The epiphytic orchid Luisia teres (Asparagales: Orchidaceae) releases floral scent that attracts males of the cupreous polished chafer Protaetia pryeri pryeri (Coleoptera: Scarabaeidae) for pollination. We analyzed this floral scent to identify the attractant(s). When various flower parts were extracted with diethyl ether and assayed, male chafers were attracted to the extract of petals but not to that of sepals or lips. The petal extracts were chromatographed on silica gel column and the activity was found in ether and methanol fractions. Gas chromatography/mass spectrometry (GC/MS) analyses and subsequent NMR analyses revealed that both active fractions contained 2,3-dihydroxypropyl isovalerate (2,3-DHPiV) as a major compound. Natural 2,3-DHPiV showed identical retention time to that of synthetic (R)-enantiomer in subsequent HPLC analyses using a chiral column, while (S)-enantiomer was not detected. The amount of this compound was ca. 5 µg/flower. In field tests performed in Okinawa, Japan, males of P. pryeri pryeri were observed to fly around and land on a cotton ball impregnated with synthetic (R)-2,3-DHPiV, but no male was attracted to the (S)-enantiomer or the racemic mixture. Thus, the chemical attractant released from the flower was identified to be (R)-2,3-DHPiV. 2,3-DHPiV was also found in a volatile sample collected from the virgin females by GC/MS analyses using achiral column, while this compound did not occur in males. Because of the difficulty in HPLC detection of a small amount of 2,3-DHPiV, the chirality remains to be determined. Nevertheless, these results strongly suggest that the flowers of L. teres release the same compound as females of its pollinator P. pryeri pryeri, indicating that the flower of this orchid chemically mimics the female sex pheromone.

中文翻译：

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兰花Luisia teres是否通过性欺骗吸引了其男性金龟子授粉媒介（Scarabaeidae：Protaetia pryeri pryeri）？

附生兰花Luisia teres（Asparagales：Orchidaceae）释放出花香，吸引了抛光的铜制金龟子的男性Protaetia pryeri pryeri（鞘翅目：金龟科）进行授粉。我们分析了这种花香，以识别引诱剂。当用二乙醚提取各种花朵部分并进行分析时，雄金龟子会被吸引到花瓣的提取物中，而不是萼片或嘴唇的提取物中。将花瓣提取物在硅胶柱上进行色谱分离，并在乙醚和甲醇馏分中发现其活性。气相色谱/质谱（GC / MS）分析和随后的NMR分析显示，两个活性级分均包含2,3-二羟丙基异戊酸酯（2,3-DHPiV）作为主要化合物。天然2,3-DHPiV在随后的手性色谱柱HPLC分析中显示与合成（R）-对映异构体相同的保留时间，而（S未检测到-对映体。该化合物的量为约。5微克/朵。在日本冲绳进行的田间试验中，观察到P. pryeri pryeri的雄性飞来飞去并着落在浸渍有合成（R）-2,3-DHPiV的棉球上，但没有雄性被吸引到（S）对映异构体或外消旋混合物。因此，从花中释放出的化学引诱剂被确定为（R）-2,3-DHPiV。还通过非手性色谱柱通过GC / MS分析从原始女性收集的挥发性样品中发现了2,3-DHPiV，而该化合物在男性中没有出现。由于难以用HPLC检测少量的2,3-DHPiV，因此手性尚待确定。然而，这些结果强烈表明，L。teres的花释放出与其授粉媒介P. pryeri pryeri的雌性相同的化合物，表明该兰花的花化学上模仿了雌性性信息素。