Towards 'crop-pollinating' landscapes: quantifying pollen supply and demand to manage wild pollinators for their benefits to food production

世界上四分之三的重要农作物，或按产量计算占所有粮食产量的35%，依赖于动物授粉。这包括许多水果，蔬菜，坚果和油。最近，科学家们发现，世界上大多数农作物授粉是由一小群蜜蜂物种进行的，称为“主导农作物授粉者”。在英国，不超过20个物种正在做大部分的工作。一种是蜜蜂，由养蜂人饲养。其他的都是农田常见的野生品种，但各地野生蜂种的数量都在下降。这种下降的主要原因之一是乡村野花的损失，这在英国世纪是戏剧性的。特别是豌豆和豆类家族中有花植物的损失，这些植物具有富含蛋白质的花粉，被认为给野生蜜蜂物种带来了麻烦。蜜蜂完全依靠花朵的食物-花蜜和花粉-来生存和养育它们的后代。花蜜是一种糖浆，为它们提供飞行和生长的能量。花粉提供了大部分的蛋白质，这是幼虫生长的重要资源。帮助传粉者的一种方法是种植额外的花朵。这已被证明可以增加占主导地位的作物授粉者的数量，甚至可以提高作物产量。目前，科学家们不知道野生蜜蜂在一年中的不同时间需要多少或什么类型的花粉才能生存，也不知道现有景观已经提供了多少花粉。有些人认为一年中有一些特定的时间，比如早春或夏末，花粉特别有限，增加花朵确实会帮助蜜蜂。这项研究使用了非常新的科学技术来量化农田花粉的需求和供应。一个令人兴奋的进展是，科学家们刚刚从所有1,479种英国本土植物中建立了一个DNA序列库。这使得通过将花粉放入测序仪来识别蜜蜂收集的花粉中的植物物种成为可能。这就是所谓的DNA元条码。蜜蜂的早期研究结果表明，树木的花粉在年初可能比以前认为的更重要。这项研究将记录红尾和早期熊蜂群体在至少两年内使用的所有植物。在实验室中对熊蜂进行的一系列实验将测试需要多少和什么样的花粉来饲养个体幼虫，或提供一个健康的群体。将这些信息与它们在真实的景观中选择的花粉来源相结合，将使我能够准确地计算这些为作物授粉的熊蜂的花粉需求。为了量化农田区域的花粉供应，我将使用从细胞生物学中借来的图像处理技术，通过照片测量春、夏、秋三季每种花的数量。他们的想法是建立一个易于使用的软件，告诉农民种植什么样的花，这样他们的农场就能支持一个繁荣的野生传粉者社区，为他们的作物提供可靠的授粉。该软件将每月比较花粉供应和花粉需求。能够测量农田地区的花粉供应和需求将使科学家能够回答一个正在进行的关于传粉者的争论的核心问题：目前是什么限制了野生传粉者的数量？是可用的蛋白质（花粉）的主要限制因素，还是碳水化合物（花蜜），筑巢地点，越冬死亡率或农药或疾病的负面影响？我的研究的总体目标是检验花粉是农业景观中的限制因素的假设。如果是正确的，那么我们能为传粉者做的最好的事情就是种花。如果它是错误的，并且有其他因素限制了传粉者的数量或导致数量下降，那么就需要采取不同的策略来保留支持粮食生产的勤劳的野生传粉者的可行社区。

Three quarters of the world's important crops, or 35% of all food produced by volume, depends on animal pollinators. This includes many fruits, vegetables, nuts and oils. Recently, scientists have found that most crop pollination in the world is carried out by a small group of bee species, called the 'dominant crop pollinators'. In the UK, no more than 20 species are doing most of the work. One is the honey bee, kept by beekeepers. The others are wild species found commonly in farmland.Yet numbers of wild bee species found in each place are declining. One of the main reasons for this decline is loss of wild flowers in the countryside, which was dramatic in the twentieth century in the UK. In particular, the loss of flowering plants in the pea and bean family, which have protein-rich pollen, is thought to have caused trouble for wild bee species. Bees rely entirely on food from flowers - nectar and pollen - to survive and raise their young. Nectar is a sugar syrup, and provides them energy to fly and grow. Pollen provides most of the protein, a crucial resource for growing larvae. One way to help pollinators is by planting extra flowers. This has been shown to increase the numbers of dominant crop pollinators, and can even lead to improvements in crop yield. At the moment scientists don't know how much, or what types of pollen wild bees need to survive at different times of year, and have very little idea how much pollen is already supplied by existing landscapes. Some think there are particular times of year, such as early spring or late summer, when pollen is especially limiting, and adding flowers would really help bees.This research uses very new scientific techniques to quantify the demand for and supply of pollen in farmland. One exciting development is that scientists have just made a library of DNA sequences from all 1,479 of UK native plants. This makes it possible to identify plant species in bee-collected pollen, by putting the pollen into a sequencing machine. It's called DNA metabarcoding. Early results for honey bees show that pollen from trees could be more important at the start of the year than was previously thought. This research will document all the plants that red-tailed and early bumblebee colonies use over at least two years.A series of experiments with bumblebees in the laboratory will test how much and what kind of pollen are needed to raise individual larvae, or supply a healthy colony. Combining this information with the pollen sources they choose in real landscapes will allow me to accurately calculate pollen demand by these crop-pollinating bumblebees.To quantify pollen supply in an area of farmland, I will use image processing techniques borrowed from cell biology to measure how many flowers of each type there are through spring, summer and autumn, using photographs. The idea is to build an easy-to-use piece of software to tell farmers exactly what flowers to plant so their farm supports a thriving wild pollinator community that provides reliable pollination to their crops. The software will compare pollen supply with pollen demand on a monthly basis.Being able to measure pollen supply and demand in an area of farmland will allow scientists to answer a fundamental question central to ongoing debates about pollinators: What currently limits wild pollinator populations? Is available protein (pollen) the main limiting factor, or is it carbohydrate (nectar), nesting sites, overwinter mortality or negative impacts of pesticides or disease? The overall aim of my research is to test the hypothesis that pollen is the limiting factor in agricultural landscapes. If correct, then the best thing we can do for pollinators is plant flowers. If it is wrong, and something else is limiting pollinator numbers or causing declines, then different strategies will be necessary to retain viable communities of hard-working wild pollinators that support food production.