Friday, December 13, 2013
By Lynn Ascrizzi / Special to the Press Herald
(Continued from page 1)
Organic blueberry grower Doug Van Horn is using varied nesting box designs for the small wild pollinators.
Organic blueberry grower Doug Van Horn, left, and Frank Drummond, an insect ecologist at the University of Maine at Orono, inspect a nesting box for native bees at Twitchell Hill Farm in Montville.
Lynn Ascrizzi photos
MAINE ORGANIC FARMERS AND GARDENERS recommends "Farming for Bees: Guidelines for Providing Native Bee Habitat on Farms," by Mace Vaughan, Matthew Shepherd, Claire Kremen and Scott Hoffman Black, 2007, The Xerces Society. The 43-page book is available as a pdf download or to buy ($15).
AVERY YALE KAMILA is on vacation. Her "Natural Foodie" column will return soon
"For instance, we have been looking at the amount of (plant) forage on farms that affects bees, the effects of pesticides used and the overall landscape that farms are embedded in," Drummond said.
That day at Twitchell Hill, UMaine student Venturini took soil samples along a three-quarter-acre strip of uncultivated land adjacent to the blueberry fields. By early June, the half-acre strip had been cultivated, limed and seeded with a trial mix of wildflower seeds known to attract bee pollinators. The mix, which contains both perennials and self-seeding annuals, was donated by Applewood Seed Co. of Arvada, Colo.
"If this mix works well, they (Applewood) will promote it," Van Horn said.
Seeds from a dozen wildflowers were included, such as, perennial lupine, wild sunflower, purple coneflower, Indian blanket, showy goldenrod, New England aster and bergamot.
"In a field like this, it wouldn't surprise me if there were 20 different species of wild bees, such as mason bees, orange-belted bumblebees, digger bees and sweat bees," Drummond said. "Out of the 237 wild bee species in Maine, slightly over 100 of them visit blueberries. Hopefully, the forage plants will attract a bunch of them," he said.
So far, the results of this first-year nest-box experiment are encouraging.
"Out of the 18 boxes, better than 50 percent have inhabitants. The holes are plugged up, which indicates mason bees have laid eggs," he said.
In summer, larvae hatch from the eggs. Adult bees emerge from their pupal stage by fall or winter but hibernate in their insulating nests until early spring, he added.
"I'm curious to know which box designs they will like best. That's what farming is about. It's waiting for nature to happen," Drummond said.
Drummond, who lives in Winterport, has been with UMaine for 25 years.
"If you put nesting boxes out, they will attract mason bees. It may take a year before you get the full results. A UMaine study in the mid-1990s showed a fourfold increase of mason bees in blueberry fields that had nesting boxes," he said.
Only about 20 blueberry growers in Maine are providing nesting boxes for mason bees, he added.
"I'd like to see a lot more. And not just nest blocks. I'd like to see more growers encourage native pollinators by selecting pest management strategies that reduce exposure of insecticides to bees and enhance flower sources."
HONEY BEES STILL RELIED ON
"But it's not just organic growers who are encouraging pollinators. Some conventional growers are planting pollinator strips, too," Drummond said.
One such conventional blueberry grower is Paul Sweetland of Searsmont. He leases 100 acres of blueberry fields in Hope, Rockport, Liberty and Waldoboro and also manages 1,300 acres of blueberry fields through Coastal Blueberry Service.
"I rely heavily on honey bees. I am always looking to use insecticides that won't harm the bees. We try not to spray anything when blueberries are blossoming," he said.
Sweetland said he keeps weeds out of the fields with herbicides.
"We have a lot of natural habitat in the areas that have insects that help with pollination. The native bees have been important to pollination," he said.
Numerous studies show that cultivated fields close to natural areas like woods, pastures or meadows have more wild bees.
Organic grower Theresa Gaffney of Highland Blueberry Farm in Stockton Springs maintains 25 acres of wild blueberries with her husband, Thomas Gaffney. She believes insecticides contribute to native and honey bee declines and disrupt a delicate ecological balance.
"People put insecticides on their fields. Well, what is a bee? An insect! It boils down to this: No bees, no food. Especally for the wild Maine blueberry. It doesn't pollinate itself. In order for us to have that bumper crop, we have to have good pollination."
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