Abstract
Abstract
Background
The mechanisms underlying oviposition site selection by malaria vectors remain poorly understood. Understanding the behavioural cues that guide gravid mosquitoes in selecting breeding habitats is essential for developing improved surveillance and vector control tools, particularly those targeting gravid females and aquatic stages.
Methods
Laboratory colonies of
Anopheles gambiae
s.s. and
Anopheles arabiensis
were reared separately in water collected from two natural breeding habitats in Muheza District, Tanzania, and in dechlorinated laboratory tap water. Upon becoming gravid, females from each rearing group were simultaneously offered three oviposition substrate choices corresponding to the different rearing waters under both laboratory cage bioassays and semi-field mosquito sphere experiments. Oviposition preference was determined by comparing the proportion of eggs deposited in each substrate.
Results
A total of 1,080 gravid mosquitoes were evaluated under laboratory conditions and 3,600 under semi-field conditions. Both
An. gambiae
s.s. and
An. arabiensis
demonstrated a tendency to oviposit preferentially in water resembling their natal habitat. In laboratory assays,
An. arabiensis
showed significant preference for its natal habitat water when reared in natural breeding-site substrates, while
An. gambiae
s.s. exhibited significant preference for both natal natural habitat and laboratory-rearing water. Semi-field experiments showed similar behavioural trends, although the responses were less consistent because of increased environmental variability. Overall, the results indicate that larval experience significantly influences oviposition site selection in adult mosquitoes.
Conclusions
These findings suggest that exposure to natal habitat odours during larval development influences subsequent oviposition site selection by adult mosquitoes. Natal habitat odours therefore represent promising semiochemicals candidates for improving gravid mosquito surveillance and control.