Functional morphology and evolution of the sting sheaths in Aculeata (Hymenoptera)

摘要

The sting of the Aculeata or stinging wasps is a modifed ovipositor; its function (killing or paralyzing prey, defense against predators) and the associated anatomical changes are apomorphic for Aculeata. The change in the purpose of the ovipositor/sting from being primarily an egg laying device to being primarily a weapon has resulted in modifcation of its handling that is supported by specifc morphological adaptations. Here, we focus on the sheaths of the sting (3rd valvulae = gonoplacs) in Aculeata, which do not penetrate and envenom the prey but are responsible for cleaning the ovipositor proper and protecting it from damage, identifcation of the substrate for stinging, and, in some taxa, contain glands that produce alarm pheromones. The3rd valvulae may be divided into proximal and distal parts. No muscles insert on the 3rd valvulae, and in the process of stinging the movements of the 3rd valvulae are determined by the morphological features of the entire sting apparatus, e.g., the elastic cuticle between the 2nd valvifers and 3rd valvulae and also between the sclerites of the 3rd valvulae. The return of the 3rd valvulae to their resting position is facilitated by the presence of resilin-like proteins in these junctions. The structure and movements of the 3rd valvulae are discussed in the context of the sting function in various groups of Aculeata. The evolution of the 3rd valvulae is discussed; a secondary simplifcation of the 3rd valvulae structure is observed in representatives of Vespidae, Formicidae, Colletidae, Apidae, Melittidae.