The wing morphology of limnephilid caddisflies in relation to their habitat preferences

Abstract

Summary The aerial dispersal of merolimnic insects is a prerequisite for maintaining metapopulations and for colonising new habitats. Flight morphology, as one determinant of dispersal capacity, may be related to the distribution patterns and ecological preferences of aquatic insects, but empirical data for Trichoptera are scarce. This study aimed to provide flight morphological data for common European Trichoptera species in relation to their ecological preferences. We measured the flight morphology of 26 Central European species of Limnephilidae (Trichoptera) including wing length, wing width, wing area, relative wing length and the aspect ratio of the fore and hind wings (combined). There were strong relationships between forewing length and body length (r² = 0.884), wing width (r² = 0.960) and wing area (r² = 0.93) in the untransformed data. Species of the same genus may differ strongly in wing length, wing width and wing area; however, when the wing area is considered on the size‐independent scale of relative wing length, species of the same genus are more similar. Sexual dimorphism was species specific. Male wing dimensions exceeded those of females in all species that displayed significant differences between the sexes except in Parachiona picicornis. For aerodynamic indices such as aspect ratio, only 28 % of the studied species show sexual dimorphism; in Limnephilus fuscicornis and Potamophylax luctuosus, males exceed females, and in Drusus annulatus, Drusus discolor and Potamophylax cingulatus, females exceeded males. On the basis of our data, we conclude that females may be the primary dispersers in four of the 18 species for which sufficient data were available, whereas in two species males appear to be stronger dispersers. We found three different morphological blueprints in forewing length and wing width: Group 1 encompassed crenal‐inhabiting species with a distinct habitat preference for mineral habitats (low aspect ratio, small wings; e.g. D. discolor); group 2 comprised rhithral species without a distinct habitat preference (high aspect ratio, large wings; e.g. P. cingulatus); and group 3 encompassed species inhabiting lentic waters and preferring organic habitats (high aspect ratio, medium‐sized wings; e.g. Anabolia nervosa).