Sex- and size-dependent variation in wing morphology of the cuckoo wasp Trichrysis cyanea (Hymenoptera: Chrysididae)

Abstract

Intraspecific variation and sexual dimorphism in wing shape and size is common in winged insects. The exact patterns, however, differ among taxa and are related to the selection pressure acting on specific traits. Cuckoo wasps (Chrysdidae) are hymenopterans that have evolved a complex parasitoid or cleptoparasitic life-style. For the first time, we studied the intraspecific variation in wing shape and size in the model species, Trichysis cyanea, a common Palearctic cuckoo wasp. This involved geometric morphometrics combined with a novel, non-invasive way of obtaining images, to study the shape and size of the forewings of males and females. We found clear sexual dimorphism in both wing shape and size, possibly related to fecundity (as wing size typically correlates with body size in many insects) and increased manoeuvrability of females for searching for their host's nesting holes. This study increases our knowledge of the biology of T. cyanea in terms of a better understanding of the evolution of parasitism and corresponding adaptations in this hymenopteran family.

Keywords

• landmark-based geometric morphometrics
• centroid size
• sexual size dimorphism (ssd)
• wing venation
• flight behaviour
• flight performance