The macronutrient regulation of adult worker honeybees

世界农业依靠昆虫为开花作物授粉，特别是软水果、蔬菜和坚果作物，这些作物正日益成为大多数人类饮食的基础。随着我们的饮食从谷物和谷物转向更多的蔬菜和水果，对这些服务的需求继续与世界人口同步增长。事实上，人类对需要授粉的水果、坚果和蔬菜的消费量在过去50年里增长了300%。此外，其他授粉后能提高结实率的作物，如油菜，对食物很重要，但也是潜在的生物燃料。传粉者和他们的福祉对我们未来的健康和生存非常重要。驯化蜜蜂是世界农业中最重要的传粉者。商业蜜蜂饲养员维护着数千个蜂群，将它们运送到果园或其他农业场地进行授粉服务。商业养蜂人经常很难找到足够的花粉来喂养他们的蜂群，特别是在一年中天然饲料稀缺的时候。营养不足是蜜蜂群体健康状况不佳的主要因素之一，这些蜜蜂群体饱受病原体和寄生虫的困扰，并暴露在各种农业杀虫剂之下。在过去的20年里，养蜂人开始依赖商业花粉替代品喂养蜂群，但这些替代品没有科学的配方，也没有蜜蜂所需的所有必要营养。我们最近由BBSRC资助的研究调查了成年工蜂的营养需求。我们发现，成年工蜂自行选择蛋白质和碳水化合物的比例，它们对蛋白质和碳水化合物的需求随着种姓的变化而变化。此外，富含蛋白质或必需氨基酸的食物会降低存活率。我们还发现，膳食中必需氨基酸的比例影响蛋白质摄入量的调节。我们最近的工作表明，脂肪含量过高的饮食会缩短成年工蜂的寿命，食物中必需脂肪酸的比例会影响成年工蜂的学习表现和腺体发育。在这里，我们建议扩大我们对蜜蜂营养的研究，以确定蜜蜂是如何调节其蛋白质、脂肪和类固醇的。我们的实验还将研究蛋白质、脂肪和甾醇的来源如何组合，以产生满足蜜蜂对基本营养的需求的混合物。我们将首先测试几种潜在蛋白质来源的消化率，以及它们对成年工蜂食物摄入量的影响。扩展我们之前的研究，我们将测试饮食蛋白质中必需氨基酸的比例如何影响蜜蜂摄入的蛋白质总量。脂肪是蜜蜂的重要营养物质，占蜂王浆干重的近30%(即喂给幼虫和蜂王的腺体分泌物)，但仅占花粉干重的5%-7%。在我们提议的实验中，我们将确定成年工蜂在有和没有幼蜂的情况下所需的蛋白质和脂肪的相对比例。蜜蜂还需要一种在花粉中发现的植物甾醇的饮食来源。我们还将进行实验，测试成年工蜂成功孵化所需的这些类固醇的含量。我们的实验将最终测试整个蜂群中蛋白质、脂肪、碳水化合物和甾醇的组合，并与喂食天然花粉的蜜蜂的表现进行比较。有了这些信息，我们将能够向养蜂人提供建议，在没有花粉的情况下，可以使用哪些材料及其组合来配制花粉的替代品。

World agriculture relies on insects to pollinate flowering crops, especially soft fruit, vegetable, and nut crops, that are increasingly forming the basis of most human diets. As our diet shifts from grains and cereals to including more vegetables and fruits, the demand for these services continues to grow in step with the world's population. In fact, human consumption of fruits, nuts and vegetables that require pollination has increased as much as 300% in the past 50 years. In addition, other crops that improve seed set when pollinated such as oilseed rape are important for food but are also potential biofuels. Pollinators, and their well-being, are important to our future health and survival. Domesticated bees are the most important pollinators used in world agriculture. Commercial honeybee keepers maintain thousands of colonies, transporting them to orchards or other agricultural field settings to perform pollination services. Commercial beekeepers often struggle to find enough pollen to feed their colonies, especially at times of year when natural forage is scarce. Insufficient nutrition is one of the main factors for the poor health in honeybee colonies that are beset by pathogens and parasites, as well as exposed to a diversity of agricultural pesticides. In the past 20 years, beekeepers have started to rely on feeding colonies with commercial pollen substitutes but these substitutes are not scientifically formulated and do not have all of the essential nutrients bees need.Our recent BBSRC-funded research investigated the adult worker honeybee's nutritional needs. We found that adult worker bees self-select proportions of protein and carbohydrate and that their demands for protein and carbohydrate change as a function of their caste. In addition, foods high in protein or essential amino acids reduce survival. We also found that the proportion of essential amino acids in diet affected the regulation of protein intake. Our recent work indicates that diets too high in fat shorten adult worker bee lifespan, and that the proportions of essential fatty acids in food affect learning performance and glandular development in adult worker honeybees. Here, we propose to extend our research on bee nutrition to identify how bees regulate their protein, fat, and sterols. Our experiments will also examine how sources of proteins, fats, and sterols can be combined to produce mixtures that meet the honeybee's needs for essential nutrients. We will start by testing the digestibility of several potential protein sources and their effect on the intake of food in adult worker bees. Extending our previous research, we will test how the proportion of essential amino acids in dietary protein affects the total amount of protein bees consume. Fat is an important nutrient for bees, and makes up nearly 30% of the dry weight of royal jelly (i.e. glandular secretions fed to larvae and the queen) but is only found at between 5-7% of the dry weight of pollen. In our proposed experiments, we will identify the relative ratio of protein to fat needed by adult worker bees in the presence and absence of brood. Bees also need a dietary source of phytosterols that are found in pollen. We will also perform experiments that test how much of these sterols adult worker bees need to rear brood successfully. Our experiments will lead to a final test of a combination of protein, fat, carbohydrate, and sterols in whole colonies compared to the performance of bees fed with natural pollen. With this information, we will be able to provide advice to beekeepers on the materials and their combinations that can be used to formulate substitutes for pollen when pollen is unavailable.