Maine news, sports, weather from Portland Press Herald / Maine Sunday Telegram, Portland, Maine

July 25, 2012

Maine blueberry farmer lures tiny but mighty allies

An organic grower uses nest boxes and forage plants to attract wild bees to pollinate his crop.

By Lynn Ascrizzi / Special to the Press Herald

In the organic, wild blueberry fields at Twitchell Hill Farm in Montville, a rosy green blush of new growth has been emerging from underground stems since early spring. Now, the white, bell-shaped blossoms that clustered on tender stalks are ripening into small, dark-blue fruit, promising a late-summer berry crop raised without pesticides or herbicides.

But instead of depending on only honey bees to pollinate the 15-acre blueberry field, grower Doug Van Horn of Freedom has launched a project to attract tiny, wild pollinators called mason bees.

"It looks like a bee, but it's the size of a housefly," he said.

But size doesn't matter when it comes to this hard-working, native pollinator, he said. "They're about four to five times more effective as spring-season pollinators than honey bees," said Van Horn, who has tended the organic blueberry fields for more than 35 years.

There are 12 species of tiny bees commonly called mason bees that are associated with Maine blueberry fields, according to insect ecologist Frank Drummond, Ph.D., of the University of Maine at Orono.

Mason bees do not create colonies of busy worker bees that collectively produce honey and beeswax. With no hive or honey to defend, these native bees are unlikely to sting, and their sting is mild, Drummond said.

To lure these productive little pollinators into his fields, Van Horn had a local woodworker create specially designed mason bee nesting boxes made of pine, hemlock and basswood.

The boxes, roughly 8-by-8 inches in size, are comprised of 20 wooden tubes with about 1/4-inch holes.

"The bees go into the holes, lay eggs and deposit nectar and pollen, before they seal off the entrance. The eggs turn into larvae, and later, the larvae spin cocoons, which overwinter. In spring, they emerge as a fully mature bee," said Van Horn, 67.

Mason bee boxes are available commercially. But Van Horn did extensive research to incorporate what he hopes are the best designs. Moreover, his nesting boxes were created with whimsical variations.

"Mason bees don't like order. They like more random designs," he said.

His mason bee nesting box project was funded, in part, by a $4,300 grant he received from the Natural Resources Conservation Service, a U.S. Department of Agriculture program.

"They have a program for organic growers to improve organic farming operations," he said. The federal grant provided funds to create an access road to the blueberry fields, to remove weed and brush growth, to plant pollinator-attracting native plants and to create mason bee nesting boxes.

Van Horn is one of about 50 wild blueberry growers farming organically in the state, according to the University of Maine at Orono. Altogether, there are about 600 blueberry growers in Maine.

ALTERNATIVE PRACTICES

On a blustery day this spring, Van Horn was at Twitchell Hill, inspecting the 18 mason bee nesting boxes he had recently installed around his blueberry fields. With him that day was insect ecologist Drummond, who brought with him UMaine botanist Alison Dibble, Ph.D., and graduate students Kalyn Bickerman and Eric Venturini.

"There is renewed interest in native bees because of problems with honey bees caused by colony collapse disorder," Drummond said, referring to worldwide die-offs of honey bee populations, a phenomenon first noticed in 2006.

"It's caused in part by the synergistic reactions of bees being exposed to pesticides, viruses and fungal pathogens, parasitic mites and poor diet," he explained.

But attracting native pollinators involves a lot more than installing nesting boxes. Drummond also is keenly interested in land stewardship practices by farmers and how those affect pollination, native bee communities and honey bee populations.

(Continued on page 2)

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