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Could blue orchard bees replace honeybees for pollination?

With the disturbing decline of the honeybee population over the past few years, orchard growers are now looking for viable alternatives in order to manage the pollination of their trees and plants. Luckily, recent research has shown that blue orchard bees (Osmia lignaria) may be a sustainable option in tart cherry orchards.

Natalie Boyle, an entomologist at the U.S. Department of Agriculture, suggests that a simple change in the layout of the bees’ nesting boxes could make blue orchard bees more likely to remain in the orchard to nest.

While the honeybee is a social bee species that gathers in colonies, the blue orchard bee is more solitary and nests in the cavities of wood, stems, or even artificial materials like cardboard tubes. This difference in preferred nesting requires that growers make the necessary changes to nesting sites if they want blue orchard bees to take up residence in their orchards.

Boyle laments that management practices for commercial pollination with the blue orchard bee haven’t been as well researched as those of the honeybee. She is looking to change that, saying “This study shows that by simply changing the availability and distribution of nesting sites in the orchard, we can substantially increase overall blue orchard bee nesting success in a commercially managed orchard.”

In order for blue orchard bees to become a cost-effective managed pollinator, they must be willing to remain in the orchard after they are released – which has been an issue in the past.

By changing the nesting arrangement from a large central nesting location with small perimeter nests to small nesting boxes spread evenly throughout the orchard, Boyle found that the blue orchard bees were much more willing to stay and procreate.

While both setups showed a successful return of bees to the nesting sites, the nesting rates were significantly higher in the uniform nest-box distribution model. Occupancy of nest-tubes increased along with the number of live larvae per location and larvae per individual nest tube.

Although the study did not evaluate the blue orchard bees’ impact on pollination and orchard yield, the researchers are planning a follow-up experiment in 2017.

In the meantime, Boyle states, “We hope that this study provides practical information that orchardists can use to incorporate blue orchard bee pollination into their current management efforts, particularly with varieties that have been historically fruit set-limited when honey bees are used alone.”

More information can be found in the Entomological Society of America’s Journal of Insect Science.

By Connor Ertz, Staff Writer

Source: Entomological Society of America

Image: USDA

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