Renting commercial beehives is, on average, the single most expensive production cost for Maine’s blueberry growers, according to Frank Drummond, an entomology specialist and professor of insect ecology at the University of Maine.

“On the other hand, it’s also one of the most important,” he was quick to add.

“If you don’t manage all your insects or weeds, you still have some crop loss,” Drummond said. “But blueberries have to have bees moving pollen around.”

Drummond is leading a multi-pronged research project studying various aspects of bees — commercial bees and native bees — and their critical work pollinating blueberry fields in the spring. The five-year, $3.5 million project involves a number of colleagues at the University of Maine, graduate students and researchers from other states.

Primary fieldwork for the study, now in its third year, primarily is being conducted in Washington and Hancock counties, the leading producers of wild lowbush blueberries, though some research is also being conducted in other blueberry-producing coastal counties, such as Waldo, Knox and Lincoln counties.

“The whole purpose of this project is to look at what are some of the best pollination strategies that growers might be able to use,” Drummond said.

‘A free natural resource’

The research stems from challenges with native and commercial bee colonies in the past decade. Honeybee populations are experiencing overwintering losses and colony collapse, Drummond noted, and native bees are disappearing in some areas, notably in southern New England and in the South.

Some growers rely heavily, almost exclusively, on native bees — “a free natural resource,” Drummond said. “If you had to replace that … then it becomes your most important production cost.”

The project is studying the role native bees play in blueberry pollination, the status of native bee populations, and which species of bees are best for adequate pollination. Other aspects of the research include studying commercial bees and factors that affect their survival, such as disease and the use of pesticides in blueberry agriculture.

For example, researchers are looking at managing the landscape surrounding blueberry barrens to determine how those practices can increase native bee populations and contribute to pollination. They are studying types of pollinator plants that can be grown near blueberry fields to provide forage for native bees and strengthen their colonies.

Product of environment

Blueberry fields surrounded by other blueberry fields have low populations of native bees, as do blueberry fields bordered by coniferous — softwood — forests, which is common in Washington County. By contrast, blueberry fields surrounded by meadows or deciduous — hardwood — forests have higher native bee populations. If there is a lack of suitable vegetation that hinders native bee populations, then growers need to rely on commercial bees for adequate pollination.

“We’re looking at what (pollinator) plants are best suited for Maine,” Drummond said.

Researchers are testing a plant mix with the goal of providing a good food source for bees before and after blueberries bloom, vegetation that will overwinter well but will not encroach upon lowbush blueberries.

The project also includes developing economic models to better enable blueberry growers to make decisions about how many colonies of bees they need to rent in the spring. The researchers already have developed a model to predict pollination levels with native bees and commercial bees.

“Right now, we’re incorporating that into the economics of blueberry production,” Drummond said, which would allow farmers to calculate how much they need to invest in commercial beehives. Growers would be trained to use the model when it is in its final form.

The research into pesticides, particularly fungicides, which growers normally apply just before the blueberry bushes bloom, has shown only a slight negative impact on bees, according to Drummond.

“But it does not result in any colony losses,” he added.

Possible negative impact

Growers can feel “pretty comfortable,” Drummond said, about using fungicides right before bloom to manage disease. However, they should halt application of fungicides after bloom. Growers already follow this practice, according to Drummond, and the new findings reinforce it.

The study also is looking at the impact of neonicotinoid insecticides and their impact on bees. Neonicotinoids are synthetic insecticides with low toxicity to people, but bees are very sensitive to them.

The research is examining large blueberry barrens that are intensely managed by businesses as well as small fields where blueberries are grown organically.

“The point is not to develop a one-size-fits-all (approach),” but to develop strategies that may be better suited for the different types of production, Drummond said. “They’re extremely different,” he noted.

Another aspect of the project is outreach to blueberry growers. Drummond put on a series of workshops to teach growers how to recognize native bees and gauge what level of pollination they are receiving from them.

The research project involves biologists, economists and anthropologists from the University of Maine, as well as researchers from other states.

The next couple of years, we hope to fine tune these projects and develop more confidence in the data,” Drummond said.