Bean cultivation in diverse agricultural landscapes encourages bees and increases yields

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Eine Hummel raubt Nektar von einer Ackerbohne. Foto: Nicole Beyer

Eine Hummel raubt Nektar von einer Ackerbohne. Foto: Nicole Beyer

Researchers led by the University of Göttingen study bee behaviour and yield development

Pollination by insects is essential for the production of many food crops. The occurrence of pollinators such as bees depends on whether nesting sites and sufficient food are available. If these conditions are lacking, the pollinators also fail to appear and the yield of flowering arable crops such as field beans and rape suffers. A team from the University of Göttingen and the Julius Kühn-Institut (JKI) in Braunschweig has investigated how the landscape composition of flowering crops and near-natural habitats affects the densities of bees, their behaviour when collecting nectar and the yields of field beans (Vicia faba L.). The results of the study have been published in the journal Basic and Applied Ecology.

The researchers show that in landscapes with a high proportion of semi-natural habitats and in landscapes with a high proportion of field bean fields, more bumblebees were found in field bean fields. In addition, bean yields were higher in these landscapes. The scientists recorded and observed the foraging behaviour of honey bees and wild bees in field bean fields in agricultural landscapes with different landscape compositions. They also determined yield parameters of individual plants. -Insect pollination has a positive effect on field bean yields. Our investigations showed that insect-pollinated plants yielded around 34 percent more beans per pod than plants that were inaccessible to insects," explains Doreen Gabriel from the JKI.

-For the pollination success of field beans, it is not only the bee density in the field that is important, but also which bee species collect on the flowers and how they do it. Bumblebee species with short proboscises often rob nectar from field beans by making holes in the calyxes. In contrast, most long-trunked bumblebees collect nectar regularly from the front of the flower, resulting in increased cross-pollination rates. However, there are hardly any studies that have investigated whether the behaviour of bees when collecting nectar is also influenced by resource availability in the landscape, i.e. landscape composition-, says first author Dr Nicole Beyer, who did her PhD at the University of Göttingen and now works at the Thünen Institute in Braunschweig. The study shows that short-tailed bumblebees predated more nectar on field beans when there was a high proportion of field beans in the landscape.

-Our study illustrates how landscape composition is also important for yields, as shown by the example of field bean. The availability of flower-rich habitats can improve the density of bees in fields, their foraging behaviour and their pollination performance-, concludes Catrin Westphal, head of the Functional Agrobiodiversity Department at Göttingen University.

Original publication: Beyer, N., Gabriel, D. & Westphal, C. (2022). Landscape composition modifies pollinator densities, foraging behaviour and yield formation in faba beans. Basic and Applied Ecology, doi: https://doi.org/10.1016/j.baae.2022.03.002


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