title: Repellent, irritant and toxic effects of 20 plant extracts on adults of the malaria vector Anopheles gambiae mosquito.
abstract: Pyrethroid insecticides induce an excito-repellent effect that reduces contact between humans and mosquitoes. Insecticide use is expected to lower the risk of pathogen transmission, particularly when impregnated on long-lasting treated bednets. When applied at low doses, pyrethroids have a toxic effect, however the development of pyrethroid resistance in several mosquito species may jeopardize these beneficial effects. The need to find additional compounds, either to kill disease-carrying mosquitoes or to prevent mosquito contact with humans, therefore arises. In laboratory conditions, the effects (i.e., repellent, irritant and toxic) of 20 plant extracts, mainly essential oils, were assessed on adults of Anopheles gambiae, a primary vector of malaria. Their effects were compared to those of DEET and permethrin, used as positive controls. Most plant extracts had irritant, repellent and/or toxic effects on An. gambiae adults. The most promising extracts, i.e. those combining the three types of effects, were from Cymbopogon winterianus, Cinnamomum zeylanicum and Thymus vulgaris. The irritant, repellent and toxic effects occurred apparently independently of each other, and the behavioural response of adult An. gambiae was significantly influenced by the concentration of the plant extracts. Mechanisms underlying repellency might, therefore, differ from those underlying irritancy and toxicity. The utility of the efficient plant extracts for vector control as an alternative to pyrethroids may thus be envisaged.
authors.affiliation: UR Hortsys, Cirad, Montpellier, France.
authors.forename: Emilie
authors.initials: E
authors.lastname: Deletre
authors.affiliation: UR Hortsys, Cirad, Montpellier, France ; Plant Health Department, ICIPE, Nairobi, Kenya.
authors.forename: Thibaud
authors.initials: T
authors.lastname: Martin
authors.affiliation: Plant Health Department, ICIPE, Nairobi, Kenya.
authors.forename: Pascal
authors.initials: P
authors.lastname: Campagne
authors.affiliation: UMR CBGP, INRA-CIRAD-IRD-Montpellier SupAgro, Montpellier, France.
authors.forename: Denis
authors.initials: D
authors.lastname: Bourguet
authors.affiliation: UR Hortsys, Cirad, Montpellier, France.
authors.forename: Andy
authors.initials: A
authors.lastname: Cadin
authors.affiliation: Institut des Biomolécules Max Mousseron, Faculté de Pharmacie, Montpellier, France.
authors.forename: Chantal
authors.initials: C
authors.lastname: Menut
authors.affiliation: Montpellier SupAgro, USAE, Montpellier, France.
authors.forename: Romain
authors.initials: R
authors.lastname: Bonafos
authors.affiliation: UMR MiVEGEC, IRD-CNRS-UM1-UM2, Montpellier, France.
authors.forename: Fabrice
authors.initials: F
authors.lastname: Chandre
mesh_terms: D000375:Aging / Q000187:drug effects; D000818:Animals; D000852:Anopheles / Q000187:drug effects* / Q000254:growth & development*; D005247:Feeding Behavior / Q000187:drug effects; D005260:Female; D007302:Insect Repellents / Q000633:toxicity*; D007303:Insect Vectors / Q000187:drug effects* / Q000254:growth & development; D007509:Irritants / Q000633:toxicity*; D008288:Malaria / Q000469:parasitology; D010936:Plant Extracts / Q000633:toxicity*; D018675:Toxicity Tests
chemical_list: D007302:Insect Repellents; D007509:Irritants; D010936:Plant Extracts