The Hydraulic Mechanism of the Unfolding of Hind Wings in Dorcus titanus platymelus (Order: Coleoptera)

Abstract

In most beetles, the hind wings are thin and fragile; when at rest, they are held over the back of the beetle. When the hind wing unfolds, it provides the necessary aerodynamic forces for flight. In this paper, we investigate the hydraulic mechanism of the unfolding process of the hind wings in Dorcus titanus platymelus (Oder: Coleoptera). The wing unfolding process of Dorcus titanus platymelus was examined using high speed camera sequences (400 frames/s), and the hydraulic pressure in the veins was measured with a biological pressure sensor and dynamic signal acquisition and analysis (DSA) during the expansion process. We found that the total time for the release of hydraulic pressure during wing folding is longer than the time required for unfolding. The pressure is proportional to the length of the wings and the body mass of the beetle. A retinal camera was used to investigate the fluid direction. We found that the peak pressures correspond to two main cross-folding joint expansions in the hind wing. These observations strongly suggest that blood pressure facilitates the extension of hind wings during unfolding.

The hydraulic mechanism in the hind wing veins of Cybister japonicus Sharp (order: Coleoptera)

“…1 . The exocuticle, endocuticle, and epidermis layers appear brown and light pink (the thin basement membrane), respectively, in a manner similar to that found in [20]. It was shown that vein cavities are irregularly shaped, and their cross-section cavities get smaller and smaller.…”

“…Microstructure testing was conducted in a manner similar to that described in [20]. The microstructures of the cross sections of hind wing veins were captured using an inverted fluorescence microscope (OLYMPUS, LX71).…”

“…A biological pressure sensor and dynamic signal acquisition and analysis (DSA) were designed as a control system to investigate the variation of fluid pressure in the veins of the hind wings [20]. …”

“…In a previous work [20], we investigated the various hydraulic forces for the unfolding process of the hind wings in Dorcus titanus platymelus (Lucanidae, Coleoptera), which is a xylosaprophagous beetle, and its hind wings are folded down to 55% of their full length. In this paper, the hydraulic mechanism in the veins of hind wings of diving beetles ( C. japonicus ) was investigated, and the unfolding process, including blood flow and pressure changes, was simulated.…”

Investigation of hindwing folding in ladybird beetles by artificial elytron transplantation and microcomputed tomography

“…Researchers have found that the intrinsic elasticity acting in wing veins allows this high-speed wing deployment (1)(2)(3)(4)(5)(6). Investigation in other species of beetles indicated the existence of a hydraulic mechanism that straightens the wing veins (7). In contrast, the other fundamental problem, namely, the mechanism behind the folding of these wings, remains unclear.…”