Honey bee (Apis mellifera) hive placement is more influential than orchard layout on the fruit set of a dioecious crop

Managers of insect-pollinated orchards face many decisions that can significantly influence crop yields, including managing pollination through use of beehives or the layout of cultivars in the orchard. Understanding the relative importance and interactions between these multiple decisions through empirical field trials is rarely possible, so modeling approaches can provide valuable insights and generate new hypotheses. Based on kiwifruit (Actinidia chinensis var. deliciosa (A. Chev.) A. Chev. ‘Hayward’), a dioecious fruiting vine, as an exemplar, we used a spatially-explicit system of differential equations on a lattice to explore the effects of overlap of male and female flowers, hive placements within the orchard, and orchard layout on the predicted pollination success. In our model, hive placement and orchard layout influenced the proportion of fruit set in an orchard more strongly than male and female flowering synchrony. Simulations with hives distributed evenly around the orchard had the most fruit set, while hives located at a single point resulted in relatively low fruit set. Our model showed that the effect of hive distribution was more important for fruit production than planting regime. We have demonstrated how such a model can be used to provide key information for orchardists to optimize their yields. Our model predicts that while orchard planting decisions are important, the consideration of hive placement during flowering is likely to have greater influence on final orchard productivity in functionally dioecious crops.