Do wild bees complement honeybee pollination of confection sunflowers in Israel?

Complementarity between species in the use of flower resources can enhance the pollination services of diverse pollinator communities. To test for complementarity, we studied fine-scale patterns of flower visitation and contribution to seed set of the three locally dominant bee species (commercially managed honeybees and two wild, non-managed Lasioglossum species) visiting confection (non-oil) sunflower in central Israel. The three species differed in their temporal (time of day) and phenological (head bloom stage) visitation patterns but generally showed niche redundancy. Moreover, honeybees strongly outperformed the wild species in both visitation rates and single-visit contributions to seed set. We conclude that the present communities and densities of wild bees do not complement honeybee sunflower pollination in the studied system. Sunflower seed production in central Israel is currently dependent solely upon the high stocking rate and pollination efficiency of honeybees.