstract The essential oil of the leaves of Commiphora swynnertonii Burtt was found to repel adults of Rhipicephalus appendiculatus Newmann at doses of 0.1 and 10% (v/v) in tick climbing repellency bioassays. Ten sesquiterpenoids were identified in the oil by gas chromatography-mass spectrometry (GC-MS). Two of these compounds, α-copaene and isocaryophyllene, exhibited repellency against adults at different doses. A 0.1% (v/v) solution of α-copaene caused 83% repellency and a 1% solution of this compound was found to be as effective as the commercial arthropod repellent N,N-diethyl-toluamide (DEET). Isocaryophyllene was moderately active, exhibiting 55% repellency in a 10% (v/v) solution. These results suggest that the oil may have a potential in tick control and in integrated tick management.   < back .