BACKGROUND Significant annual honey bee colony losses have been reported in the USA and across the world over the past years. Malnutrition is one among several causative factors for such declines. Optimal nutrition serves as the first line of defense against multiple stressors such as parasites/pathogens and pesticides. Given the importance of nutrition, it is imperative to understand bee nutrition holistically, identifying dietary sources that may fulfill bee nutritional needs. Pollen is the primary source of protein for bees and is critical for brood rearing and colony growth. Currently, there is significant gap in knowledge regarding the chemical and nutritional composition of pollen. METHODS Targeted sterol analysis and untargeted metabolomics were conducted on five commercially available crop pollens, three bee-collected crop pollens, three vegetable oils (often added to artificial protein supplements by beekeepers), and one commonly used artificial protein supplement. RESULTS This study reports key phytosterols and metabolites present across a spectrum of bee diets, including some of the major bee-pollinated crop pollens in the western United States. Significant differences were observed in sterol concentrations among the dietary sources tested. Among all quantified sterols, the highest concentrations were observed for 24-methylenecholesterol and further, pollen samples exhibited the highest 24-methylenecholesterol among all diet sources that were tested. Also, 236 metabolites were identified across all dietary sources examined. CONCLUSION Information gleaned from this study is crucial in understanding the nutritional landscape available to all bee pollinators and may further assist in future efforts to develop comprehensive database of nutrients and metabolites present in all bee diets.

中文翻译：

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蜜蜂营养景观的组学方法。

背景技术在过去的几年中，在美国和世界各地已经报告了每年严重的蜜蜂群体损失。营养不良是造成这种下降的几种原因之一。最佳营养是抵御多种压力源（例如寄生虫/病原体和农药）的第一道防线。考虑到营养的重要性，必须全面了解蜜蜂的营养，确定可以满足蜜蜂营养需求的饮食来源。花粉是蜜蜂蛋白质的主要来源，对育雏和菌落生长至关重要。目前，关于花粉的化学和营养成分的知识存在很大差距。方法对5种市售农作物花粉，3种蜜蜂采集的农作物花粉进行了靶向固醇分析和非靶向代谢组学研究，三种植物油（养蜂人通常将其添加到人工蛋白补充剂中）和一种常用的人工蛋白补充剂。结果这项研究报告了蜜蜂饮食中存在的主要植物固醇和代谢产物，包括美国西部一些主要的蜜蜂授粉作物花粉。在所测试的饮食来源中，观察到固醇浓度存在显着差异。在所有定量固醇中，观察到最高浓度的24-亚甲基胆固醇，而且在所有测试的饮食来源中，花粉样品显示出最高的24-亚甲基胆固醇。此外，在所有检查的饮食来源中鉴定出236种代谢物。