title: Repellent and mosquitocidal effects of leaf extracts of Clausena anisata against the Aedes aegypti mosquito (Diptera: Culicidae).
abstract: Mosquitoes are rapidly developing resistance to insecticides that millions of people relied on to protect themselves from the diseases they carry, thereby creating a need to develop new insecticides. Clausena anisata is used traditionally as an insect repellent by various communities in Africa and Asia. For this study, the repellency and adulticidal activities of leaf extracts and compounds isolated from this plant species were evaluated against the yellow fever mosquito, Aedes aegypti. In the topical application assays, using total bites as an indicator, repellency was dose dependent, with the acetone crude extract (15 %) having 93 % repellence and the hexane fraction (7.5 %) 67 % repellence after 3 h. Fractionation resulted in a loss of total repellence. As mosquito-net treating agents, the acetone and hexane extracts of C. anisata, both at 15 %, had average repellences of 46.89 ± 2.95 and 50.13 ± 2.02 %, respectively, 3 h after exposure. The C. anisata acetone extract and its hexane fraction caused mosquito knockdown and eventually death when nebulised into the testing chamber, with an EC50 of 78.9 mg/ml (7.89 %) and 71.6 mg/ml (7.16 %) in the first 15 min after spraying. C. anisata leaf extracts have potential to be included in protection products against mosquitoes due to the repellent and cidal compounds contained therein.
authors.affiliation: Department of Paraclinical Sciences, Faculty of Veterinary Science, University of Pretoria, P. Bag X04 Onderstepoort, Pretoria, 0110, South Africa. Lilian.Mukandiwa@up.ac.za.
authors.forename: Lillian
authors.initials: L
authors.lastname: Mukandiwa
authors.affiliation: Department of Paraclinical Sciences, Faculty of Veterinary Science, University of Pretoria, P. Bag X04 Onderstepoort, Pretoria, 0110, South Africa.
authors.forename: Jacobus Nicolaas
authors.initials: JN
authors.lastname: Eloff
authors.affiliation: Biomedical Research Centre, Faculty of Veterinary Science, University of Pretoria, Onderstepoort, Pretoria, 0110, South Africa.
authors.forename: Vinny
authors.initials: V
authors.lastname: Naidoo
mesh_terms: D000330:Aedes / Q000187:drug effects*; D000818:Animals; D054700:Clausena / Q000737:chemistry*; D006168:Guinea Pigs; D007299:Insect Bites and Stings / Q000517:prevention & control*; D007302:Insect Repellents / Q000302:isolation & purification / Q000494:pharmacology*; D010936:Plant Extracts / Q000302:isolation & purification / Q000494:pharmacology*; D018515:Plant Leaves / Q000737:chemistry; D013019:South Africa
chemical_list: D007302:Insect Repellents; D010936:Plant Extracts
keywords: Botanical repellents; Vector control; Yellow fever mosquito