Possible ways of wing vein reduction in Aphidiinae (Hymenoptera: Braconidae)

Abstract

Wing vein reduction occurs in many Braconidae subfamilies, especially in Euphorinae and also Aphidiinae, one of the well investigated groups of parasitic wasps. We explored wing venation patterns of 55 species from 13 genera of Aphidiinae covering almost all types of wing venation within the subfamily Aphidiinae. To explain the phylogenetic background of wing vein reduction we used a landmark-based geometric morphometrics method and a phylogenetic comparative analysis. Thus, we tested whether evolutionary changes in wing shape correlate to the changes in wing venation and whether both changes depend on the size of the wings. With different degrees of vein reduction which can be observed in analyzed Aphidiinae taxa, eight wing venation types are recognized and defined. We found that the Ephedrus wing venation type is basic for Aphidiinae from which three directions of vein reduction can be explained. Generally, wing venation type is largely genus specific, except in the case of much reduced wing venation which could be found across the examined Aphidiinae taxa. The reconstruction of evolutionary changes in wing venation indicates that changes in wing vein distribution, also the whole wing shape are related to the changes in general wing size. We also noted that wings with much reduced wing venation (only radial vein left) and maximally reduced wing venation (no veins in the distal part) affect stigma; shortening its length making it more or less triangular; which can be connected with the theory of miniaturization of the insect body, or some morphological structures. Based on the results, it seems that the reduced wing venation have evolved independently in the subfamily several times.