Department of Entomology, Washington State University, Pullman, WA 99164, USA.
Department of Entomology and Nematology, University of California Davis, Davis, CA 95616, USA.
Biol Lett. 2019 Jul 26;15(7):20190132. doi: 10.1098/rsbl.2019.0132. Epub 2019 Jul 17.
Animals such as bumblebees use chemosensory cues to both locate and evaluate essential resources. Increasingly, it is recognized that microbes can alter the quality of foraged resources and produce metabolites that may act as foraging cues. The distinct nature of these chemosensory cues however and their use in animal foraging remain poorly understood. Here, we test the hypothesis that species of nectar-inhabiting microbes differentially influence pollinator attraction and feeding via microbial metabolites produced in nectar. We first examined the electrophysiological potential for bumblebee (Bombus impatiens) antennal olfactory neurons to respond to microbial volatile organic compounds (mVOCs), followed by an olfactory preference test. We also assessed gustatory preferences for microbial-altered nectar through both no-choice and choice feeding assays. Antennal olfactory neurons responded to some mVOCs, and bees preferred nectar solutions inoculated with the bacterium Asaia astilbes over the yeast Metschnikowia reukaufii based on volatiles alone. However, B. impatiens foragers consumed significantly more Metschnikowia-inoculated nectar, suggesting distinct roles for mVOCs and non-volatile metabolites in mediating both attraction and feeding decisions. Collectively, our results suggest that microbial metabolites have significant potential to shape interspecific, plant-pollinator signalling, with consequences for forager learning, economics and floral host reproduction.
动物（如大黄蜂）利用化学感觉线索来定位和评估重要资源。越来越多的人认识到，微生物可以改变觅食资源的质量，并产生可能作为觅食线索的代谢物。然而，这些化学感觉线索的独特性质及其在动物觅食中的应用仍知之甚少。在这里，我们测试了以下假设：花蜜中栖息的微生物物种通过花蜜中产生的微生物代谢物，以不同的方式影响传粉者的吸引力和取食。我们首先检查了大黄蜂（Bombus impatiens）触角嗅觉神经元对微生物挥发性有机化合物（mVOCs）反应的电生理潜力，然后进行了嗅觉偏好测试。我们还通过无选择和选择喂养试验评估了对微生物改变的花蜜的味觉偏好。触角嗅觉神经元对一些 mVOCs 有反应，并且蜜蜂仅根据挥发物更喜欢接种细菌 Asaia astilbes 的花蜜溶液而不是接种酵母 Metschnikowia reukaufii 的溶液。然而，B. impatiens 觅食者消耗的 Metschnikowia 接种花蜜明显更多，这表明 mVOCs 和非挥发性代谢物在介导吸引力和取食决策方面具有不同的作用。总的来说，我们的结果表明，微生物代谢物具有显著的潜力来塑造种间、植物-传粉者信号传递，对觅食者的学习、经济和花卉宿主的繁殖都有影响。
