Flower visitors and fruit set of sweet cherry in Germany

Mason bees (Osmia spp.) are efficient fruit tree pollinators that can be encouraged to occupy and breed in artificial nesting material. In sweet cherry orchards, they are occasionally used as an alternative managed pollinator as a replacement for or in addition to honey bees (Apis mellifera). Yet, the lack of practical guidelines on management practices, e.g., optimal stocking rates, for both mason bee nesting material and honey bees might compromise pollination service provision. In this study, we assessed the relationship between stocking rates (honey bee hives and mason bee nesting material) and the abundance of honey bees and mason bees in 17 sweet cherry (Prunus avium) orchards in Central Germany. We furthermore performed a pollination experiment to explore the interactive effect of mason bees and honey bees on sweet cherry fruit set. In the orchards, both honey bee and mason bee abundance increased with increasing stocking rates of hives or nesting material, respectively. Honey be..., , , Cherry flower visitors and cherry pollination

Fieldwork was carried out in spring 2020 in orchards within the federal states Sachsen-Anhalt and Thuringia, Germany (Figure 1). Both federal states are dominated by agriculture (>60% of land cover). We selected 17 sites, of which two were experimental orchards and 15 were commercial mixed fruit orchards (Table S.1). The experimental orchards are owned by research institutions for conducting research experiments but are managed as commercial orchards in order to simulate agriculturally field-realistic conditions. The size of the orchards devoted to sweet cherry (Prunus avium) cultivation ranged between 0.2 ha and 36 ha (6.6 8.6; mean SD). Distances between field sites were >2 km (47.9 28.9 km; mean SD) to ensure spatial independence.
Pollination management consisted of providing honey bee hives and nesting material for mason bees (Osmia cornuta). Though Osmia bicornis is common in the study region, its flight period does commence ...