Fri, Jun 21, 2019 - Page 7 News List

Biggest winter honeybee die-off yet, US study says


A beekeeper holds a frame from a hive box covered with honeybees in Lansing, Michigan, on Oct. 12 last year.

Photo: AP / Dale Young / Detroit News

Winter hit US honeybees hard with the highest loss rate yet, an annual survey of beekeepers showed.

The annual nationwide survey by the Bee Informed Partnership found that 37.7 percent of honeybee colonies died this winter, nearly 9 percentage points higher than the average winter loss.

The survey of nearly 4,700 beekeepers managing more than 300,000 colonies goes back 13 years and is conducted by bee experts at the University of Maryland, Auburn University and several other colleges.

Beekeepers had been seeing fewer winter colony losses until now, Dennis van Engelsdorp, president of the bee partnership and coauthor of the survey, said on Wednesday.

“The fact that we suddenly had the worst winter we’ve had ... is troubling,” van Engelsdorp said.

Some bees usually die over winter, but until the past couple decades, when a combination of problems struck colonies, losses rarely exceeded 10 percent, he said.

Bees pollinate US$15 billion of US food crops. One-third of the human diet comes from pollinators, including native wild bees and other animals, many of which are also in trouble, according to the US Department of Agriculture.

“We should be concerned on multiple levels,” said University of California, Berkeley, agricultural social scientist Jennie Durant, who released a separate study this week on loss of food supply for bees.

Year-to-year bee colony losses, which include calculations for summer, were 40.7 percent higher than normal, but not a record high, the survey found.

“The beekeepers are working harder than ever to manage colonies, but we still lose 40 to 50 percent each year... Unacceptable,” said Swiss bee expert Jeff Pettis, who was not part of the survey.

For more than a decade, bees have been in trouble with scientists blaming mites, diseases, pesticides and loss of food.

This past winter’s steep drop seems heavily connected to mites, van Engelsdorp said.

Beekeepers report that chemicals that kill mites do not seem to be working quite as well and mite infestation is worsening, he said.

Those mites feed on the bees’ fats, where the insects store protein and center their immune response.

Durant’s study in this week’s Land Use Policy found that changes in food supply in the Midwest’s Prairie Pothole Region, a hot spot for honeybee colonies, has been a major factor in losses. That area has lost wetland areas with clover bees feed on.

Other areas have been converted to corn and soy crops, which do not feed bees, she said.

“We’re not really worried about honeybees going extinct... I’m more worried that the commercial beekeepers will go out of business,” van Engelsdorp said.

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