An experimental evaluation of traits that influence the sexual behaviour of pollinators in sexually deceptive orchids

Pollination by sexual deception of male insects is perhaps one of the most remarkable cases of mimicry in the plant kingdom. However, understanding the influence of floral traits on pollinator behaviour in sexually deceptive orchids is challenging, due to the risk of confounding changes in floral odour when manipulating morphology. Here, we investigated the floral traits influencing the sexual response of male Zaspilothynnus nigripes (Tiphiidae) wasps, a pollinator of two distantly related sexually deceptive orchids with contrasting floral architecture, Caladenia pectinata and Drakaea livida. In D. livida the chemical sexual attractant is emitted from the labellum, while in C. pectinata it is produced from the distal sepal tips, allowing manipulative experiments. When controlling for visual cues there was no difference in long distance attraction, though the floral odour of D. livida induced copulation more frequently than that of C. pectinata. The role of colour in pollinator sexual at...利用性欺骗（sexual deception）手段吸引雄性昆虫完成传粉，或许是植物界最引人注目的拟态（mimicry）现象之一。然而，在性欺骗兰科植物（sexually deceptive orchids）中，解析花部性状（floral traits）对传粉者行为（pollinator behaviour）的影响颇具挑战——这是因为在操控植株形态结构时，极易引发花部气味的混淆性变化，进而干扰实验结果。本研究针对雄性黑带臀蜂（Zaspilothynnus nigripes，臀蜂科（Tiphiidae））的性反应相关花部性状展开探究。该蜂是两种远缘亲缘、花部结构迥异的性欺骗兰科植物Caladenia pectinata与Drakaea livida的传粉者。在Drakaea livida中，化学性引诱剂由唇瓣（labellum）释放；而在Caladenia pectinata中，该引诱剂则产自萼片远端尖端，这为操控性实验的开展提供了条件。当控制视觉信号变量后，两种兰花的远距离吸引效果并无显著差异，但Drakaea livida的花部气味诱导雄性蜂交配的频率显著高于Caladenia pectinata。颜色在传粉者性吸引中的作用……