title: Larvicidal activity of selected aloe species against Aedes aegypti (Diptera: Culiciade).
abstract: Management of mosquito vectors by current classes of mosquitocides is relatively ineffective and necessitates prospecting for novel insecticides with different modes of action. Larvicidal activities of 15 crude extracts from three geographically isolated Aloe ngongensis (Christian), Aloe turkanensis (Christian), and Aloe fibrosa (Lavranos & L.E.Newton) (Xanthorrhoeaceae) species (five each) were evaluated against Aedes aegypti (Linnaeus in Hasselquist) (Diptera: Culiciade L.) yellow fever mosquito. Freshly collected leaves were separately shade-dried to constant weight at room temperature (25 ± 2°C) and powdered. Each powder was macerated in solvents of increasing polarity (hexane, chloroform, ethyl acetate, acetone, and methanol) for 72 h and subsequently filtered. Third-instar larvae (n = 25) of the mosquito were exposed to the extracts at different concentrations for 24 h to establish dose response relationships. All the fractions of A. ngongensis were active below 1 mg/ml except A. fibrosa and A. turkanensis. The highest activity (LC50) mg/ml was obtained with extracts of A. fibrosa hexane (0.05 [0.04-0.06]), followed by A. ngongensis hexane (0.11 [0.08-0.15]) and A. turkanensis ethyl acetate (0.11 [0.09-0.12]). The activities are apparently Aloe species specific and extraction solvent dependent. These findings suggest that extracts from selected Aloe species have mosquitocidal principles that can be exploited in development of new insecticides.
authors.affiliation: Department of Biochemistry & Molecular Biology, Egerton University, P.O. Box 536-20115, Egerton, Kenya.
authors.forename: Judith K
authors.initials: JK
authors.lastname: Chore
authors.affiliation: Department of Biochemistry & Molecular Biology, Egerton University, P.O. Box 536-20115, Egerton, Kenya obonyom@gmail.com.
authors.forename: Meshack
authors.initials: M
authors.lastname: Obonyo
authors.affiliation: Department of Biochemistry & Molecular Biology, Egerton University, P.O. Box 536-20115, Egerton, Kenya.
authors.forename: Francis N
authors.initials: FN
authors.lastname: Wachira
authors.affiliation: Molecular Biology and Bioinformatics Unit, International Centre of Insect Physiology and Ecology, icipe, P.O. Box 30772-00100, Nairobi, Kenya.
authors.forename: Paul O
authors.initials: PO
authors.lastname: Mireji
mesh_terms: D000330:Aedes / Q000187:drug effects*; D000504:Aloe / Q000737:chemistry*; D000818:Animals; D007306:Insecticides / Q000302:isolation & purification / Q000494:pharmacology*; D007814:Larva / Q000187:drug effects; D009032:Mosquito Control; D010936:Plant Extracts / Q000302:isolation & purification / Q000494:pharmacology*; D018515:Plant Leaves / Q000737:chemistry
chemical_list: D007306:Insecticides; D010936:Plant Extracts
keywords: Culicidae; Diptera; mosquitocidal; phytochemicals; yellow fever