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dc.contributor.authorAbebe, Aklilu Seyoum
dc.date.accessioned2012-01-12T11:30:16Z
dc.date.available2012-01-12T11:30:16Z
dc.date.issued2012-01-12
dc.identifier.urihttp://ir-library.ku.ac.ke/handle/123456789/2376
dc.descriptionThe RA 640.A2en_US
dc.description.abstractMalaria is one of the major public health problems in tropical Africa. The existing vector control tolls are not sufficient to reduce the already escalating burden of the disease. The main aims of this study were to search for simple and cost-effective plant-based repellents against the main malaria vectors in Africa, and compare existing and alternative methods of utilizing the plants. The repellency of the following plants suggested by the ethnobotanical survey and the literature was evaluated against Anopheles gambiae sensu stricto Giles in experimental huts within a screen-walled greenhouse: Ocimum americanum Linnaeus, Ocimum kilimandscharicum Guerke, Ocimum suave Willd., Lantana camara L, Azadirachta indica Adrien Jussieu, Hyptis suaveolens Poit, Lippia ukambensis Spreng and Corymbia citriodora Hook. Thermal expulsion, direct burning, and intact potted plants were tested as alternative application methods. When thermally expelled (from modified traditional stoves), only H. suaveolens failed to repel mosquitoes, whereas the leaves of C. citriodora (74.5% repellency, p<0.0001), leaves and seeds of O. suave (53.1% repellency, P<0.0001) and O. kilimandscharicum (52.0% repellency, P<0.0001) were the most effective. Leaves of C. citriodora also exhibited the highest repellency (51.3% repellency, P< 0.0001) by direct burning. Intact potted plants of O. americanum, L. camara, and L. ukambensis repelled on average 39.7, 32.4 and 33.3% (P<0.0001) of the mosquitoes respectively in semi-field experimental system. The effectiveness of live potted plants and thermal expulsion in repelling An. gambiae s.l. and An funestus was also estimated in traditional houses in western Kenya. Ocimum americanum, L. camara and L. ukambensis were tested in potted form, and C. citriodora, O. kilimandscharicum and O. suave by thermal expulsion. All plant species showed significant repellency against An. gambiae s.l., with the highest repellency by C. citriodora (48.71% P<0.0001) followed by an equal level of repellency of O. kilimandscharicum and O. suave (44.54%, P=0.001) during application of plants by thermal expulsion. All the three also showed residual effects against An. gambiae s.l. Similarly, potted plants of O. americanum and L. camara repelled An. gambiae s.l. significantly (37.91%, P=0.004 and 27.22%, P=0.05 respectively). Thermal expulsion of O. kilimandscharicum significantly repelled An. funestus Giles, although none of the potted plants repelled this species. Volatile oils extracted by steam distillation of plants (O. americanum, O. kilimandscharicum, O. suave H. suaveolens and L. camara) were also evaluated against An. gambiae s.s. The essential oils from all candidate plants showed complete protection for less than an hour, but this was 4 hours for the standard DEET. Gas chromatographic analysis of the volatiles emitted by thermally expelled C. citriodora revealed that the major constituents are citronellal, citronelol and iso- pulegol, and that of O. kilimandscharicum and O. suave are camphor and trans- methyl iso-eugenol, respectively. The major constituent from potted plants of O. americanum is a-terpineole. This study showed that modifications of traditional practices represented by thermal expulsion and intact potted plants can reduce domestic exposure to malaria vectors. As such, they may represent a sustainable and readily applicable malaria vector control tool for incorporation into integrated vector management programsen_US
dc.description.sponsorshipKenyatta Universityen_US
dc.language.isoenen_US
dc.subjectMosquitoes--Control--Africa,Eastern//insecticidal plants//Repllentsen_US
dc.titleStudies on the use of repellent plants and plant products aganist the main Malaria vectors in Eastern Africaen_US
dc.typeThesisen_US


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