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2009 Annual Report

UC Statewide IPM Program

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Sara Goldman Smith, staff research associate, UCCE Sutter/Yuba counties, checks a blue orchard bee shelter with nesting blocks in an almond orchard in Durham as almond bloom begins in February. This is one of six Butte County release sites in a UCCE–USDA study.
Photo by Theresa Pitts-Singer.

Scientists track blue orchard bees as promising pollinators for almonds

Blue orchard bees could supplement honey bees as pollinators in California’s almond orchards, reducing the risk of depending on a single pollinator species for the crop, according to research by UCCE personnel and scientists with the USDA–ARS Bee Biology and Systematics Laboratory in Logan, Utah.

Traditionally, commercial almond growers have used hived honey bees, but concern about the availability of enough affordable, healthy hives has increased.

 “When almond growers were paying up to $200 per hive for honey bees, they began looking for alternatives, and we’ve shown that blue orchard bees are a good possibility,” said project member Carolyn Pickel, UC IPM advisor in the Sacramento Valley.

“Blue orchard bees contribute to a more sustainable system too," Pickel added. “Growers don’t need to rely on a single pollinator, and they pollinate at cooler temperatures, which could improve pollination in the Sacramento Valley during cool springs.”

After studying blue orchard bees from three climatic regions of the Western United States, researchers determined those that are native to the foothills of California are better suited for the state’s hot climate, which would make commercial-scale handling less complex and less expensive than handling bees from Utah or Washington.

One disadvantage of blue orchard bees from the other two states is they develop too quickly for California’s longer summers and require cooling to survive, Pickel said. Native California bees might not require cooling, since they tend to develop more slowly in the larval and prepupal stages.

“However, native blue orchard bee populations are not yet commercially available, so techniques for handling bees from Washington and Utah must also be developed,” Pickel said.

Additional research also will be required to study problems that might occur when Washington and Utah bees breed with California species, Pickel added.

Pickel, along with James Cane and Theresa Pitts-Singer from the USDA Logan Bee Laboratory, released blue orchard bees from all three states into three separate almond orchards in 2008. In 2009, they released six separate populations, including offspring from 2008 experimental orchards and commercially purchased bees from Washington and Utah.

Field observations to document nesting activities of adults and the developmental stages of their offspring complement data collected from offspring reared at the Logan bee laboratory in an incubator that simulates California weather. Researchers will use the data to develop almond pollination guidelines for managing each of the different species.

“Growers or beekeepers could use this information to sustain and enlarge a population from year to year, whether it was native to California or from further north,” Pickel said.


Carolyn Pickel
(530) 822-7515

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