Structural complexity and temporality: Ecological variables influencing the colonization of Anopheles gambiae habitat by aquatic predators
Description
Anopheles gambiae is the principal vector of malaria in Africa. Efforts using aquatic predators to control these mosquitoes as larvae have been hampered by a paucity of research on ground pool trophic dynamics. Loss of structural complexity has been linked to a loss of specialist predators, and an increase in prey survivorship in other ecological systems. There is evidence that structural complexity influences the distribution of mosquito larvae and their predators. Additionally, temporality may diminish the diversity of predators colonizing ground pools, thereby increasing the survivorship of mosquito larvae. Mosquitoes that selectively colonize temporal habitats early in biological succession would be using a novel strategy to escape predation The roles of structural complexity and temporality were investigated in rural ground pools near the Kenyan coast, in brick making pits in the Kenyan highlands, and in laboratory experiments. Habitats in Malindi city were evaluated to describe the temporality and complexity of urban habitats and to associate these ecological variables with predator guild colonization Flood-disturbed ground pools along the Jeribuni River in coastal Kenya revealed a coincidence of vegetation removal and Anopheles larvae appearance. In two coastal villages, all ground pools were temporal, some containing Anopheles larvae. In a highland valley, eight predator taxa were associated with pools undisturbed by brick makers; three were associated with older habitats. In path analysis of laboratory experiments, the magnitude of mortality experienced by backswimmers from loss of structural complexity exceeded that of direct predation pressure. In other experiments, mortality of An. gambiae was found to significantly exceed that of Culex quinquefasciatus in the presence of three different predators. In the port city Malindi, many man-made habitats were found to be temporal and/or structurally simple. Predator colonization of habitats was statistically associated with habitat type. Swimming pools were associated with planned areas of the city while tire track pools were associated with peri-urban areas. Temporality and low structural complexity reduce colonization of aquatic habitats by predators, increasing survivorship of An. gambiae mosquito larvae in Kenya. Further investigations into ground pool ecology will aid in the development of methods that promote predator colonization and mosquito reduction