Pollination Efficiency of Native Bees and Honeybees to Apple in Norway

Abstract

Crop pollination is traditionally managed with the European honeybee (Apis mellifera). However, the supply of honeybees may not be sufficient to meet the increasing global pollination demands and beekeepers are met with increased challenges with honeybee health. In addition, accumulating evidence shows that traditional guidelines for crop pollination are not promoting optimal yields. Consequently, new management solutions for pollination are warranted and interest in wild bees as crop pollinators has emerged. To determine the differences between pollinator genera in single-visit pollination efficiency on apple, pollinators were allowed to forage on previously unvisited flowers, and the pollinated pistils analyzed for pollen quantity and germinated pollen tubes. Solitary bees and bumblebees had a higher pollination efficiency to apple compared with honeybees; they had higher single-visit pollen deposition effectiveness and deposited more pollen grains that formed pollen tubes. However, honeybee abundance is usually much higher compared with the native bees. Therefore, increasing the abundance of native bees with targeted management efforts has the potential to increase overall pollination services to apple. Moreover, it appears that the relative importance of functional traits in apple pollination varies among bee genera; traits that facilitate stigmatic pollen deposition of solitary bees are not key traits for corbiculate species. Therefore, it is important to gather knowledge on different species and their contributions to pollination in different cropping systems.