Surrounding landscape and spatial arrangement of honey bee hives affect pollen foraging and yield in cranberry

Abstract Honey bees are the most important managed pollinator in the world. Recent trends suggest, however, that the demand for their pollination services is growing faster than the available supply. Therefore, it is critical to determine the most efficient management practices to maximize their use for crop production. One factor known to influence the efficiency of crop pollination is the availability of alternative, non-crop floral resources. These resources can vary as a function of the landscape surrounding a farm as well as local management practices within a farm. However, little is known about how the foraging behavior of honey bees on the target crop responds to the spatial arrangement of hives or the composition of the surrounding landscape. In this study, we collected pollen from pollen traps on honey bee hives placed on commercial cranberry marshes in central Wisconsin (USA). Individual marshes were selected to fall across a gradient of surrounding landscape from high- to low-woodland. Within each marsh, hives were placed either adjacent to wooded habitat, adjacent to a water reservoir, or in the center of the marsh. Honey bees from hives near water reservoirs collected a lower proportion of cranberry pollen than honey bees near the wooded area or at the center of the marsh. However, honey bees collected the same number of cranberry pollen grains and total pollen biomass irrespective of hive location or the surrounding landscape. Honey bees from hives located near water reservoirs, relative to the other two hive locations, tended to collect more pollen from fewer plants (low evenness). Cranberry yield did not vary as a function of the proportion of cranberry pollen collected or total number of cranberry pollen grains collected, but yield was higher at marshes located in low-woodland landscapes relative to those in high-woodland landscapes. We conclude that the location of hives on a cranberry marsh in relation to non-crop habitat does not affect yield allowing growers to place hives where it is convenient, although placing hives near water reservoirs should provide bees with a more diverse pollen diet.