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Home HortScience Bumble Bees: the New Buzz for Cranberry Growers
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CORVALLIS, OR—No matter how technologically advanced, cranberry growing operations still rely on old-fashioned insect pollination for berry production. Honeybees have historically provided this service, but the recent decline in honeybee populations has caused concern across the cranberry production industry.

"Cranberries require outcrossing by insect pollinators," explained Melissa Broussard, lead author of a study published in HortScience. "The European honeybee is used extensively in North America to provide pollination services for cranberry, but recent threats to honeybee health and the resulting decrease in available hives highlight the need to identify alternative pollinators." Brossard added that cranberry flowers are best accessed by "buzz pollination", but honeybees do not buzz-pollinate, so are considered less effective than other bees at removing pollen from cranberry flowers—another reason to find alternative bee species.

Cranberries bloom from mid-May to mid-July in Oregon. The typically cool, overcast, and windy weather during these months is not conducive to foraging by honeybees and can dramatically reduce their pollination efficacy. "Native bees adapted to the coastal weather conditions have the potential to be "superior pollinators"," noted the authors.

To find out more about the native species buzzing through the cranberry-growing region of Oregon, Broussard and colleagues from the Department of Crop and Soil Sciences at Oregon State University collected bees over two growing seasons; in all, 1330 bees were collected, representing five families, 13 genera, and over 27 native species. The scientists discovered a higher abundance of bumble bees, metallic sweat bees, and small sweat bees than honeybees. Bumble bees comprised 25.1% of all bees captured, with five species represented.

The team correlated bee foraging behaviors with temperature and wind conditions and compared pollen loads from honeybees and native bees foraging on cranberry flowers. Analysis of temperature and wind speed data indicated that both were significantly predictive of honeybee and bumble bee foragers. "Based on our results, bumble bees in general, and B. vosnesenskii in particular, may be providing significant pollination services for Oregon cranberry farms," Brossard said.

The research findings provide good news for Oregon cranberry growers; the natural abundance of native bumble bees may help growers reduce their dependence on more expensive honeybees, resulting in lower operational costs.

The authors stressed the importance of maintaining current native bumble bee populations. "If wild bumble bees are to be relied on for pollination services, it is critical that conservation efforts are developed to maintain and improve existing populations."

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The complete study and abstract are available on the ASHS HortScience electronic journal web site: http://hortsci.ashspublications.org/cgi/content/abstract/46/6/885

Founded in 1903, the American Society for Horticultural Science (ASHS) is the largest organization dedicated to advancing all facets of horticultural research, education, and application. More information at ashs.org


 

Original Article:

Native Bees, Honeybees, and Pollination in Oregon Cranberries
Melissa Broussard, Sujaya Rao, William P. Stephen, and Linda White
HortScience 46:885–888. [Abstract] [Full Text] [PDF]

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