Assessing Blue Orchard Bee () Propagation and Pollination Services in the Presence of Honey Bees () in Utah Tart Cherries

is a commercially available, native solitary bee species recognized for its propensity to forage upon and pollinate tree fruit crops such as apple, almond and cherry. This study evaluated the implementation of co-pollination with honey bees in central Utah commercial tart cherry orchards during 2017 and 2018 bloom. Three paired 1.2 ha sites were selected for evaluation of cherry fruit set and yield with and without managed releases alongside the standard honey bee hive stocking rate of 2.5 hives/ha. supplementation did not measurably increase cherry fruit set, fruit per limb cross-sectional area or fruit weight. The lack of differences in yield is likely a consequence of local saturation of pollinator services supplied by managed honey bees throughout experimental orchards, such that no additive benefit of managed releases were measurable. An increase in managed populations was achieved in 2017 but not 2018, possibly due to unknown changes to orchard management or environmental factors. While flying in Utah tart cherries may support sustainable in-field bee propagation, their subsequent impacts on tart cherry yield were not detected when paired with standard stocking densities of honey bees.