Vertical distribution of Stomoxys spp. (Diptera: Muscidae) in a rainforest area of Gabon

The vertical distribution of Stomoxys spp. was studied in a rainforest area, Ipassa-Makokou biosphere reserve located in the Ivindo National Park of Gabon. From April to June 2006, Vavoua traps were set out during 15 consecutive days per month at different heights above ground level corresponding to vertical layers of rainforest: 50cm, 10, 20 and 30m. Stomoxys calcitrans, S.transvittatus, S.omega, S.niger niger and S.niger bilineatus were more abundant at near ground level (50cm), whereas abundance of S.xanthomelas was greatest in traps higher (20 and 30m) in the canopy. Fly abundance was significantly different among vertical layers of the forest (H=36.91; P<0.001, ddl=3), and among species to another (H=41.11, P<0.001). Vertical distribution of fly species corroborates feeding behaviour as the identification of blood meal origins showed heterogeneity of feeding hosts. High densities of flies were also observed at 10m, and most S.inornatus were captured at that level. These results show that Stomoxyine flies in this rainforest are present in all vertical layers, from the ground level to the canopy. Their ubiquity, regarding both their habitats and their hosts, should be taken into account if a vector control strategy is planned in this touristic area.