The authors present a thorough study on the distribution of resilin-bearing wing vein joints in wings of Odonata. 22 species of 20 different families of dragonflies and damselflies, showing various wing morphologies and flight kinematics, are examined and reveal interesting evolutionary trends.
Dragonflies and damselflies show an exceptional high lift production and are some of the most maneuverable flying insects. The important role of their corrugated wing profile in increasing lift production has been shown in various studies. As odonate wings lack internal muscles, their aerodynamic performance relies on passive deformations, such as pleat angle widening and camber formation. The rubber-like protein resilin has been shown to play a crucial role in wing joint flexibility. Thus, it may be assumed that the specific distribution of either stiff or flexible, resilin-bearing vein joints may influence the overall wing deformation during flight.
Using fluorescence light microscopy and scanning electron microscopy, the dorsal and ventral wing sides of different species are compared with respect to the distribution patterns of four types of vein joints, five types of resilin patches, and joint-associated spines. The results reveal a significant difference between dragonflies and damselflies. Variations of the distribution patterns suggest a classification into five different pattern groups. Their occurrence within the two suborders shows some evolutionary trends and gives insight into the wing functionality. In particular, we discussed how the combination of joint morphology, kinematics, and wing morphology may allow different passive wing deformations during flight.
This study, generously illustrated with 53 mostly coloured figures is of great interest to biologists studying insect flight, functional morphology, and evolution of Odonata. Furthermore, the described distribution patterns of different vein joints in combination with wing shape and flight kinematics may possibly inspire their biomimetic imitation in micro air vehicles (MAV).
1 Introduction 2
1.1 Motivation 2
1.2 A corrugated wing design 2
1.3 Resilin, a rubberlike protein, in insect flight systems 3
1.4 Artificial flight systems inspired by dragonfly wings 3
1.5 Aim of the study 3
2 Material and Methods 4
2.1 Animals 4
2.2 Fluorescence light microscopy (FLM) 4
2.3 Scanning electron microscopy 5
3 Results 5
3.1 Types of vein joints and joint combinations 5
3.2 Spines 6
3.3 Resilin in dragonfly and damselfly wings 7
3.4 Correlation between the joint type and resilin patch type 7
3.5 Comparative analysis of the distribution of spines, resilin patch and joint types in different taxa of Odonata 8
3.5.1 Distribution of spines, resilin patch types and joint types in different taxa of Odonata 8
3.5.2 Phylogenetic comparison of different structures 21
3.5.2.1 Five groups based on wing joint structures 22
3.5.2.2 General constructional trends 23
4 Discussion 24
4.1 Role of resilin-bearing joint combinations and lateral resilin patches in the deformability of wing parts 24
4.2 Different functions of resilin 25
4.3 Comparative analysis of wing morphology, behavior, and joint morphology 26
4.3.1 Differences between perchers and fliers 26
4.3.2 Differences between Epiprocta and Zygoptera 26
4.3.3 Differences among the suborders 28
4.4 Functional role of spines 30
5 Conclusions 30
6 Outlook 31
Acknowledgements 31
References 31
Appendix – List of taxa studied 102