Data from: Bees eavesdrop upon informative and persistent signal compounds in alarm pheromones

Pollinators such as bees provide a critical ecosystem service that can be impaired by information about predation. We provide the first evidence for olfactory eavesdropping and avoidance of heterospecific alarm signals, alarm pheromones, at food sources in bees. We predicted that foragers would eavesdrop upon heterospecific alarm pheromones, and would detect and avoid conspicuous individual pheromone compounds, defined by abundance and how long they can linger to provide warning information (volatility). We show that Apis cerana foragers avoid the distinctive alarm pheromones of A. dorsata and A. mellifera, species that share the same floral resources and predators. We next examined responses to individual alarm pheromone compounds. Apis cerana foragers avoided isopentyl acetate (IPA), which is found in all three species and is the most abundant and volatile of the tested compounds. Interestingly, A. cerana also avoided two odor components, gamma-octanoic lactone (GOL) and (E)-2-decen-1-yl-acetate (DA), which are only present in A. dorsata alarm pheromone and are >150-fold less volatile than IPA. Neural recordings (EAG) revealed that A. cerana antennae are 10-fold more sensitive to GOL and DA than to other tested compounds. Thus, the eavesdropping strategy is shaped by signal conspicuousness (abundance and commonality) and signal persistence (volatility).传粉者如蜂类可提供关键的生态系统服务，而捕食相关信息会干扰这一服务的正常发挥。我们首次证实了蜂类在觅食场所能够通过嗅觉窃听并规避异种告警信号——即告警信息素（alarm pheromones）。我们曾提出假说：觅食蜂会窃听异种告警信息素，并能识别并规避那些因含量高、挥发持久（即挥发性）而具备显著告警特性的单一信息素组分。实验结果显示，东方蜜蜂（Apis cerana）的觅食蜂会规避大蜜蜂（Apis dorsata）与西方蜜蜂（Apis mellifera）的特异性告警信息素；这两类蜂与东方蜜蜂共享相同的蜜源资源与捕食者类群。随后我们针对单一告警信息素组分展开了响应实验。东方蜜蜂的觅食蜂会规避乙酸异戊酯（isopentyl acetate, IPA），该组分存在于上述三个蜂种中，也是本次测试的所有组分中含量最高且挥发性最强的物质。值得注意的是，东方蜜蜂还会规避两种气味组分：γ-辛酸内酯（gamma-octanoic lactone, GOL）与(E)-2-癸烯-1-基乙酸酯（(E)-2-decen-1-yl-acetate, DA），这两种组分仅存在于大蜜蜂的告警信息素中，且其挥发性仅为IPA的1/150以上。触角电位（electroantennography, EAG）记录结果显示，东方蜜蜂的触角对GOL与DA的敏感度是其他测试组分的10倍。综上，蜂类的嗅觉窃听策略由信号显著性（含量与分布普遍性）以及信号持久性（挥发性）共同塑造。