Use of microdam reservoirs as larval habitat by malaria vectors

Microdams are important for water management in rural areas of Africa. Microdams retain water used by people for domestic and agricultural use, but the potential for malaria vector larvae to use aquatic habitats associated with microdams is poorly understood. The perimeters of microdam reservoirs in western Kenya were sampled for Anopheles larvae in the dry and rainy seasons. In the dry season, malaria vector species and non-vector species were found in microdam-associated habitats. The primary malaria vector Anopheles funestus was more common in vegetated habitats relative to open water and hoof print aggregations. In the rainy season, Anopheles gambiae s.l., another primary malaria vector, dominated Anopheles communities in microdam reservoirs. Anopheles gambiae s.l. larvae were more common in hoof print aggregations relative to other habitat types along the microdam reservoir perimeters. Microdams may provide a dry season refuge habitat for malaria vectors, contributing to population persistence through the dry season. Microdams also appear to provide important habitat for An. gambiae s.l. larvae in the rainy season. This suggests a potential conflict between public health concerns about malaria and people’s need for stable and reliable sources of water. To alleviate this conflict, variation in habitat suitability within and among microdams could potentially be exploited to reduce conditions favorable to malaria vector larvae.