Pattern of Host Seeking and Oviposition Preferences of Malaria Vectors in Kilifi County, Coastal Kenya
Hemed, Abdullah S
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Most malaria vectors alternate between their vertebrate hosts and stagnant water bodies for blood meal and oviposition sites respectively. These two resources are obligatory requirements for completion of the mosquito gonotrophic cycle. Knowledge of spatial distribution and factors influencing habitat productivity of Anopheles mosquitoes is mandatory in planning their control. The current study was carried out with the aim of estimating the host seeking and oviposition patterns of malaria vector mosquitoes. Mechanized aspiration for indoor resting mosquito collection and larval habitat characterization was done to evaluate the productivity and fitness of emerging adult mosquitoes at Jaribuni village in Kilifi at the coast of Kenya, from December 2010 to May 2011. Emergence cages measuring 0.5xO.5xO.5 meters . were placed on natural habitats to monitor emerging adults. Similarly, 5 replicates of artificial aquatic habitats were placed between 0-100m at interval of 25m from selected houses to monitor Anopheles oviposition preferences in distance. All larval habitats were monitored longitudinally for mosquito immature stages and physicochemical characteristics. ELISA technique was used to analyze parasite rate and blood meal source from malaria vectors. A total of 454 sampling visits were made in five types of aquatic habitats, in which 71.79% the habitats found with Anopheles larvae. The highest larval productivity was recorded in pools, river and ditches although the river was the most stable habitat throughout the year. During the 6-month (December 20 10- May 2011) sampling period, the highest proportion of mosquitoes collected indoors were anophelines 57% (296/519). An. Junestus was the predominant species comprising of 97.1 % of all Anopheles collected indoors. Compared to the other Anopheles species, An. Junestus had higher indoor densities, a higher human blood index (0.90) and a higher sporozoite rate (5.03%). In conclusion, Anopheline breeding sites were diverse ranging from the river system, stream pools, ditches, trenches and abandoned water storage tanks. Nevertheless, the river was the most preferred breeding site with abandoned water storage tanks being the least preferred. Generally, salinity, dissolved oxygen, conductivity and temperature were found to have significant influence on habitat productivity. Furthermore, adult anophelines preferred to feed close to their breeding sites.