Department of Functional Morphology and Biomechanics, Institute of Zoology, Christian-Albrechts-Universität zu Kiel, Am Botanischen Garten 1-9, D-24118 Kiel, Germany.
Nat Commun. 2013;4:1661. doi: 10.1038/ncomms2576.
For an insect to be able to efficiently attach to surfaces, the adhesive pads on the distal parts of its legs must establish large contact areas. In case of hairy adhesive pads this requires flexibility of the contact-forming bristles, called adhesive tarsal setae. However, too flexible setae would have a low mechanical stability resulting in a decreased attachment ability of the pads. Here we show that the adhesive tarsal setae of the ladybird beetle Coccinella septempunctata feature pronounced gradients in the material composition and properties along their length. The Young's modulus ranges from 1.2 MPa at the tips, where we found the incorporation of high proportions of the elastic protein resilin, to 6.8 GPa at the bases of the setae. These gradients likely represent an evolutionary optimization, which increases the performance of the adhesive system by enabling effective adaptation to rough surfaces while simultaneously preventing lateral collapse of the setae.
为了使昆虫能够有效地附着在表面上，其腿部远端的粘性垫必须建立大的接触面积。在有毛粘性垫的情况下，这需要接触形成的刚毛的柔韧性，这些刚毛称为粘性跗节刺毛。然而，过于灵活的刺毛将具有较低的机械稳定性，从而导致垫的附着能力降低。在这里，我们表明，七星瓢虫（Coccinella septempunctata）的粘性跗节刺毛在其长度上表现出明显的材料组成和性能梯度。杨氏模量范围从尖端的 1.2 MPa 开始，在那里我们发现了高比例的弹性蛋白减震蛋白的掺入，到刺毛基部的 6.8 GPa。这些梯度可能代表了一种进化优化，通过使粘性系统能够有效地适应粗糙表面，同时防止刺毛的侧向坍塌，从而提高了粘性系统的性能。
