An Answer to the Mysterious Honeybee Die-Off

Scientists think they’re closer to figuring out what’s causing the mysterious mass die-off of honeybees.

The New York Times tells the story of a unique collaboration of academia and Army scientists who found the presence of two biological menaces in all 40 hives they studied — one a fungus, the other a virus.

The findings shed light on “colony collapse disorder,” which has baffled scientists and decimated about a third of the nation’s honeybee hives since 2006. Bees are important: Some 85 commercial crops, from almonds to avocados, need pollination by the fuzzy fliers to yield harvests.

The coalition recently published its findings in the journal Public Library of Science One.

Researchers at the University of Montana combined their entomology expertise with Edgewood Chemical Biological Center’s high-tech software designed to identify biological agents that could harm Army soldiers. By using another not-so-high-tech tool — a coffee grinder used to mash up honeybees — scientists uncovered a new DNA-based virus in the bees and established it works in tandem with a previously known fungus called Nosema ceranae.

Viruses and fungi have long been suspected to threaten honeybees, along with mites and pesticides.

I wrote about a University of San Diego, California team late last year that is also studying colony collapse.

After reading The Times story, I spoke with principal investigator James Nieh. He said the new findings fill in one piece of the puzzle.

“There is no single cause that we can say ‘OK we’ve nailed it, this is the cause of colony collapse. We don’t have to worry about anything else.’ I don’t think we have that answer yet,” Nieh said.

While significant, the study doesn’t explain the eerily abandoned hives, which Nieh likens to a boat in the ocean with no sign of evacuees or a visible disturbance.

Nieh believes pesticides and insecticides are also degrading honeybee health.

Pesticides can disorient bees, according to Nieh’s research. He and graduate student Daren Eiri found bees that drank a pesticide-laced tincture couldn’t find their way back to a chosen destination — which hints at why collapsed hives are turning up virtually empty, with little trace of the disappeared foragers.

“They never get to the food. So they can run out of fuel. They can simply die,” Nieh said. “If you go out in the morning and find a bee laying on your driveway or your car, chances are the bee was trying to get food but didn’t find it and didn’t have enough fuel to make it back.”

The UCSD Nieh Bee Lab also found that low doses of the insecticide Imidacloprid affect the honeybee palate. Treated insects only opt for super sweet liquid, while many natural flowers and plants produce a less sugary nectar.

Nieh would like to see studies on whether viruses and fungi make bees more sensitive to pesticides. He believes multiple causes are killing honeybees, already stressed by a human-imposed lifestyle of commercial pollination.

Update: Check out this Fortune magazine story for more on the pesticide angle, including questions over whether the lead scientist in the NYT article has a conflict of interest.

Please contact Rebecca Tolin directly at rebeccatolin@yahoo.com.