Maintaining Forests, Wildflower Fields Around Orchards Can Boost Pollination
A new study by researchers at Pennsylvania State University found apple orchards surrounded by forests and bordered by wildflower-rich edges have more bees than orchards that lack such features. These findings are especially important given the rising cost of honeybee rentals.
Managed honeybees and more than 200 different species of wild bees are found in Pennsylvania’s apple orchards. Some of these bees, including mason bees (Osmia spp.) and mining bees (Andrena spp.), are especially good at working apple pollination. According to David Biddinger, a co-author of the study and research partner associated with the Integrated Crop Pollination project, a single Japanese orchard bee (Osmia cornifrons) can visit 2,450 apple blossoms in a day.
Both wild and managed bees need access to pollen and nectar, especially when orchards are not in bloom, says Biddinger, a Penn State tree fruit entomologist. The new study found that wild flowering trees and bushes blooming in nearby forests and along orchard edges, and some flowers on the orchard floor provide these important nutritional resources. Biddinger notes that farmers benefit from maintaining flowering plants in and around their orchards.
“The current recommended honeybee stocking rate for fruit crops is two hives per acre, but most Pennsylvania apple growers use much less, and many none at all — with no negative impact on yields since most fruit are thinned anyway to get adequate fruit size and quality,” he says. ”There doesn’t appear to be a pollination deficit in Pennsylvania apples as long as adequate bee habitat is within 200 yards of the orchard.”
In addition to flowering plants, “adequate bee habitat” includes places for wild bees to nest and areas where they are protected from pesticide sprays. Woodlots, fencerows, and brush piles provide wood that cavity nesting bees (like mason bees) can nest in. Mowing orchard edges occasionally can open up bare soil for ground-nesting bees. However, mowing too low and too frequently will reduce the number of flowering plants that bees can access to collect pollen and nectar.
Another recent study in New York apple orchards found that wild bees were less impacted by pesticide sprays when orchards were surrounded by forest and other types of natural habitat. However, Biddinger warns that, “Many [wild] pollinators of tree fruit are univoltine, so that they only have a single generation that can be wiped out with a single mis-timed toxic spray.”
Biddinger and his collaborators are now investigating which bees are pollinating Pennsylvania’s cherry orchards and how growers can best support those bees and the pollination they provide.