Mosquitoes Need More Than Hope

Women wait with their children at a hospital in western Kenya

Malaria is one of the major public health issues in western Kenya and 91% of the one to three million deaths due to malaria worldwide occur in sub-Saharan Africa.  Considerable amounts of funding and research effort has gone into malaria interventions ranging from vaccine and transgenic mosquito development to bed net delivery to reduce malaria vector (mosquito) populations.  It is becoming increasingly evident that there may be no “silver bullet” for the eradication of malaria, and, regardless of the success of other measures, sustainable means for malaria control will only be attained in conjunction with sustainable malaria vector control.

Since 1980, a series of major malaria epidemics has occurred in Kenya’s western highlands. The Kenyan highlands are the most productive area in agriculture in the country due to abundant rainfall. On the other hand, human populations in the highlands have also increased rapidly. Such a rapid increase in human population has caused dramatic changes in the environment, and environmental change, together with global climate change, have been implicated as one important mechanism for malaria resurgence in the region. Environmental changes, such as temperature, humidity and habitat availability can significantly affect mosquito abundance, which in turn affect malaria transmission intensity.  Recent studies suggest that land use changes, such as deforestation, strongly enhance the productivity of malaria vectors, and thus malaria transmission. This is because deforestation exposes aquatic habitats to sunlight, resulting in increased water temperatures. Further, exposure to sunlight may induce changes in the microbial communities that mosquito larvae use for nutrition. Currently, there is little known of how microbial communities in aquatic habitats are regulated by exposure to sunlight and organic nutrients, nor of how mosquito larvae respond to microbial community changes in larval habitats.    

 

Surveying larval habitats in the western Kenyan highlands

Understanding the environmental conditions of successful mosquito development is paramount in establishing vector control strategies to reduce malaria transmission. The microbial ecology of larval mosquitoes is poorly understood, but it may play a vital role in mosquito development. In my work, I examine how land use affects the microbial communities in larval habitats and how microbial communities of aquatic habitats regulate larval populations.  Understanding how land use affects microbial communities and mosquito growth will help to develop rational agricultural and environmental policy, and to develop compelling education programs to policymakers and community members to adopt land use strategies that continue economic and agricultural development while keeping malaria vector populations in check.