Heat hammers honey bees

by Kathy Keatley Garvey

July 12, 2008 12:01am

•  Bees spend more time trying to keep cool

•  ‘You’ll see honey bees collecting water everywhere’

The Central Valley’s record-breaking triple-digit temperatures are not only wreaking havoc on humans, but on honey bees.

On days when temperatures exceed 100 degrees, bees collect more water to cool the hive to protect immature bees and ward against a meltdown, says University of California, Davis bee specialist Susan Cobey.

“Bees reduce their flight activity for nectar and pollen, but collect more water. They spread droplets of water and then fan their wings to ventilate and cool the hive,” says Ms. Cobey.

“When the heat is really intense, the worker bees rev up the fanning and water circulation to prevent comb meltdown and death of the brood (immature bees),” says Ms. Cobey, a bee breeder and geneticist at the Harry H. Laidlaw Honey Bee Research Facility, part of the UC Davis Department of Entomology.

“Older bees will sometimes go outside the hive and sit in front of the hive and form bee beards until the heat relents,” she says.

Beekeepers know to locate their hives in shade and near ample water, such as a drippy faucet, Ms. Cobey says. “Beekeepers will often crack a hive to provide more air flow and if the bees don’t like it (the hole), they’ll plug it with propolis (plant resins collected by bees that serve as a cement or bee glue).”

Entomologist Lynn Kimsey, head of the Department of Entomology and director of the Bohart Museum of Entomology, says that in intense heat, honey bees desperately need more water to cool down the hive.

“They have to keep the interior temperature of the hive around 92 to 94. That’s a real problem when the temperature outside reaches 100 or 105 or more,” says Ms. Kimsey.

“You’ll see honey bees collecting water everywhere, from around leaky faucets, and in puddles, bird baths, fish ponds and swimming pools--any where there’s water,” Ms. Kimsey says.

Worker bees do all the work to maintain the hive. In addition to gathering nectar, pollen, propolis and water, they serve as air conditioners, architects, construction workers, nurses, dancers, guards, and undertakers, Ms. Cobey says.

But unlike the proverbial postman (“Neither rain, nor snow, nor sleet, nor hail shall keep the postmen from their appointed rounds”), bees don’t work in foul weather: in rain, heavy fog, or in a wind of more than 15 miles per hour, Ms. Cobey says. “And they don’t like the heat.”

Last winter the nation’s beekeepers lost about one-third of their bee population due to a phenomenon known as colony collapse disorder, in which bees mysteriously abandon their hives.

Cooperative Extension apiculturist Eric Mussen of the UC Davis Department of Entomology says that colony collapse disorder is probably the result of multiple factors, including malnutrition, pesticides, diseases, parasites and stress.

“The beekeeping industry is crucial to California’s $42 billion agricultural economy,” says Ms. Kimsey, who is rebuilding the bee biology program after faculty retirements and budgetary constraints decimated much of the program in the 1990s. “More than 90 different crops, with a total value exceeding $6 billion, require pollination. One-third of the food in our diet is pollinated by bees.”

Bees pollinate almonds, alfalfa, sunflowers, tree fruits and many other crops. California’s almond production soared this year to 740,000 acres, requiring two hives per acre.

California accounts for $6 billion of the nation’s $16 billion-pollination industry, says Mr. Mussen, who joined the UC Davis Department of Entomology in 1976. California also accounts for half of the nation’s sales of queen-and-packaged-bees stock, he says. “And we continually rank among the top four honey-producing states, along with North Dakota, South Dakota and Florida.”

The mission of the 76-year-old Harry Laidlaw Jr. Honey Bee Research Facility, one of the oldest honey bee research facilities in the country, is to meet the needs of California’s multibillion dollar agricultural industry and to address the nation’s growing concern about bee health and the declining bee population.

The 8,200-square-foot Laidlaw bee biology facility is home to laboratories, a honey bee food processing room, a large multipurpose room, glassed observation hives, offices and a wood shop.

(About the writer: Kathy Keatley Garvey is a communications specialist with the Department of Entomology at the University of California, Davis.)

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