The combination of structure and material distribution ensures functionality of the honeybee wing-coupling mechanism

Fore- and hindwings of honeybees are coupled and synchronized to flap by means of a forewing posterior recurved margin (PRM) and hindwing hamuli which constitute a hook-furrow coupling. Morphological analysis shows that the PRM is composed of a thickened and sclerotized membrane with the Archimedean spiral configuration and hamuli are a set of tiny, sclerotized hooks with flexible bases. By developing a theoretical PRM model, the influence of cuticle sclerotization and membrane-thickening on a deforming pattern and maximal coupling force was comparatively simulated, indicating that the real PRM is capable of bearing the highest coupling force and the membrane thickening makes more contribution than cuticle sclerotization on augmenting the maximal coupling force that the PRM can resist. In addition, four combined strategies, i.e. the hook shape, Archimedean spiral, rich resilin concentration, and cuticle sclerotization in different parts of the whole system were proposed, and deemed to endow the honeybee wing-coupling with remarkable stability and durability to eliminate a potential structural failure of the coupling over millions of wing flapping cycles across the honeybee lifespan. This study assists us in the comprehensive understanding of the functionality of the hook-furrow wing-coupling and shows us new avenues for biomimetics of mobile coupling mechanisms in modern engineering.