Larval breeding sites of the mosquito Aedes aegypti in forest and domestic habitats in Africa and the potential association with oviposition evolution

Adaptations to anthropogenic domestic habitats contribute to the success of mosquito Aedes aegypti as a major global vector of several arboviral diseases. The species inhabited African forests before expanding into domestic habitats and spreading to the rest of the world. Despite a well-studied evolutionary history, how this species initially moved into human settlements in Africa remains unclear. During this initial habitat transition, Ae. aegypti switched from using natural containers like tree holes as larval breeding sites to using artificial containers like clay pots. Little is known about how these natural versus artificial containers differ in their environments, or whether Ae. aegypti in forest versus domestic habitats evolved any corresponding incipient behavioral divergence, such as in oviposition. To address these gaps, we first characterized physical characteristics, larval density, microbial density, bacterial composition, and volatile profiles of natural versus artificial containers used as mosquito larval breeding sites. We focused on two localities in Africa, La Lopé, Gabon and Rabai, Kenya. In both localities, our data showed that the two habitat-specific container types had significantly different characteristics. We then examined whether such containers differed in their attractiveness for oviposition, a key behavior affecting larval distribution. Forest Ae. aegypti readily accepted artificial containers in our field experiments, and laboratory choice experiments did not find distinct oviposition preference between forest and village Ae. aegypti colonies. These results suggested that African Ae. aegypti were likely generalists in their oviposition site choice. This flexibility to accept different containers might play a vital role during the initial domestication of Ae. aegypti, allowing the mosquitoes to use human-stored water as fallback breeding sites during dry seasons. Although ovipositional changes were not present initially, after longer domestic habitat breeding, the mosquitoes did evolve divergence oviposition preference, as suggested by previous comparisons of African Ae. aegypti and human-specialized non-African Ae. aegypti.