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.

中文翻译：

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蜜蜂的前-后耦合的结构，特性和功能。

工蜂（Apis mellifera）在形态上是四翼昆虫，但在功能上是双翅昆虫。在飞行过程中，它们的前翼和后翼通过前滚后滚缘（PRM）和后翼哈姆利人耦合。形态分析表明，PRM可以连接到哈米利犬上，因此前翅和后翅牢固地铰接在一起，并且可以相对旋转。在本研究中，结合使用扫描电子显微镜（SEM）和共焦激光扫描显微镜（CLSM），我们研究了前翼和后翼的耦合结构的微观形态和材料组成。利用高速摄影来确定系留飞行中前翼和后翼之间的角度变化。使用二维（2D）计算流体动力学分析集，我们进一步旨在了解角度变化对耦合机翼空气动力性能的影响。形态学研究的结果表明，PRM和哈米利都是由强烈硬化的表皮组成。联接结构的硬化铰链状连接允许机翼之间的大角度变化（135°-235°），从而使从旋前和下行程时的钝角更改为仰卧和上行程时的反射角。我们的计算结果表明，与具有刚性连接铰链的模型相比，具有柔性铰链的模型的角度变化会导致升力和阻力都增加，并且阻力增加的速率更高。这项研究加深了我们对昆虫耦合的机翼耦合机制和功能的理解。