Pollination role of native bees studied
Research looks at effectiveness of native bees.
The price tag for renting honeybees for apple pollination, just $35 per hive a few years ago, now tops $100 in some regions. At one to two hives per acre, that’s a serious input cost for the nation’s apple growers. Not surprisingly, some orchardists are looking to native bees as an alternative, or at least as a back-up pollination choice.
A major research project is under way in Pennsylvania to answer many of the unknowns about the role and limitations of native pollinators in apple production. Some of the questions it will ask include: How far will native pollinators will fly? How susceptible are they to pesticides? What’s needed for border habitat to support bees before and beyond apple pollination season? How effectively do smaller bees pollinate? What impact do they have on fruit quality and yields?
Participants in the project include local growers, the Xerces Society Pollinator Conservation Program, Pennsylvania State University, and the Pennsylvania Department of Agriculture, with funding and support from the U.S. Department of Agriculture’s Specialty Crops Research Initiative, the USDA’s Natural Resources Conservation Service, several private foundations, and Ernst Conservation Seeds.
“The Mid-Atlantic apple-growing region is ideally suited for native bees,” explained Dr. David Biddinger, tree fruit entomologist at the Penn State Fruit Research and Extension Center at Biglerville. “We have lots of small orchards on hillsides surrounded by wood lots and fencerows—a mix of natural and agricultural land. We have several farms of 500 to 1,000 acres that have been using native bees only for almost 30 years in their orchards. These are fresh-market growers and they need big fruit, and they’re not seeing any losses from relying on native bees.”
“Honeybees are generalists,” said Biddinger. “They don’t just go to the apples; they go to dandelions and all kinds of flowering plants. Osmia bees like the blue orchard (mason) bee are more specialized for fruit trees. They are less distractible, and they are free, which farmers like. We are also working to develop Osmia bees as managed pollinators that growers can raise and move within orchards like honeybees.”
The Pennsylvania research is expected to produce a decision model to help growers evaluate pollination alternatives, including orchard locations where it’s better to bring in honeybees versus relying only on native pollinators and how many hives would be needed.
Dr. James Cane at the USDA Agricultural Research Service bee laboratory in Utah, advises growers not to switch to native pollinators without first doing research.
“Tiny orchards in the Northeast can get great pollination from native bees, but a 500-acre block of irrigated trees in the Pacific Northwest must bring in bees,” Cane said. “In arid areas that were scrub desert, the right kinds of native bees may be missing. But someone on the west side of the Cascades and adjacent to streams with alternate bee forage may be an exception.”
For growers considering the use of native bees, Biddinger recommends the publications How to Manage the Blue Orchard Bee as an Orchard Pollinator, by Jordi Bosch and Bill Kemp, available free online at www.sare .org/publications/bob.htm, and Managing Alternative Pollinators, from the Xerces Society.
Xerces offers an interactive map where growers click on a state for region-specific native bee, plant, and pesticide guides (www.xerces.org/pollinator-resource-center).
Additional online information is available at the Native Pollinators in Agriculture Work Group (www.agpollina tors.org), the Pollinator Partnership (www.pollinator.org), or in USDA publications at www.nrcs.usda.gov/technical/ ECS/data base/technotes.html.
Edith Munro writes for U.S. and Canadian publications on agricultural and environmental issues.