Honeybees are still in trouble.
Over the past year, almost 29% of honeybee hives in the USA have died off, less of a loss than was reported in 2007 and 2008.
But it's still an unsustainable situation for the insects responsible for pollinating many important food crops, according to a survey released Tuesday by the Apiary Inspectors of America and the Department of Agriculture's Honey Bee Lab.
"This is the third winter in a row where we've lost almost a third of the colonies," says Dennis van-Engelsdorp, Apiary Inspectors president.
The hive loss reported was 35.8% in 2008 and 31.8% in 2007. Beekeepers start new hives, but it's expensive and time-consuming. VanEngelsdorp worries that some of the USA's 900 or so migratory beekeepers may go out of business because of the losses.
Bees are dying for reasons known and unknown. The known reasons include new fungal diseases and a parasite called the vampire mite, which was introduced from Asia in the 1980s.
What's unknown is the phenomena called colony collapse disorder, in which healthy worker bees fly away, leaving the hive, honey, queen and immature workers to die. "It's altruistic suicide," vanEngelsdorp says. "The workers somehow know they're sick, and in an attempt to stop their sisters from getting infected, they fly away."
But no one knows what's making them sick.
"It might be nutrition, new and changed pathogens, and also possibly pesticide exposure," he says. It doesn't appear to be tied to genetically engineered crops: Studies have shown such pollen fed to bees doesn't reduce their longevity, he says.
Honeybees are crucial for pollination-dependent crops, such as almonds, apples, blueberries, cranberries, pumpkins, watermelons and cucumbers, vanEngelsdorp says.