title: Chemical composition and mosquito repellency of essential oil of Conyza newii propagated in different geographical locations of Kenya.
abstract: Previously, essential oil of Conyza newii (Asterale: Asteracea, Oliv. & Hiern) growing in the northern part of West Pokot (35°E, 1°N) of Kenya was shown to be highly repellent [RD50 = 8.9 × 10(-5) mg/cm(2) , 95% confidence interval (CL)] to Anopheles gambiae s.s. Fumigant toxicity of the oil to the mosquito was also demonstrated. The major constituents of the oil were found to be monoterpenoids, including (S)-(-)-perillyl alcohol, (S)-(-)-perillaldehyde, geraniol, (R)-(+)-limonene, trans-β-ocimene and 1,8-cineol. In this study, the chemical composition and repellency of essential oils of the plant seedlings collected from West Pokot (35°E, 1°N) and propagated in seven different geographical regions of Kenya [West Pokot (35°E, 1°N), Kilome (37°E, 1°S), Naivasha (36°E, 0°), Webuye (34°E, 1°N), Nyakach (34°E, 0°), Kericho (35°E, 0°) and Nairobi (36°E, 1°S)] were compared. There were significant variations (P < 0.01, 95% CL) in the relative proportions of the six constituents and this was reflected in the repellency of the essential oils (P < 0.01, 95% CL). Higher repellency of the oil was associated with greater proportions of (S)-(-) perillyl alcohol, (S)-(-)-perillaldehyde and geraniol, and lower repellency was associated with an increased proportion of (R)-(+)-limonene. The results suggest significant epigenetic (chemotypic) variations in the repellency and composition of C. newii essential oils growing in different regions of Kenya.
authors.affiliation: Department of Chemistry, School of Physical Sciences, Makerere University, Kampala, Uganda.
authors.forename: W P
authors.initials: WP
authors.lastname: Mayeku
authors.forename: N I
authors.initials: NI
authors.lastname: Omollo
authors.forename: O J
authors.initials: OJ
authors.lastname: Odalo
authors.forename: A
authors.initials: A
authors.lastname: Hassanali
mesh_terms: D000818:Animals; D000852:Anopheles; D035401:Conyza / Q000737:chemistry*; D004777:Environment; D007302:Insect Repellents / Q000737:chemistry; D007630:Kenya; D009822:Oils, Volatile / Q000737:chemistry
chemical_list: D007302:Insect Repellents; D009822:Oils, Volatile
keywords: Chemotypes; epigenetic variations