Department Urban Plant Ecophysiology, Humboldt-Universität zu Berlin, Lentzeallee 75, 14195, Berlin, Germany.
J Chem Ecol. 2011 Jan;37(1):85-97. doi: 10.1007/s10886-010-9899-7. Epub 2010 Dec 23.
The chrysomelid beetle Phyllotreta striolata is an important pest of Brassicaceae in Southeast Asia and North America. Here, we identified the aggregation pheromone of a population of P. striolata from Taiwan, and host plant volatiles that interact with the pheromone. Volatiles emitted by feeding male P. striolata attracted males and females in the field. Headspace volatile analyses revealed that six sesquiterpenes were emitted specifically by feeding males. Only one of these, however, elicited an electrophysiological response from antennae of both sexes. A number of host plant volatiles, e.g., 1-hexanol, (Z)-3-hexen-1-ol, and the glucosinolate hydrolysis products allyl isothiocyanate (AITC), 3-butenyl isothiocyanate, and 4-pentenyl isothiocyanate also elicited clear responses from the antenna. The active male-specific compound was identified as (+)-(6R,7S)-himachala-9,11-diene by chiral stationary phase gas-chromatography with coupled mass spectrometry, and by comparison with reference samples from Abies nordmanniana, which is known to produce the corresponding enantiomer. The pheromone compound was synthesized starting from (-)-α-himachalene isolated from Cedrus atlantica. Under field conditions, the activity of the synthetic pheromone required concomitant presence of the host plant volatile allyl isothiocyanate. However, both synthetic (+)-(6R,7S)-himachala-9,11-diene alone and in combination with AITC were attractive in a two-choice laboratory assay devoid of other natural olfactory stimuli. We hypothesize that P. striolata adults respond to the pheromone only if specific host volatiles are present. In the same laboratory set up, more beetles were attracted by feeding males than by the synthetic stimuli. Thus, further research will be necessary to reveal the components of a more complex blend of host or male-produced semiochemicals that might enhance trap attractiveness in the field.
皱胫叶甲 Phyllotreta striolata 是东南亚和北美的十字花科植物的重要害虫。在这里，我们鉴定了来自中国台湾的皱胫叶甲种群的聚集信息素，以及与信息素相互作用的寄主植物挥发物。取食雄性皱胫叶甲释放的挥发物在野外吸引了雄性和雌性个体。顶空挥发物分析表明，取食雄性皱胫叶甲特异性地释放了六种倍半萜。然而，只有一种倍半萜能引起两性触角的电生理反应。许多寄主植物挥发物，例如 1-己醇、（Z）-3-己烯-1-醇以及硫代葡萄糖苷水解产物丙烯基异硫氰酸酯（AITC）、3-丁烯基异硫氰酸酯和 4-戊烯基异硫氰酸酯，也能引起触角的明显反应。通过手性固定相气相色谱与质谱联用，以及与已知产生相应对映体的挪威云杉 Abies nordmanniana 的参考样品进行比较，确定具有活性的雄性特异性化合物为 (+)-(6R,7S)-himachala-9,11-二烯。从 Cedrus atlantica 中分离出的（-）-α-himachalene 开始合成该信息素化合物。在野外条件下，合成信息素的活性需要同时存在寄主植物挥发物丙烯基异硫氰酸酯。然而，单独使用合成的 (+)-(6R,7S)-himachala-9,11-二烯以及与 AITC 组合在没有其他天然嗅觉刺激的双选择实验室测定中都具有吸引力。我们假设，只有在存在特定的寄主挥发物的情况下，皱胫叶甲成虫才会对信息素产生反应。在相同的实验室设置中，取食雄性个体比合成刺激物吸引了更多的甲虫。因此，需要进一步的研究来揭示可能增强野外陷阱吸引力的更复杂的寄主或雄性产生的半化学物质混合物的成分。
