Abstract
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.