Repellent, irritant and toxic effects of plant EO compounds on the malaria vector Anopheles gambiae ss Giles
yrethroids resistance has become widespread among malaria vector Anopheles gambiae populations in Africa. Alternative insecticides must be considered to prevent diseases transmission by An. gambiae bites. The long lasted treated bed nets are particularly efficient to prevent blood meals on humans and thus to reduce the risks of transmissions. Previous studies have identified plant essential oils (EO) as a potential alternative to pyrethroids. Four of them showed significant repellent, irritant and/or toxic effects against An. gambiae. The objective of this study was to evaluate the repellent, irritant and toxic actions of the major compounds of these four EO from citronella (Cymbopogon winterianus), cinnamon (Cinnamomum zeylanicum), cumin (Cuminum cyminum) and thyme (Thymus vulgaris), against females An. gambiae. We tested the spatial repellency, the contact irritancy and the toxicity effects of each product with laboratory tests over 180 females, for each action tested. The complete EO, the mixture of the major compounds (>3%) and the two currently used repellent (DEET) and insecticide (Permethrin) were also tested. The most promising compounds were similarly tested with two strains of An. gambiae: resistant to pyrethroids (KdrKis) and resistant to carbamates (AcerKis). At last assays in tunnels to simulate field conditions were made to determine their efficacy when a blood meal was offered. Carvacrol, geraniol, cuminaldehyde and cinnamaldehyde showed the best repellent and irritant effects among all products tested. Cuminaldehyde and cinnamaldehyde revealed to be more efficient against the resistant strains than the susceptible strain of An. gambiae, and with carvacrol, they were particularly efficient to inhibit blood meals in simulated field conditions. The study also showed interested characteristics of plant EO which led to new research directions to use plant EO for biological control. At last this study was the first to test the efficiency of DEET on resistant An. gambiae strains.
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| Format: | thesis biblioteca |
| Language: | eng |
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University of Amsterdam
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| Subjects: | L72 - Organismes nuisibles des animaux, S50 - Santé humaine, Q60 - Traitement des produits agricoles non alimentaires, |
| Online Access: | http://agritrop.cirad.fr/570414/ http://agritrop.cirad.fr/570414/1/document_570414.pdf |
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