Malaria is one of the deadliest vector-borne diseases known. Controlling malaria requires an understanding of the ecology of local malaria vectors. The potential for microdams to provide larval habitats for malaria vectors is poorly understood, despite the importance of microdams for water management in rural areas of Africa. The perimeters of microdam reservoirs in western Kenya were sampled for Anopheles larvae in the dry and rainy seasons. In the dry season, both malaria vector and non-vector species were found in microdam-associated habitats, suggesting that microdams may contribute to population persistence through the dry season. In the rainy season, microdams may provide important habitat for Anopheles gambiae s.l., as this species dominated Anopheles communities in microdams. Thus, microdams may represent a conflict between public health concerns about malaria and people's need for stable and reliable water sources.Anopheles gambiae s.l. larvae also use a range of smaller, temporary bodies of stagnant water as habitat. Predictive models of the locations of these habitats may provide a basis for understanding the spatial determinants of malaria transmission. Four landscape variables and accumulated precipitation were used to model larval habitat locations through two methods: logistic regression and random forest. The random forest models were more accurate than the logistic regression models, especially when accumulated precipitation was included to account for seasonal differences in precipitation. Larval habitats were more likely to be present in locations with a lower slope to contributing area ratio, closer to streams, and in agricultural land use. Differences among soil types were also found, and the probability of larval habitat presence increased with increasing accumulated precipitation. This model was used to assess the contribution of larval habitat proximity to houses to the number of adult malaria vectors in those houses. Houses were sampled for adult Anopheles females, and variation in household-level insecticide-treated net (ITN) use was assessed. The number of adult female An. gambiae s.l. per house increased with increasing mean probability of larval habitat presence within 500 m, which was a better predictor than distance to the nearest larval habitat. Thus, the configuration of larval habitats within a given landscape may affect the relationship between larval habitat location and adult malaria vector spatial distribution. Also, houses in which all residents slept under ITNs the previous night had fewer adult female An. gambiae s.l. than other houses. There was no difference in the number of An. gambiae s.l. females collected in houses without ITNs and houses where only some of the residents slept under ITNs, highlighting an important difference between the effects of ITN ownership at the household-level and individual ITN use.Finally, the reemergence of Anopheles funestus in an area of long-term ITN use is described here. ITN use in Asembo, a community in western Kenya, has been high since 1998. The abundance of An. funestus in Asembo was relatively low from 1998-2008. However, the majority of the Anopheles collected here in 2010 and 2011 were An. funestus. This has important implications for malaria transmission in the region, given the current reliance on ITNs as a long-term, stand-alone method of vector control.
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