Field studies were carried out in Lwanda and Kigoche villages of Homa Bay and Kisumu counties of western Kenya, respectively. Lwanda village is located on the southern shore of the Winam Gulf of Lake Victoria (00°28′28″S, 34°17′22″E) at an altitude of 1,169 m above sea level (Verhulst et al., 2011a (link)). Average rainfall and relative humidity are 1,200 mm and 65%, respectively. The mean temperatures vary between 18°C and 34°C. Hoof prints of cattle and night-grazing hippopotami provide excellent mosquito breeding sites in Lwanda. Fishing and livestock keeping are the main occupation of the local inhabitants. Kigoche village lies adjacent to the Ahero rice irrigation scheme (00°08′19″S, 34°55′50″E) at an altitude of 1,160 m above sea level. Kigoche has an average annual rainfall of 1,000–1,800 mm and an average relative humidity of 65%. Mean annual temperatures in the area vary between 17°C and 32°C. Rice cultivation is the main occupation of the inhabitants. Most houses in the two villages are mud-walled with open eaves, have corrugated iron-sheet roofs, have no ceiling, and are either single- or double-roomed. Eaves, about one foot wide, increase ventilation in the houses and form the predominant entry points for mosquitoes (Snow, 1987 (link); Lindsay and Snow, 1988 (link)). Malaria caused by Plasmodium falciparum is endemic in the two villages. The villages experience two rainy seasons: between April–June and September–October. During these periods, mosquito breeding grounds proliferate, and mosquito populations rapidly increase in size. Cattle, goats, chicken, dogs, cats, and a few sheep constitute the domestic animal population, with cattle being most abundant. Maize, millet and sorghum are cultivated at subsistence level in Lwanda, whereas rice is a main cash crop in Kigoche.
In both villages, trapped mosquitoes were morphologically identified using the keys published by Gillies and Coetzee (1987 ), counted, and the data entered in MS Excel spreadsheets. Culicine mosquitoes were identified up to genus level, and anophelines into An. gambiae sensu lato, An. funestus and other anopheline species. Abdominal statuses of female mosquitoes were categorized as unfed, blood-fed, or gravid. Mosquitoes belonging to the An. gambiae complex were identified to species using a ribosomal DNA Polymerase Chain Reaction assay (Scott et al., 1993 ).
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