Mass-flowering crops: cost or benefit to bumblebees and wild flower pollination?

人们普遍认为，传粉者正在减少，这对自然植物群落和农业生产力都构成了威胁。尽管这种下降最近受到了质疑，但大多数当局都认为，一些重要的传粉者群体，特别是大黄蜂，在欧洲的数量和范围都有所下降。在英国，许多植物物种的丰度也有很好的记录，特别是多年生草本植物，如黄花草属和红三叶草。英国大量开花的作物(主要是油菜和菜豆)的种植可以说是几个世纪以来花卉景观最戏剧性的变化。申请者最近的研究表明，当开花时，这些作物提供的花粉和花蜜的数量远远超过所有其他受昆虫访问的开花植物在可耕作景观中提供的总和。然而，对于这种短暂的花卉资源过剩对传粉者种群或野花繁殖的影响，我们仍然知之甚少。对于大量开花的作物是否有利于大黄蜂的种群，人们存在分歧(它们提供了大量资源，但种群的成功需要整个春夏持续的食物供应，一些蜜蜂物种避免开浅的花，如油菜)。大量开花的作物也可能影响授粉，从而在可耕种的生态系统的野花中结籽。但目前尚不清楚野花是否会因为与这种作物争夺传粉者，或者因为这种作物的花粉堵塞柱头而受到不利影响，或者相反，它们是否会从当地传粉者数量的增加中受益。答案将取决于作物和野花的物候和花的相似性。野生花卉种群过程及其传粉者在农田中的种群动态从来没有被放在一个单一的项目中考虑。该项目旨在利用BBSRC以前资助的申请者的工作，通过三管齐下的方法，评估大量开花作物的数量和景观规模的空间分布如何影响传粉者种群(特别是熊蜂)和野花的繁殖：a.研究油菜和田豆对大黄蜂群体生存的影响，重点关注两个截然不同的蜜蜂物种，长舌头的B.pascuorum和短舌头的B.lapidarius。申请者首创的分子方法将被用来在整个季节(Goulson@Stirling)探测巢穴。B.研究这些大开花作物对传粉者访问和在五个目标野花物种中结实的影响，选择提供一系列物候和花朵形态(Osborne@Rothamsted)ci)扩展、开发和测试现有的基于地理信息系统的饲草地图和相关模型，以预测可耕种景观中牧草的分布和物候如何决定传粉者的丰度，特别是哪些地区充当熊蜂的汇区，哪些地区充当来源(蜂王的净出口国)(Sanderson@NewCastle)CII)使用相同的饲草地图来开发新的空间清晰的模型，以检查更广泛的，大规模开花作物对传粉者访问和在野花种群中结实的景观尺度效应结合在一起，这项工作将使我们能够评估种植大规模开花作物对传粉者和野花的可能生态后果，并将大大提高我们预测和操纵农业实践对农田生物多样性影响的能力。该项目与制定耕地和农村管理计划的政策制定者有直接关系，例如那些为田地边际管理提供建议的人。鼓励大量大黄蜂种群的做法反过来将促进农作物和野生植物的授粉，支持非耕种农田上多样化植物区系的可持续性。

There is a widespread perception that pollinators are in decline, and that this threatens both natural plant communities and agricultural productivity. Although this decline has recently been questioned, most authorities agree that some important pollinator groups, notably bumblebees, have declined in both abundance and range in Europe. There are also well documented declines in abundance of many plant species in the UK, particularly perennial herbs such as cowslips and red clover. The cultivation of mass-flowering crops (primarily oilseed rape and field beans) in the UK has been arguably the most dramatic change to the floral landscape for centuries. Recent work by the applicants shows that, when in bloom, the amount of pollen and nectar provided by these crops greatly exceeds that provided by all other insect-visited flowering plants combined in arable landscapes. We still have a poor understanding, however, of the impact that this brief glut of floral resources has on pollinator populations or on the reproduction of wildflowers. There is disagreement as to whether mass-flowering crops are of benefit to populations of bumblebees (they provide a lot of resources, but colony success requires a continuous supply of food throughout spring and summer, and some bee species avoid shallow flowers like oilseed rape). Mass-flowering crops are also likely to affect pollination and hence seed set in wildflowers of arable ecosystems. But it is unclear whether wildflowers will suffer adverse affects from competition with the crop for pollinators or through stigma-clogging with pollen from such crops, or conversely whether they will benefit from a boost to local pollinator populations. The answer will depend on the phenology and floral similarity of crop and wildflower. Wild flower population processes and their pollinators' population dynamics in farmland have never been considered together in a single project. This project aims to capitalise on previous BBSRC-funded work by the applicants, to assess how the amount and landscape-scale spatial distribution of mass-flowering crops affect pollinator populations (particularly bumblebees) and reproduction of wildflowers, using a three-pronged approach: A. Studies of the effects of oilseed rape and field beans on bumblebee colony survival, focussing on two contrasting bee species, the longer tongued B. pascuorum and the shorter-tongued B. lapidarius. Molecular approaches pioneered by the applicants will be used to detect nests through the season (Goulson@Stirling). B. Studies of the effects of these same mass-flowering crops on pollinator visitation and seed-set in five target wildflower species, chosen to provide a range of phenologies and flower morphologies (Osborne@Rothamsted) Ci) Expansion, development and testing of an existing GIS-based forage map and associated model to predict how the distribution and phenology of forage in arable landscapes determines pollinator abundance, and in particular which areas act as sinks for bumblebees, and which act as sources (net exporters of queens) (Sanderson@Newcastle) Cii) Use of the same forage map to develop new spatially-articulate models to examine the broader, landscape scale effects of mass-flowering crops on pollinator visitation to, and seed set in, wildflower populations In combination, this work will enable us to evaluate the likely ecological consequences of growing mass-flowering crops on pollinators and wildflowers, and will substantially increase our ability to predict and manipulate the impacts of agricultural practices on farmland biodiversity. The project is of direct relevance to policy makers producing schemes for arable and countryside stewardship, for example those advising on field margin management. Practices that encourage large bumblebee populations will in turn boost pollination of crops and wild plants, underpinning the sustainability of a diverse flora on unfarmed agricultural land.