Intraspecific variation of floral signals, and particularly floral scent, is widespread in orchid species. Pollinator-mediated selection is often hypothesized to govern such polymorphism. For example, circadian rhythms of floral emissions have been associated to the daily activity patterns of pollinators in several plant species. However, most of the studies on floral scent variation usually consider only one factor of variation (diel variation, pollination, flower age …). In this study, we investigated simultaneously seven sources of variation susceptible to induce changes in floral scent emissions in the food-deceptive orchid Orchis mascula: circadian rhythm, flower age, pollination, inflorescence morphology, herbivory, leaf spots and habitat. We found that all the factors studied, except plant morphology (spots on leaves, inflorescence morphology), were associated with significant changes in the volatile profile of O. mascula inflorescences. Electroantennography experiments with Bombus terrestris, the main pollinator of O. mascula, revealed that bumblebees were able to detect almost all the compounds involved in floral scent variation. Whether pollinator behaviour is influenced by changes in floral odours induced by these different factors, and whether it can affect plant reproductive success will have to be tested in further studies.

花卉信号，特别是花香的种内变异在兰花物种中很普遍。通常假设授粉媒介介导的选择可控制这种多态性。例如，花卉排放的昼夜节律与几种植物物种中授粉媒介的日常活动模式有关。但是，大多数关于花香变化的研究通常仅考虑变化的一个因素（迪尔变化，授粉，花龄……）。在这项研究中，我们同时调查了易受诱食兰花的兰花Orchis mascula中七种变异源的影响，这些变异易于诱发花香释放的变化。：昼夜节律，花龄，授粉，花序形态，食草，叶斑和栖息地。我们发现，除植物形态（叶片上的斑点，花序形态）外，所有研究的因素均与O. mascula花序挥发性分布的显着变化有关。用熊蜂的主要传粉者-熊蜂（Bombus terrestris）进行的脑电图实验表明，大黄蜂能够检测到几乎所有与花香变化有关的化合物。传粉媒介的行为是否受这些不同因素引起的花香变化的影响，以及是否会影响植物的繁殖成功，将有待进一步研究。