2010年2月8日 星期一

蝴蝶喝珍奶!奶茶哪裡來?

文獻來源:SH EBERHARD,AL HIKL,CL BOGGS, AND HW KRENN. 2009. Saliva or Regurgitated Nectar? What Heliconius Butterflies (Lepidoptera: Nymphalidae) Use for Pollen Feeding. Ann. Entomol. Soc. Am. 102(6): 1105-1108 [link]

人們已經知道新熱帶的Heliconius屬蝴蝶會攝取花粉以補充其以蜜源為主的菜單,他們從花 粉粒中得到蛋白質與氨基酸,伴隨著利用來源不明的液體以便攝入花粉的行為。由於解剖學上的證據顯示蝴蝶只能透過口器釋放出唾液或是反芻的花蜜,故此未知來 源的液體被假設來自上述兩者。在此研究的試驗一,作者取27隻 Heliconius melpomene (L.) 給予帶有紅色染劑染色的糖水,接著觀察他們排出以幫助攝食花粉的液體是否帶有紅色染劑。試驗二則將H. melpomene分為兩組,分別給予/不給予糖水,然後用蒸餾水洗淨其口器,再給予花粉粒般尺寸的玻璃小珠誘導其攝食花粉的行為,將被口器沾過的玻璃小珠以微量的蒸餾水浸潤沖洗,進行是否含有還原糖的檢測(利用aniline phthalate,可測葡萄糖、果糖,但對蔗糖不產生反應)。試驗三則在哥斯大黎加雨林中捕捉野生個體,測試其口器上是否有還原糖。結果發現,除了試驗二的第一組給予糖水的測試之外,在Heliconius的口器上無法測得還原糖,而在試驗一中吐出的液體為透明無色且甚至可在排遺露滴中觀察到紅色染劑的存在。試驗二第一組少數樣本的差異可能歸因於沾染糖水的足再次接觸接受蒸餾水洗淨的口器,因而造成誤差。因此作者的結論為本研究證明了Heliconius屬蝴蝶攝取花粉食輔助攝食的液體為他的唾液、而非反芻的糖蜜。

ABSTRACT
The Neotropical Heliconius butterflies are well known to supplement their nectar diet by active pollen collecting. They extract proteins and free amino acids from pollen grains, exhibiting a particular behavior that involves the use of a fluid of uncertain origin. It has been assumed that this fluid is either regurgitated nectar or saliva, because for anatomical reasons a butterfly is able to release only these two fluids through its proboscis. In an experimental approach, 27 individuals of Heliconius melpomene (L.) were given red-dyed sugar solution and subsequently we observed whether the fluid used in pollen feeding was dyed or not dyed. Because regurgitated nectar should contain sugar, fluid samples were taken from the proboscis of butterflies from natural populations in Costa Rica. Samples of 44 individuals from seven species were tested for the presence of fructose and glucose with the aid of aniline phthalate. This study is the first detailed investigation of the origin of the fluid used by Heliconius butterflies in pollen feeding. The results are discussed in terms of already existing hints in literature concerning the true nature of that fluid.

KEY WORDS: heliconiines, Laparus, sugar assay, nutritional ecology

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