| | title
Insect aquaplaning: Nepenthes pitcher plants capture prey with the peristome, a fully wettable water-lubricated anisotropic surface
abstract
Pitcher plants of the genus Nepenthes have highly specialized leaves adapted to attract, capture, retain, and digest arthropod prey. Several mechanisms have been proposed for the capture of insects, ranging from slippery epicuticular wax crystals to downward-pointing lunate cells and alkaloid secretions that anesthetize insects. Here we report that perhaps the most important capture mechanism has thus far remained overlooked. It is based on special surface properties of the pitcher rim (peristome) and insect "aquaplaning." The peristome is characterized by a regular microstructure with radial ridges of smooth overlapping epidermal cells, which form a series of steps toward the pitcher inside. This surface is completely wettable by nectar secreted at the inner margin of the peristome and by rain water, so that homogenous liquid films cover the surface under humid weather conditions. Only when wet, the peristome surface is slippery for insects, so that most ant visitors become trapped. By measuring friction forces of weaver ants (Oecophylla smaragdina) on the peristome surface of Nepenthes bicalcarata, we demonstrate that the two factors preventing insect attachment to the peristome, i.e., water lubrication and anisotropic surface topography, are effective against different attachment structures of the insect tarsus. Peristome water films disrupt attachment only for the soft adhesive pads but not for the claws, whereas surface topography leads to anisotropic friction only for the claws but not for the adhesive pads. Experiments on Nepenthes alata show that the trapping mechanism of the peristome is also essential in Nepenthes species with waxy inner pitcher walls.
source
Bohn HF, Federle W. Proc Natl Acad Sci U S A. 2004, 101: 14138-14143.
link
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=15383667&query_hl=10&itool=pubmed_docsum
標題
滑水的昆蟲：豬籠草以完全可以用水潤溼的向異性表面的唇來捕捉獵物
摘要
瓶子類的植物中，豬籠草具有高度特化的葉子以適用於吸引、捕捉、攔住，並消化節肢動物類的獵物。已有數種捕蟲的機制被提出來了，從光滑表面上的臘結晶到朝向底部的新月形細胞，以及可麻醉昆蟲的植物鹼分泌物。在此我們所要報導的，或許最重要的捕蟲機制從長久以來就被忽略了。這捕蟲機制是基於瓶子唇部的特殊表面特性及昆蟲的「滑水」。豬籠草的唇是由帶有放射狀脊形的光滑表皮細胞相疊成連續而朝向瓶內的臺階，而形成有規則性微小結構這樣的特徵。這樣的表面是可由位在唇的內側邊緣的蜜腺的分泌和雨水而完全弄溼。因此，在潮溼氣候的狀態下，唇的表面上會覆蓋一層均一的液體薄膜。只有在潮溼的狀態下，唇的表面才會讓蟲滑落。藉由測量編織蟻(Oecophylla smaragdina)在二齒豬籠草的唇上的磨擦力，我們證明了有兩種因子會防止昆蟲附著在唇上，也就是說，水的潤滑作用和異向性表面形貌都能有效地抵制昆蟲腳指上不同處的附著面。唇的水膜對昆蟲附著能力的破壞只對軟的肉墊(譯注：例如毛毛蟲的腳)有效，但對爪子確是無效的。反之，表面形態所帶來的異向性磨擦力只會使爪子抓不住，但不會影響黏性的肉墊。在N. alata上的實驗顯示，豬籠草帶有臘的內側瓶壁對唇的捕蟲機制亦是不可或缺的。
| | |
|
|
|
頂端 
加到"我的最愛"
主題管理：
總固頂 
取消總固頂 
Message
查看
搜尋
通訊錄
複製
引用
回覆
2006/01/16 06:37pm 
IP: 已設定保密