A Study on Allometry of Wing Shape and Venation in Insects. Part 2. Diptera

Abstract

The research studied how body size affects wing shape and arrangement of veins in a wide range of families of dipteran insects (Diptera). Body mass and thorax length were used as criteria reflecting body size. Wing shape was characterized by aspect ratio and position of geometric center relative to its longitudinal axis. Allometry of venation was studied by geometric morphometric methods. It was found that character of dependence of wing shape on body size among Brachycera and Nematocera is different. Aspect ratio increases with body size in Nematocera, in Brachycera any correlation is absent. Shift of geometric center of a wing towards its base at the increase in body size is observed for Brachycera, for Nematocera no correlation is noted. It was shown that allometric component of the variation in arrangement of veins varies significantly between different families. With increase in body size, for most Brachycera-Cyclorrhapha studied (Calliphoridae, Muscidae, Sarcophagidae, Sepsidae, Tachinidae), shifts of r-m vein in basal direction and dm-cu vein in apical direction are noted. In Brachycera-Orthorrhapha suborder (Asilidae, Dolichopodidae, Empididae, Rhagionidae, Tabanidae), the point of intersection of veins R_{2 + 3} and C shifts towards the apex. For representatives of Nematocera (Chironomidae, Limoniidae, Tipulidae), shifts of the point of intersection of veins CuA₂ and C in basal direction and r-m vein in apical direction are characteristic. The obtained data confirms significant effect of body size on wing shape in Diptera. However, the character of allometry is not uniform in different suborders, apparently due to the fact that values of flight parameters (wing frequency, stroke amplitude), relative wing size (wing area to body size ratio) and wing venation vary greatly in dipterans. It can be concluded that body size is not the principal factor affecting wing shape within the order Diptera.