Chemistry Research Unit, Center for Medical, Agricultural and Veterinary Entomology, Agricultural Research Service, United States Department of Agriculture, Gainesville, FL, 32608, USA.
Department of Entomology and Nematology, University of California Davis, Davis, CA, 95616, USA.
J Chem Ecol. 2020 Aug;46(8):659-667. doi: 10.1007/s10886-020-01169-3. Epub 2020 Apr 3.
Microbial metabolism can shape cues important for animal attraction in service-resource mutualisms. Resources are frequently colonized by microbial communities, but experimental assessment of animal-microbial interactions often focus on microbial monocultures. Such an approach likely fails to predict effects of microbial assemblages, as microbe-microbe interactions may affect in a non-additive manner microbial metabolism and resulting chemosensory cues. Here, we compared effects of microbial mono- and cocultures on growth of constituent microbes, volatile metabolite production, sugar catabolism, and effects on pollinator foraging across two nectar environments that differed in sugar concentration. Growth in co-culture decreased the abundance of the yeast Metschnikowia reukaufii, but not the bacterium Asaia astilbes. Volatile emissions differed significantly between microbial treatments and with nectar concentration, while sugar concentration was relatively similar among mono- and cocultures. Coculture volatile emission closely resembled an additive combination of monoculture volatiles. Despite differences in microbial growth and chemosensory cues, honey bee feeding did not differ between microbial monocultures and assemblages. Taken together, our results suggest that in some cases, chemical and ecological effects of microbial assemblages are largely predictable from those of component species, but caution that more work is necessary to predict under what circumstances non-additive effects are important.
微生物代谢可以塑造动物吸引力的关键线索，这些线索在服务资源互惠关系中很重要。资源经常被微生物群落占据，但动物与微生物相互作用的实验评估通常集中在微生物单培养物上。这种方法可能无法预测微生物组合的影响，因为微生物之间的相互作用可能会以非加性的方式影响微生物代谢和产生的化学感觉线索。在这里，我们比较了微生物单培养物和共培养物对组成微生物生长、挥发性代谢产物产生、糖代谢以及对两种糖浓度不同的花蜜环境中传粉者觅食的影响。共培养中微生物的生长减少了酵母 Metschnikowia reukaufii 的丰度，但对细菌 Asaia astilbes 没有影响。挥发性排放物在微生物处理之间以及与花蜜浓度之间存在显著差异，而单培养物和共培养物之间的糖浓度相对相似。共培养物的挥发性排放物与单培养物挥发性物质的加和组合非常相似。尽管微生物生长和化学感觉线索存在差异，但蜜蜂的取食在微生物单培养物和组合之间没有差异。总的来说，我们的结果表明，在某些情况下，微生物组合的化学和生态效应在很大程度上可以从组成物种的效应来预测，但需要注意的是，需要做更多的工作来预测在什么情况下非加性效应是重要的。
