Fine-tuned floral filters in melittophilous flowers sort out particular bees

蜜蜂被认为是可靠的传粉者;这是由蜜蜂的访花频率和它们的花的恒定性所证实的，但蜜蜂收集花粉用于幼虫食物供应是一个挑战。已被梳理成花粉运输结构的花粉粒不再可用于授粉。这种花粉分配的目的，而不是授粉相当于一个两难的蜜蜂授粉开花植物。在这个项目中，我们将调查三个迄今为止未研究的和连贯的方面，这种花粉困境，通过测试是否以及如何花操纵蜜蜂优化花粉转移。1.花粉粒的刺参与花粉粒被蜜蜂收集的机械防御。我们将测试刺数，刺长度，花粉粒直径，花粉水合作用和添加的脱水花蜜的作用，以了解多刺的花粉是防御收集由corbiculate蜜蜂的机制。此外，我们将测试开花植物是否使用多刺的花粉粒来限制蜜蜂采集花蜜，因为采集花蜜的蜜蜂不太频繁地梳理自己。2.在蜜蜂身体的安全部位上的花粉粒经历较小的概率被梳理到花粉运输结构中，从那里它们不能为花授粉。我们将测试龙骨花是否代表一个例外，并可以使用scopa作为一种安全的网站授粉蜜蜂。我们将测试是否龙骨花的刚度，这只能由megachilid蜜蜂打开，代表花的适应，以促进花粉粒从蜜蜂的腹侧scopa的柱头的花。这将是第一个证据授粉的肥沃的scopal花粉，并构成强大的选择压力，各自的花排除蜜蜂不具备腹侧scopa。3.许多蜜蜂授粉的花具有花粉和雄蕊模仿结构，被认为是视觉花卉指南。我们将研究尚未探索的功能，花粉和雄蕊模仿结构触发梳理行为的蜜蜂通过触觉刺激。我们将测试的假设，雄蕊模仿结构设置一个更强的触发梳理比真实的雄蕊。此外，我们将测试，如果喂养雄蕊诱导梳理更强烈比授粉雄蕊在异花药花。这些实验将表明，如果花能够操纵蜜蜂梳理触觉线索，以促进花粉转移到同种花。这些研究的连贯方面是微调花过滤器，蜜蜂授粉的花朵可能能够排除不同的蜜蜂，从而提高授粉成功。这些研究将集中在目前未充分研究的访花蜜蜂和喜蜜开花植物之间的互惠互利的拮抗方面。

Bees are considered reliable pollinators; this is corroborated by the bees frequency of flower visits and their flower constancy, but challenged by the bees collection of pollen for larval food provisioning. Pollen grains which have been groomed into the pollen transport structures are no longer available for pollination. This allocation of pollen for a purpose other than pollination amounts to a dilemma for bee-pollinated flowering plants. In this project we will investigate three so far unstudied and coherent aspects of this pollen dilemma by testing whether and how flowers manipulate bees for optimization of pollen transfer. 1. Spines of pollen grains are involved in the mechanical defence of pollen grains from being collected by corbiculate bees. We will test the role of spine number, spine length, pollen grain diameter, pollen hydration and added regurgitated nectar in order to understand the mechanism by which spiny pollen is defended against collection by corbiculate bees. In addition we will test if flowering plants use spiny pollen grains to restrict bees to nectar collection, because nectar collecting bees groom themselves less frequently. 2. Pollen grains on safe sites of bees bodies experience a smaller probability of being groomed into the pollen transport structures, from where they cannot pollinate flowers. We will test whether keel blossoms represent an exception and can use the scopa as a kind of safe site of pollinating bees. We will test whether the stiffness of keel flowers, which can only be opened by megachilid bees, represents a floral adaptation to promote transfer of pollen grains from the ventral scopa of the bee to stigma of the flower. This would be the first evidence for pollination by fertile scopal pollen and constitute strong selective pressure for the respective flowers to exclude bees that do not possess a ventral scopa. 3. Many bee-pollinated flowers possess pollen- and stamen-mimicking structures which are considered to function as visual floral guides. We will study the as yet unexplored function of pollen- and stamen-mimicking structures to trigger grooming behaviour in bees by means of tactile stimuli. We will test the hypothesis that stamen-mimicking structures set a stronger trigger for grooming than real stamens. In addition we will test if feeding stamens induce grooming more strongly than pollination stamens in heterantherous flowers. These experiments will show if flowers are able to manipulate the bees grooming by tactile cues in order to promote pollen transfer to conspecific flowers. The coherent aspect of these studies is the fine-tuned floral filter by which bee-pollinated flowers might be able to exclude distinct bees and thereby improve pollination success. These studies will focus on currently understudied antagonistic aspects of the mutualism between flower-visiting bees and melittophilous flowering plants.