Labonte David, Robinson Adam, Bauer Ulrike, Federle Walter
Department of Bioengineering, Imperial College London, UK; Department of Zoology, University of Cambridge, UK.
Department of Zoology, University of Cambridge, UK.
Acta Biomater. 2021 Jan 1;119:225-233. doi: 10.1016/j.actbio.2020.11.005. Epub 2020 Nov 12.
Nepenthes pitcher plants capture prey with leaves specialised as pitfall traps. Insects are trapped when they 'aquaplane' on the pitcher rim (peristome), a surface structured with macroscopic and microscopic radial ridges. What is the functional significance of this hierarchical surface topography? Here, we use insect pad friction measurements, photolithography, wetting experiments and physical modelling to demonstrate that the ridges enhance the trap's efficacy by satisfying two functional demands on prey capture: Macroscopic ridges restrict lateral but enhance radial spreading of water, thereby creating continuous slippery tracks which facilitate prey capture when little water is present. Microscopic ridges, in turn, ensure that the water film between insect pad and peristome remains stable, causing insects to aquaplane. In combination, the hierarchical ridge structure hence renders the peristome wettable, and water films continuous, so avoiding the need for a strongly hydrophilic surface chemistry, which would compromise resistance to desiccation and attract detrimental contamination.
猪笼草通过特化为陷阱的叶子捕捉猎物。昆虫在捕虫笼边缘（唇）“水上滑行”时被困住，唇表面有宏观和微观的径向脊。这种分层表面形貌的功能意义是什么？在这里，我们通过昆虫脚垫摩擦力测量、光刻、润湿实验和物理建模来证明，这些脊通过满足猎物捕获的两个功能需求来提高陷阱的效率：宏观脊限制水的横向扩散但增强其径向扩散，从而形成连续的滑痕，在水很少时便于捕获猎物。微观脊则确保昆虫脚垫和唇之间的水膜保持稳定，使昆虫能够水上滑行。因此，分层的脊结构使唇具有可湿性，水膜连续，从而避免了对强亲水表面化学的需求，否则会损害抗干燥能力并吸引有害污染物。
