Dispersal of adult aquatic Chironomidae (Diptera) in agricultural landscapes

1. This study investigates the possible influence of terrestrial landscape structure on the spatial distribution of adult Chironomidae emerging from water bodies in three agricultural areas, each with hedgerow networks, in Brittany (France). 2. Using spatially explicit data from 128 yellow pan traps set in pairs at the bottom of hedges throughout the three study areas, we show that landscape structure and heterogeneity must be considered at two different spatial scales. 3. At a global scale, distance to water bodies was the main factor explaining the spatial distribution of adult chironomids: both species richness and abundance changed beyond a critical distance to the stream, resulting in different species assemblages of flying insects. 4. At a local scale, the abundance of species and individuals at rest in hedges changed with the quality of the hedge (mainly determined by canopy width and cover of the different vegetation layers). 5. The density of the hedgerow network, and landscape openness, both influenced the dispersal of chironomid species from water bodies. 6. This study, which provides the first estimate of the dispersal capabilities of chironomids in particular landscapes, suggests that the terrestrial environment is an essential component of population dynamics and community structure in aquatic Chironomidae.