After tumbling to a 23-year low in 2007, California's commercial honeybee population seems to be on the rebound - though a mysterious and deadly epidemic persists in ravaging some colonies.
Apiarists in the state, most of whom rent their bees to farmers for crop pollination, say this and last year's wet winters - and more plentiful greenery - may have helped temper the effects of "colony collapse disorder," a little-understood scourge that has virtually wiped out some bee stocks across California and the United States.
But other beekeepers say they've simply gotten better at compensating for the die-off by dividing their colonies, importing new queen bees or buying whole colonies outright (the number of bees in a commercial colony fluctuates through the year, ranging between about 20,000 and 150,000).
"We're learning new ways to deal with (colony collapse disorder), so the numbers are getting better," said Frank Pendell, president of the California State Beekeepers Association. "It's just like hitting your finger over and over with a hammer. You learn to stop doing it."
The number of honeybee colonies in California is at its highest level in seven years - good news in a state where the black-and-yellow bug represents a critical link in the multibillion-dollar food-production cycle. In their search for nectar, the buzzing insects unwittingly distribute pollen - the equivalent of male sperm - to the female part of plants. Nearly 100 California crops, including melons, sunflowers, carrots, cauliflower and almonds, rely on bee pollination.
The National Agricultural Statistics Service, one of the only state or federal agencies that track honeybees, counted 410,000 colonies in California last year, up from 355,000 in 2009 and a rock-bottom 340,000 in 2007.
Count considered low
In general, the national data under-represent the number of colonies because the annual survey is voluntary and does not include operations that strictly rent their bees for pollination; most industry watchers put the number of California colonies at 500,000 to 550,000.
That remains well below the recent peak of 620,000 colonies in 1989 (the records go back to 1987). Nevertheless, honeybee experts are heartened by what they see as marked improvement in the health of many hives - particularly after the 2007 nadir.
One factor may be Mother Nature. More rain in 2010 and 2011 may have boosted the bees' floral food supply, and lower summer temperatures may reduce heat-related stressors, according to Eric Mussen, a well-known bee authority at UC Davis.
"On the whole it looks like the bees are doing better," Mussen said. "With a little luck, this may be one of our better years."
Cyclical die-offs
The loss of 15 to 25 percent of a colony's bees over a winter is pretty normal, Mussen said. And over the history of apiculture - European honeybees were brought to the United States in the 1600s - mass deaths are not unheard of. Wild bee populations have plunged in recent years due to loss of habitat, and commercially raised bees have succumbed to cyclical die-offs due to a host of diseases and microbes.
Colony collapse disorder - first described in 2006 by a Pennsylvania beekeeper who lost most of his bees after trucking his hives to Florida for the winter - is striking in its devastation. The sickness seems to target the insect's gut, interfering with its ability to take in nutrients. While the disorder culls an average of one-third of each colony's bees in California and the United States, in some cases up to 90 percent of the workers simply fly off and die. Scientists are still struggling to find the culprit - or culprits.
Recent research suggests several causes working in tandem, including dry weather, poor food sources, environmental stress, insecticides, fungi, mites and viruses. Some have even blamed genetically modified crops and cell phone radiation.
Almonds need bees
While scientists continue to narrow the suspects, farmers are keeping a close eye on the bees' fortunes. No product has more at stake than the state's $2 billion annual almond crop.
Each year, the almond bloom in the Central Valley requires about 1.5 million honeybee colonies for pollination, or about half of all the commercial colonies in the United States. Beekeepers charged between $140 and $165 per hive this almond season, Pendell said; one acre typically requires two hives for pollination.
Tom Parisian, who tends 3,500 colonies in Vacaville, has changed the way he rents bees to almond farmers after colony collapse disorder claimed about half of his bees in 2008.
For instance, some growers use pesticides that experts have implicated in the bee plague. On days when farmers spray those chemicals, Parisian removes his hives. It's expensive and time-consuming, Parisian said, but if the tactic helps keep his bees healthy, he's willing to take the hit.
Parisian also supplements his bees' diet with syrup to boost protein levels and treats the colonies with anti-viral medicine.
"You can't tell which one or two things may be having an effect," he said. "But the bottom line is the bees came through last winter in better shape - probably better than they have been in 30 years."
Still, no cure for the disorder exists, and Mussen continues to hear from beekeepers who lose half of a colony seemingly overnight.
E-mail Kelly Zito at kzito@sfchronicle.com.
Read more: http://www.sfgate.com/cgi-bin/article.cgi?f=/c/a/2011/04/10/MN971IRGIA.DTL#ixzz1JhaSQiJv
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