Environmental Changes and Microbial Ecology of African Malaria Vectors

Africa has experienced dramatic environmental changes as a consequence of rapid human population increase, economic development activities, and lack of appropriate environmental management. The present project will examine the effect of one important environmental change in tropical Africa - deforestation - on the chemistry and microbial community of aquatic habitats of the African malaria vector, Anopheles gambiae, in relation to larval mosquito development and survivorship. Malaria epidemiology studies conducted by the PIs in western Kenya highlands over the past eight years demonstrated that aquatic habitats located within deforested areas are more permissive to the development and survival of Anopheles gambiae mosquitoes. Deforestation in the Amazon has also been shown to cause alteration of mosquito community structure and dramatic increases in malaria transmission. However, the underlying mechanisms for reduced mosquito survivorship and delayed development in forested habitats are not understood.

This project examines the hypothesis that deforestation causes a major change in the water chemistry and microbial community structure in aquatic habitats, which in turn facilitates the development and increases the survivorship of Anopheles gambiae larvae. Experiments will be conducted in semi-natural and natural aquatic habitats under conditions representative of forested and deforested land-use types. Nutrients (NH4+, NO3-, and phosphates) in the aquatic habitats will be determined using the ultraviolet absorbance spectrophotometer method, and the bacterial and algal community structure (species composition and relative abundance) will be examined, using DNA barcoding (establishment of algal DNA library, cloning and sequencing of the algal clones, and phylogenetic analysis of algal sequences) and quantitative PCR techniques. These nutrients and microbials are critical to the growth of Anopheles gambiae larvae. Results of this study will provide important insights on how deforestation regulates the microbial community and mosquito larval growth.

Project P.I.: 
Guiyun Yan (Public Health) and Jennifer B. H. Martiny (Ecology & Evolutionary Biology)
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