Causes of variation in wing loading among Drosophila species

We examined influences on wing and body size in 11 species (12 strains) of Drosophila. Six measures of wing length and width were closely correlated with wing area and suggested little variation in wing shape among the species. Among ten species wing loading, an important factor in flight costs and manoeuvrability, increased as body mass increased at a rate consistent with expectations from allometric scaling of wing area and body mass to body length. Intraspecific variation in wing loading showed similar relationships to body mass. Density and temperature during larval development influenced wing loading through general allometric relations of body size and wing area. Temperature during the pupal stage, but not during wing hardening after eclosion, influenced wing area independently of body size. Wing area increased as growth temperature decreased. Individuals reared at cooler temperatures thus compensated for a potential allometric increase in wing loading by differentially enlarging the wing area during pupal development.