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Western honey bee colonies at risk of collapse, study finds

Conrad Swanson, The Seattle Times on

Published in Science & Technology News

SEATTLE — One of nature's most important keystone species is working itself to death.

Colonies of honey bees — crucial pollinators for a wide variety of plants and cash crops — are at risk of collapse because of climate change, a recent study by scientists at Washington State University and the U.S. Department of Agriculture found.

Long and warmer fall months across the Pacific Northwest encourage bees to emerge from their colonies when they should be resting, said Gloria DeGrandi-Hoffman, a research leader at the USDA's Carl Hayden Bee Research Center in Arizona.

"When it's warm out, they fly and when they fly they're physiologically aging," said DeGrandi-Hoffman, who is also one of the study's authors. "It's very taxing to fly."

Come springtime, bees that should be emerging young and rested are instead elderly and infirm, she said. They're too old to care for younger bee generations, which in turn cannot care for the generations after them.

When the colonies sink below a certain threshold (around 5,000 bees), multiple things start to go wrong and the population spirals, said Brandon Hopkins, another author and manager of WSU's apiary program and laboratory. The bees will no longer be able to keep warm, nursing bees can't feed the developing brood and there won't be enough bees to forage for food.

 

"Everything falls apart," Hopkins said. "The whole system crashes."

All because of a few degrees' increase in temperature.

The study modeled many different climate scenarios for the decades ahead, said Kirti Rajagopalan, another author, and an assistant professor in WSU's Department of Biological Systems Engineering. How severe the warming trend continues for the Pacific Northwest depends on whether humans curtail greenhouse gas emissions and, if so, by how much.

Warmer fall and winter months don't happen every year, and the Earth will continue to see its natural variability, but climate change pushes each end of the spectrum to greater extremes than before.

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