Mouthpart dimorphism in male and female wasps of Vespula vulgaris and Vespula germanica (Vespidae, Hymenoptera)

Bianca Baranek,Julia Bauder,Kenneth Kuba,Harald Krenn

doi:10.3897/dez.65.23593

Abstract

Social wasps perform a variety of tasks with their mouthparts. Female workers use them to feed on carbohydrate-rich fluids, to build nests by collecting wood fibers and forming paper, to hunt and manipulate insect prey for feeding larvae as well as for brood care. Since male wasps neither feed on insects nor participate in nest building, sex-specific differences in mouthpart morphology are expected. Despite these different applications, general mouthpart morphology of male and female wasps from the genus Vespula was similar. However, males possessed significantly shorter mandibles with fewer teeth than females. Furthermore, the adductor muscles of the mandibles were distinctly smaller in males than in females. Male wasps showed a higher number of sensilla on the mandibles and the labial palpi. Mouthpart dimorphism and functional morphology of fluid uptake are discussed.

Highlights

Insect mouthparts are composed of a set of homologous organs that are derived from appendages of head segments adapted to various tasks in context of feeding, defence and nesting
In social wasps, the mouthparts are functionally versatile allowing their use in various kinds of tasks that are reflected by the well-developed biting mandibles and the labio-maxillary complex which is used to take up nectar and other kinds of fluids (Schremmer 1962)
No differences in head and mouthpart morphology were found between V. vulgaris and V. germanica (Fig. 1)

Summary

Introduction

Insect mouthparts are composed of a set of homologous organs that are derived from appendages of head segments adapted to various tasks in context of feeding, defence and nesting. The mandibulate mouthparts of Hymenoptera are characterized by the labio-maxillary complex which is formed by components of the labium and the maxillae (Duncan 1939, Krenn et al 2005). This unique functional unit of the mouthparts as well as the four-segmented labial palpus are regarded as autapomorphies of the Hymenoptera (Krenn 2007). In social wasps, the mouthparts are functionally versatile allowing their use in various kinds of tasks that are reflected by the well-developed biting mandibles and the labio-maxillary complex which is used to take up nectar and other kinds of fluids (Schremmer 1962)

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Results

Conclusion