CORVALLIS, Ore. — A new study sheds light on the amount and variety of pollen available to honey bee colonies used in five major pollinator-dependent crops in Oregon and California — including California’s massive almond industry.
“Well-nourished bees can better withstand other stressors such as parasites, insecticides and the stress of long-distance transport."
The collaborative study, led by Oregon State University and Texas A&M University researchers, found that almond, cherry and meadowfoam crops provide abundant pollen. However, highbush blueberry and hybrid carrot seed crops may not meet honey bee nutritional needs. The study was published in the Journal of Economic Entomology.
The western honey bee is the primary pollinator for many fruit, nut, vegetable and seed crops that rely on bee pollination to produce high yields and quality. Both pollen abundance and pollen diversity are essential for colony growth and survival, said Ramesh Sagili, corresponding author of the study and associate professor of apiculture and honey bee Extension specialist in Oregon State’s College of Agricultural Sciences.
“Pollen diversity is important for the growth and development of bees,” Sagili said. “Low amounts of pollen availability to honey bee colonies can dramatically affect brood rearing.”
Nectar and pollen provide essential nutrients. Pollen, the colony’s primary protein source, varies in nutritional content but generally provides amino acids, lipids, vitamins and minerals vital to larval development, fat body formation and egg production in the queen.
“Well-nourished bees can better withstand other stressors such as parasites, insecticides and the stress of long-distance transport,” Sagili added.
Migratory beekeeping and crop nutrition gaps
Each year, more than 1 million hives are trucked to California for almond pollination alone. Altogether, approximately 2.5 million managed colonies are used annually in crop pollination throughout the United States.
Renting colonies for pollination is a major source of income for commercial beekeepers. But moving bees between crops exposes them to varied nutritional conditions, which can include temporary pollen deficiencies if the crop lacks essential nutrients and bees cannot access alternative forage.
Sagili emphasized that blueberry and hybrid carrot seed crops may pose nutritional challenges for honey bee colonies, particularly if bees lack access to additional forage or protein supplements during bloom.
“It’s crucial for beekeepers and crop producers to understand the pollen abundance and diversity that honey bees encounter during crop pollination,” he said.
Low pollen diversity in almonds despite abundance
In the study, researchers worked with 17 migratory commercial beekeepers during the 2012 growing season. They installed pollen traps on at least five colonies at each of five crop sites — almond, cherry, meadowfoam, blueberry and carrot seed — and collected pollen samples during peak bloom periods between February and August.
While California’s almond orchards — more than 1 million acres — produced large quantities of pollen, the samples showed low pollen diversity, especially compared with cherry and meadowfoam.
“We think the reason for that is almonds bloom early in the year when there are so few plant species in bloom,” Sagili said. “Bees have few other forage options and primarily rely on almond pollen.”
This lack of pollen variety was especially pronounced in areas of the San Joaquin Valley where few other crops bloom concurrently with almonds.
Recommendations for beekeepers and growers
The researchers recommend that beekeepers working in crops with low pollen diversity, such as highbush blueberries and hybrid carrot seed, monitor their colonies and provide supplemental nutrition as needed. Commercial protein supplements can help maintain colony strength and resilience.
In addition to Sagili, co-authors of the study include Ellen Topitzhofer, Hannah Lucas, Priyadarshini Chakrabarti and Carolyn Breece of Oregon State’s Honey Bee Lab, and Vaughn Bryant of the Palynology Laboratory at Texas A&M University.
Funding for the study was provided by the Oregon State Beekeepers Association.
Previously titled Researchers determine pollen abundance and diversity in five major pollinator-dependent crops
