Pollination services provided by wild and managed bees to apple crops of the midwest

Native, wild bees are important pollinators for both crop and wild plants.  As concerns continue over the availability and cost of honey bees, attention has turned to native, wild bees as pollinators. However, little research has documented the ability of native, wild bees to provide sufficient pollination for pollinator-dependent crops. In this research, we examined the contribution of honey bees and wild bees to apple fruit set, and whether wild bees alone could meet pollination needs. Over three growing seasons (2011-2013) fruit set was measured at twenty orchards in southern Wisconsin, half of which used managed honey bees. Across years, apple fruit set was negatively related to frost damage indicating that environmental factors contribute significantly to variability in fruit production.  In addition, fruit set was positively related to the richness of wild bee species.  Despite the fact that many farmers use honey bees to enhance apple pollination, neither the presence of managed honey bees on the orchard nor the abundance of honey bees was significantly related to fruit set.  This research suggests that at orchards with a high diversity of wild bees, farmers could save on production costs by relying solely on wild bees for pollination.  Efforts to maintain or enhance wild bee diversity on apple farms could additionally enhance fruit set.  These findings in apples are consistent with those from other agroecosystems that have shown that wild bees are important crop pollinators and could provide insurance against declining honey bee populations.