State Key Laboratory of Explosion Science and Technology, Beijing Institute of Technology, Beijing 100081, China; Functional Morphology and Biomechanics, Zoological Institute, Kiel University, Kiel 24118, Germany.
State Key Laboratory of Explosion Science and Technology, Beijing Institute of Technology, Beijing 100081, China.
J Insect Physiol. 2019 Oct;118:103936. doi: 10.1016/j.jinsphys.2019.103936. Epub 2019 Aug 29.
Worker honeybees (Apis mellifera) are morphologically four-winged, but are functionally dipterous insects. During flight, their fore- and hindwings are coupled by means of the forewing posterior rolled margin (PRM) and hindwing hamuli. Morphological analysis shows that the PRM can be connected to the hamuli, so that the fore- and hindwing are firmly hinged, and can rotate with respect to each other. In the present study, using a combination of scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM), we investigate the micromorphology and material composition of the coupling structures on both fore- and hindwings. High-speed filming is utilized to determine the angle variation between the fore- and hindwings in tethered flight. Using sets of two-dimensional (2D) computation fluid dynamic analyses, we further aim to understand the influence of the angle variation on the aerodynamic performance of the coupled wings. The results of the morphological investigations show that both PRM and hamuli are made up of a strongly sclerotized cuticle. The sclerotized hinge-like connection of the coupling structure allows a large angle variation between the wings (135°-235°), so that a change is made from an obtuse angle during the pronation and downstroke to a reflex angle during the supination and upstroke. Our computational results show that in comparison to a model with a rigid coupling hinge, the angle variation of a model having a flexible hinge results in both increased lift and drag with a higher rate of drag increase. This study deepens our understanding of the wing-coupling mechanism and functioning of coupled insect wings.
工蜂（Apis mellifera）在形态上是四翅的，但在功能上是双翅目昆虫。在飞行过程中，它们的前翅和后翅通过前翅后缘卷曲（PRM）和后翅钩连接在一起。形态学分析表明，PRM 可以与钩连接，使前翅和后翅牢固地铰接，并可以相互转动。在本研究中，我们结合扫描电子显微镜（SEM）和共聚焦激光扫描显微镜（CLSM），研究了前翅和后翅耦合结构的微观形态和材料组成。高速拍摄用于确定系留飞行中前翅和后翅之间的角度变化。利用两组二维（2D）计算流体动力学分析，我们进一步旨在了解角度变化对耦合翅膀空气动力学性能的影响。形态学研究的结果表明，PRM 和钩都是由强硬化表皮组成的。耦合结构的硬化铰链连接允许翅膀之间的大角度变化（135°-235°），因此在旋前和下冲程中从钝角变为反射角，在旋后和上冲程中从钝角变为反射角。我们的计算结果表明，与具有刚性耦合铰链的模型相比，具有柔性铰链的模型的角度变化导致升力和阻力都增加，阻力增加的速度更高。这项研究加深了我们对昆虫翅膀耦合机制和耦合翅膀功能的理解。
