The influence of diet on the honeybee lipidome

驯化蜜蜂可以说是世界上最重要的传粉者。每年有数百万商业化管理的蜂群为蔬菜、软果、坚果和油籽作物授粉，确保人类粮食安全。蜜蜂还通过蜂蜜、蜡和其他产品（如皇家浆）为人类福利做出重要的经济贡献。在过去的15-20年里，对蜂群的集约化管理使它们更容易受到病原体和寄生虫全球传播的影响。在某些环境中，蜜蜂暴露在一系列惊人的农业化学品中，包括杀虫剂、杀真菌剂和除草剂。景观管理的变化减少了世界各地开花植物的多样性和丰富性，同时也影响了蜜蜂的食物。为了克服这些短缺，养蜂人现在经常用营养不平衡的人工花粉替代品喂养蜜蜂，使蜜蜂容易患痢疾等疾病。所有这些因素每年都导致蜜蜂集中管理地区的蜂群严重损失。营养在动物健康和福利中起着至关重要的作用。蜜蜂的主要营养来源是花粉和花蜜。花蜜提供碳水化合物，而花粉提供蛋白质，脂肪和微量营养素。许多关于蜜蜂营养的研究都集中在蛋白质的重要性上，但很少有人研究脂肪的作用。脂质是细胞膜的重要组成部分，但也用作信号分子和能量储存。动物可以从碳水化合物中重新合成脂质，但有些脂质必须从饮食中获得。这些脂质包括必需脂肪酸，如多不饱和脂肪酸亚油酸和α-亚麻酸。与哺乳动物不同，昆虫也需要固醇的饮食来源。我们团队的一项重要发现表明，花粉中发现的必需脂肪酸直接影响成年工蜂的营养和行为。含有不正确数量的α-亚麻酸（所谓的“omega-3”）的蜜蜂表现出较差的学习能力。这种饮食引起的行为变化可能会对蜂群产生严重影响，因为觅食蜜蜂必须学习花的特性来获取花粉和花蜜。这里提出的研究准备在蜜蜂群体中的脂质作用方面做出重要发现。我们计划研究哺乳期工蜂如何摄取花粉和蜂粮中的天然脂质，并将其转化为腺分泌物（如皇家浆）喂给幼虫。我们将量化这些脂质是如何分布在成年和幼虫蜜蜂的组织。使用我们实验室开发的先进方法和最先进的脂质组学分析方法，我们将绘制膳食脂肪酸和甾醇转化为脂肪化合物的地图，这些脂肪化合物存在于蜜蜂的内脏、大脑、生殖器官、脂肪体和育雏食物腺中。我们的研究还将确定饮食中的脂肪如何影响幼虫食物的质量，以及饮食引起的幼虫食物中脂肪的变化是否影响发育。我们的最终目标将是测试饮食脂肪如何影响觅食者的寿命和整个殖民地的性能在现场设置。有了这些数据，我们将建议养蜂业使用脂肪替代花粉的最佳实践。利用这些数据，土地管理者还可以选择在花粉中提供正确脂肪酸和甾醇的植物，用于农业生态系统中的花带种植。基于这些原因，我们的研究将有助于提高家养蜜蜂的福利。它有可能通过对授粉服务的影响，为加强全球粮食安全作出重大贡献。

Domesticated honeybees are arguably the most important pollinators in the world. Millions of commercially-managed honeybee colonies pollinate vegetables, soft fruit, nuts and oilseed crops every year, ensuring human food security. Honeybees also make important economic contributions to human welfare through honey, wax, and other products such as royal jelly. In the past 15-20 years, intensive management of honeybee colonies has made them more vulnerable to the global spread of pathogens and parasites. In some settings, bees are exposed to a staggering array of agricultural chemicals including pesticides, fungicides and herbicides. Changes to landscape management have reduced the diversity and abundance of flowering plants throughout the world, with concomitant effects on the food available for bees. To overcome these shortages, beekeepers now routinely feed artificial pollen substitutes with unbalanced nutrition that makes bees susceptible to diseases like dysentery. All of these factors are leading to severe colony losses each year in areas where bees are intensively managed. Nutrition plays a critical role in animal health and welfare. The main source of nutrition of honeybees is floral pollen and nectar. Nectar provides carbohydrates whereas pollen provides protein, fat, and micronutrients. Many studies of bee nutrition have focused on the importance of protein, but few have examined the role of fat. Lipids are important components of cell membranes but are also used as signalling molecules and for energy storage. Animals can synthesize lipids de novo from carbohydrates, but some lipids must be acquired from diet. These lipids include essential fatty acids such as the polyunsaturated fatty acids linoleic and alpha-linolenic acid. Insects, unlike mammals, also require a dietary source of sterols. An important discovery from our team identified that the essential fatty acids found in pollen directly impact the nutrition and behaviour of adult worker honeybees. Bees with the incorrect amount of alpha-linolenic acid (so called 'omega-3') exhibit poor learning abilities. Such diet-induced changes to behaviour could have a serious impact on a bee colony, because foraging bees must learn floral traits to acquire pollen and nectar. The research proposed here is poised to make important discoveries regarding the role of lipids in a honeybee colony. We plan to investigate how natural lipids in the pollen and bee bread consumed by nursing-age worker honeybees are taken up and converted into glandular secretions (e.g. royal jelly) fed to larvae. We will quantify how these lipids are distributed within the tissues of adult and larval bees. Using advanced methods developed in our laboratories and state-of-the-art methods for lipidomic analysis, we will map the transformation of dietary fatty acids and sterols into fat compounds found in bee guts, brains, reproductive organs, fat bodies, and brood food glands. Our research will also identify how fats in diet influence the quality of food given to larvae, and whether diet-induced alterations to fat in larval food affect development. Our ultimate goal will be to test how dietary fats influence the longevity of foragers and whole colony performance in a field setting. With these data, we will advise the beekeeping industry of best practice for the use of fats in substitutes for pollen. Using these data, land managers can also choose plants that provide the correct fatty acid and sterols in pollen for flower strip planting in agroecosystems. For these reasons, our research will lead to the improvement of welfare of domesticated bees. It has the potential to make a significant contribution to the enhancement of global food security through its impact on pollination services.