Life history consequences of larval foraging depth differ between two competingAnopheles mosquitoes

Abstract

1. Anopheline larvae are surface feeders and allocate most of their time to search for food at the water surface. However, species of theAnopheles gambiaeGiles complex may also show bottom feeding. The consequences of this foraging tactic for life history are unknown, yet may be relevant to understand inter‐specific competition patterns.2. The diving ability and activity of larvae of the mainAfrican malaria vectors,An. coluzziiandAn. gambiae, at two different water depths (14 and 30 cm) were assessed. We further explored the biological relevance of diving for food harvesting by monitoring key life history traits in two species treatments (single or mixed species) and two food treatments (surface or bottom feeding).3. Overall,An. coluzziilarvae showed more diving activity thanAn. gambiae. When feeding at the bottom both species, and especiallyAn. gambiae, showed a delayed emergence and a reduced emergence rate. Moreover,An. gambiaealso suffered a reduced wing length.4. Mixed‐species rearing had a detrimental effect on the life history traits ofAn. gambiaebut not onAn. coluzzii, suggesting a competitive advantage for the latter in our experimental conditions.5. The present results confirm that anopheline larvae are able to forage for food at the bottom of their breeding site and thatAn. coluzziishows a superior diving activity thanAn. gambiaeand this at a lower cost. These behavioural differences probably reflect specific adaptations to different aquatic habitats, and may be important in shaping species distributions and the population biology of these important vector mosquitoes.