What keeps killing the bees?
April 15, 2013
From: U~T San Diesgo
Exact cause of colony collapse disorder still unknown; potential impacts are huge
By Mark Walker
Standing in a buckwheat patch in the heart of Pauma Valley, James Gibbs pulled the cover off a honeybee colony box to see how his livelihood was faring.
It’s an assessment beekeepers have approached with trepidation for close to a decade as a mysterious malady — or maladies — continues to kill at least half of their bees. This year’s losses are as much if not greater, according to commercial beekeepers in this region and nationwide.
The toll from colony collapse disorder threatens more than just beekeepers such as Gibbs: The agricultural industry, and ultimately the consumer, relies on bees to pollinate about one-third of all fruit and vegetable crops. Bees pollinate nearly 100 crops overall and have an estimated annual value of $15 billion to $20 billion because of the larger yields they help produce.
For Gibbs, checking his hives’ health is akin to stockbrokers monitoring the Dow Jones industrial average for daily gains and losses.
“We lost about 7,000 colonies this year,” said Gibbs, 87, the co-owner of Chaparral Honey in Valley Center. “We’ve had very, very serious kill-offs.”
While Gibbs said his company suffered a loss of about 30 percent during last winter, many of the 60 other commercial beekeepers in San Diego and Riverside counties saw about half of their bees die in that period.
“It’s pretty universal,” said Eric Larson, executive director of the San Diego County Farm Bureau. “We continue to get a lot of reports of losses.”
Apiarists and researchers place blame on virus-carrying mites and certain pesticides. Other contributing factors may include drought and bee interaction with disparate colonies that transmit lethal diseases. But pinpointing a precise cause remains elusive.
“No one thing seems to account for all these dramatic colony losses,” said Dr. James Nieh, who runs the Nieh Bee Lab at the University of California San Diego.
The U.S. Department of Agriculture’s research arm is compiling its annual survey of bee companies and plans to issue its findings early next month concerning hive fatalities across the country.
“We don’t have the report yet, but we’re hearing anecdotally that losses (are) very high,” said J. Kim Kaplan of the agency’s Agricultural Research Service.
Last year’s report, which pegged losses from managed honeybee colonies at 22 percent for the 2011-12 winter, was a relief to industry watchers after five years of substantial losses. Winter losses before colony collapse disorder typically ranged from 15 percent to 20 percent.
Nieh and his students examine the effects of parasites and pesticides on bees, with emphasis on a parasite called Nosema. Their research includes exploring how differing levels of Nosema affect colonies and how exposure to various pesticides might influence food flow into a colony.
The industry also is battling a parasite called Varroa destructor, which by itself can wipe out entire hives or colonies. A colony typically has 40,000 or more bees.
Chaparral Honey, Gibbs’ company, has about 100 bee boxes in the Pauma Valley. After nurturing his colonies to full strength, he and his staff truck the bees to the Imperial Valley for crop pollination.
The company derives most of its revenue from hive rentals, which run about $150 per colony. Some apiarists are charging upward of $200 per colony because of increased costs stemming from colony losses.
For Gibbs and many other commercial beekeepers, the agricultural season in California begins in February in the San Joaquin Valley, where more than 1.5 million hives are used to pollinate a vast almond crop.
From there, Gibbs’ bees work in this region’s avocado and fruit groves before making the trip to Imperial County, where they buzz among fields of broccoli, onions, blueberries and seed crops. Growers typically need 1.5 colonies per acre.
From his four decades as a commercial apiarist — after an earlier career as a university professor — Gibbs believes the primary culprit striking the bee industry is virus-transmitting mites. He also said the harm is multiplied because beekeepers often crisscross the nation to do business.
“Because of the utility of bees in pollination, they now move from coast to coast each year,” Gibbs said. “With a million or more colonies coming into California each year to deal with the crops in the San Joaquin Valley, diseases that may start in Florida are now quickly transmitted to other bees and spread across the country.”
He also said the losses tend to spike during times of below-average rainfall or harsh winters.
“Whenever we have conditions that are detrimental, the bees become more susceptible,” he said. “It’s not a simple thing, it’s usually a combination.”
Recently, the industry’s more than 20,000 commercial beekeepers nationwide have focused on a class of insecticides known as neonicotinoids, which were first used in 2005 — about the same time as major colony collapses.
In late March, beekeepers, the Sierra Club and other environmental groups sued the U.S. Environmental Protection Agency in federal court in Northern California. They are seeking an injunction that would order the agency to stop allowing the use of two neonicotinoids, clothianidin and thiamethoxam.
In response, EPA officials have said they are speeding review of those neonicotinoids.
Nieh suggested that bees infected with Nosema and then exposed to neonicotinoids may develop a more lethal infection that can quickly spread throughout a colony.
“Banning pesticides would only take one leg out of what is a four-legged stool,” he said of theories that numerous factors are causing major colony loss.
And doing so doesn’t mean exposure to potentially lethal chemicals would end.
“You can’t constrain bees to foraging in only one location,” Nieh said.
Dr. Eric Mussen, a leading bee researcher at UC Davis, said spraying pesticides only at night or in areas where honeybees aren’t placed could reduce the bees’ death toll by as much as 50 percent.
“The question increasingly seems to be the level of the wallop from the pesticide dose,” he said. “But that’s just one of the questions that still hasn’t been answered.”
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