Data from: Material composition of the mouthpart cuticle in a damselfly larva (Insecta: Odonata) and its biomechanical significance

Odonata larvae are key predators in their habitats. They catch prey with a unique and highly efficient apparatus, the prehensile mask. The mandibles and maxillae, however, play the lead in handling and crushing the food. The material composition of the cuticle in the biomechanical system of the larval mouthparts has not been studied so far. We used confocal laser scanning microscopy (CLSM) to detect material gradients in the cuticle by differences in autofluorescence. Our results show variations of materials in different areas of the mouthparts: (i) resilin-dominated pads within the membranous transition between the labrum and the anteclypeus, which support mobility and might provide shock absorption, an adaptation against mechanical damage; (ii) high degrees of sclerotisation in the incisivi of the mandibles, where high forces occur when crushing the prey's body wall. The interaction of the cuticle geometry, the material composition, and the related musculature determines the complex concerted movements of the mouthparts. The material composition influences the strength, mobility and durability of the cuticular components of the mouthparts. Applying CLSM for extracting information about material composition and material properties of arthropod cuticles will considerably help improve FEM studies.

蜻蛉目（Odonata）幼虫是其栖息生境中的关键捕食类群。它们依托一套独特且高效的捕食器官——可动捕食面具（prehensile mask）捕获猎物。不过，上颚（mandibles）与下颚（maxillae）才是处理、粉碎食物的核心结构。截至目前，针对幼虫口器生物力学系统中角质层（cuticle）的物质组成，相关研究仍处于空白状态。本研究采用共聚焦激光扫描显微镜（confocal laser scanning microscopy，CLSM），通过自发荧光差异检测角质层内的物质梯度分布。研究结果显示，口器不同区域的物质组成存在显著差异：其一，上唇（labrum）与前唇基（anteclypeus）之间的膜状过渡区域存在以节肢弹性蛋白（resilin）为主要成分的垫状结构，该结构可辅助运动并可能起到缓冲减震作用，属于抵御机械损伤的适应性特征；其二，上颚切齿区存在高度骨化（sclerotisation）的结构，该区域在粉碎猎物体壁时需承受极高作用力。角质层的几何形态、物质组成与相关肌肉系统的协同作用，共同决定了口器复杂的协调运动模式。物质组成直接影响口器角质层组分的强度、运动性与耐用性。利用共聚焦激光扫描显微镜获取节肢动物角质层的物质组成与力学特性信息，将对优化有限元法（Finite Element Method，FEM）相关研究起到显著推动作用。