Bauer Ulrike, Willmes Christoph, Federle Walter
Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK.
Ann Bot. 2009 Jun;103(8):1219-26. doi: 10.1093/aob/mcp065. Epub 2009 Mar 22.
Nepenthes pitchers are sophisticated traps that employ a variety of mechanisms to attract, capture and retain prey. The underlying morphological structures and physiological processes are subject to change over the lifetime of a pitcher. Here an investigation was carried out on how pitcher properties and capture efficiency change over the first 2 weeks after pitcher opening.
Prey capture, trapping efficiency, extrafloral nectar secretion, pitcher odour, as well as pH and viscoelasticity of the digestive fluid in N. rafflesiana pitchers were monitored in the natural habitat from pitcher opening up to an age of 2 weeks.
Pitchers not only increased their attractiveness over this period by becoming more fragrant and secreting more nectar, but also gained mechanical trapping efficiency via an enhanced wettability of the upper pitcher rim (peristome). Consistently, natural prey capture was initially low and increased 3-6 d after opening. It was, however, highly variable within and among pitchers. At the same time, the pH and viscoelasticity of the digestive fluid decreased, suggesting that the latter is not essential for effective prey capture.
Prey capture and attraction by Nepenthes are dynamic processes strongly influenced by the changing properties of the pitcher. The results confirm insect aquaplaning on the peristome as the main capture mechanism in N. rafflesiana.
猪笼草的捕虫笼是复杂的陷阱，运用多种机制来吸引、捕获并留住猎物。其潜在的形态结构和生理过程在捕虫笼的生命周期中会发生变化。在此，我们对捕虫笼开放后的前两周内，捕虫笼特性及捕获效率如何变化展开了研究。
在自然栖息地中，对莱佛士猪笼草捕虫笼从开放直至两周龄期间的猎物捕获情况、诱捕效率、花外蜜分泌、捕虫笼气味，以及消化液的pH值和粘弹性进行了监测。
在此期间，捕虫笼不仅通过变得更香和分泌更多花蜜来提升自身吸引力，还通过增强捕虫笼上部边缘（唇）的润湿性提高了机械诱捕效率。同样，自然状态下的猎物捕获量起初较低，在开放后3 - 6天增加。然而，在各个捕虫笼内部及不同捕虫笼之间，捕获量差异很大。与此同时，消化液的pH值和粘弹性下降，这表明消化液对于有效捕获猎物并非必不可少。
猪笼草的猎物捕获和吸引是动态过程，受捕虫笼不断变化的特性强烈影响。结果证实，昆虫在唇上的水滑作用是莱佛士猪笼草的主要捕获机制。
