琴唇万代兰食源性欺骗传粉研究

食源性欺骗传粉是兰科植物的一种重要传粉机制。根据琴唇万代兰的花部特征及较低的自然结实率,我们推测其有性繁殖采取食源性欺骗传粉机制,为了验证推测,在广西雅长兰科植物国家级自然保护区对其进行传粉生物学观察。野外传粉观察结果表明:琴唇万代兰花朵自交高度亲和,但其传粉过程依赖于传粉昆虫;赤足木蜂和牯岭熊蜂都是琴唇万代兰的有效传粉昆虫,其中赤足木蜂为主要传粉昆虫;2种传粉昆虫的访花行为主要集中在2个阶段:68%发生在10:00—12:30,16%发生在13:30—14:30。周边与琴唇万代兰同期开花的植物有阔叶十大功劳和中国旌节花,阔叶十大功劳花朵为明亮的黄色,与琴唇万代兰花朵上斑块的颜色相近。我们认为琴唇万代兰花朵通过挥发芳香性气味和利用花朵上黄色斑块等特征来欺骗传粉昆虫进入花中觅食,实现有效传粉的目的,为食源性欺骗传粉机制。 

Food-deceptive pollination of Vanda concolor(Orchidaceae)

Food-deceptive pollination is one of the significant pollination mechanisms among orchids. Given floral syndromes and low natural fruit setting rate of Vanda concolor, we assume that this orchid species is in compliance with a food-deceptive pollination mechanism. In order to test our assumption, we investigated pollination biology of V. concolor during 2012-2013 in the Yachang National Nature Reserve, which is located in northwestern Guangxi, China. Our observations confirmed that the flowers were self-compatible but required floral visitors. Both Xylocopa rufipes and Bombus kulingensis are effective pollinators with the former more effective than the latter. Foraging in the flowers mainly occurred in two periods: 68% in 10:00 am—12:30 pm and 16% in 13:30 pm—14:30 pm. Mahonia beaill, Stachyurus chinensis and Vanda concolor have the same flowering season in the study area, and the bright yellow color of Mahonia beaill flowers is similar to the color of spots on Vanda concolor flowers. Five chemical compounds have been identified as the volatile constituents of flower fragrance of the orchid, of which 1,6,10-dodecatrien-3-ol,3,7,11-trimethyl-,(E)-(29.6%) and cinnamaldehyde,(E)-(27.0%) are the most abundant compounds. We consider that the plant attracts pollinators into flowers for foraging by floral fragrance and yellow spots in flowers, and it follows the food-deceptive pollination mechanism.