Rering Caitlin C, Rudolph Arthur B, Beck John J
Chemistry Research Unit, Center for Medical, Agricultural and Veterinary Entomology, Agricultural Research Service, United States Department of Agriculture, Gainesville, FL, 32608, USA.
Environ Microbiol. 2021 Aug;23(8):4141-4150. doi: 10.1111/1462-2920.15528. Epub 2021 Apr 25.
Floral nectar often contains pollen and microorganisms, which may change nectar's chemical composition, and in turn impact pollinator affinity. However, their individual and combined effects remain understudied. Here, we examined the impacts of the nectar specialist yeast, Metschnikowia reukaufii, and the addition of sunflower (Hellianthus annus) pollen. Pollen grains remained intact, yet still increased yeast growth and amino acid concentrations in nectar, whereas yeast depleted amino acids. Pollen, but not yeast, changed nectar sugar concentrations by converting sucrose to its monomers. Both pollen and yeast contributed emissions from nectar, though yeast volatiles were more abundant than pollen volatiles. Yeast volatile emission was positively correlated with pollen concentration and cell density, and yeast depleted a subset of pollen-derived volatiles. Honey bees avoided foraging on yeast-inoculated nectar and foraged equally among uninoculated nectars regardless of pollen content, underscoring the importance of microbial metabolites in mediating pollinator foraging.
花蜜通常含有花粉和微生物，这可能会改变花蜜的化学成分，进而影响传粉者的喜好。然而，它们各自的以及综合的影响仍未得到充分研究。在这里，我们研究了花蜜专性酵母鲁考夫梅奇酵母（Metschnikowia reukaufii）以及添加向日葵（Helianthus annus）花粉的影响。花粉粒保持完整，但仍增加了酵母的生长以及花蜜中的氨基酸浓度，而酵母消耗了氨基酸。花粉而非酵母通过将蔗糖转化为其单体改变了花蜜的糖浓度。花粉和酵母都促成了花蜜的挥发物排放，不过酵母挥发物比花粉挥发物更为丰富。酵母挥发物排放与花粉浓度和细胞密度呈正相关，并且酵母消耗了一部分源自花粉的挥发物。蜜蜂避免在接种了酵母的花蜜上觅食，并且无论花粉含量如何，在未接种的花蜜中觅食的情况相同，这突出了微生物代谢产物在介导传粉者觅食中的重要性。
