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PULLMAN, Wash. — Recent research by scientists at Washington State University suggests two potential contributors to Colony Collapse Disorder (CCD), a mysterious malady that has slowly wiped out large numbers of bee hives throughout the United States in recent years, may be trace pesticides often found in old honeycombs and a new microscopic pathogen that has been quietly spreading throughout the Pacific Northwest and other regions of the country.
 
As the result of a project funded in part by regional beekeepers and the university’s Agricultural Research Center, WSU Entomology Professor Walter (Steve) Sheppard and his team believe they have successfully narrowed the potential list of colony collapse culprits.
 
“One of the first things we looked at was the pesticide levels in the wax of older honeycombs,” Sheppard said.

Using combs of CCD-affected colonies supplied by the U.S. Department of Agriculture, his group discovered many contained “fairly high levels of multiple pesticide residues.” Subsequent experiments showed that bees raised in those hives “had significantly reduced longevity,” Sheppard said.

The researchers noted that the types of trace chemicals found in the tested honeycombs included insecticides, herbicides, miticides and fungicides.
 
One easy method of addressing such chemical contamination is for beekeepers to change honeycombs more often, Sheppard said. In Europe, for example, apiarists change combs every three years.

“In the U.S., we haven’t emphasized this practice and there’s no real consensus about how often beekeepers should make the change,” he said. “Now we know that it needs to be more often.”
 
Another aspect of Sheppard’s work – being conducted by WSU graduate student Matthew Smart – focuses on the impact of a microsporidian pathogen known as Nosema ceranae, which attacks the bee’s ability to process food. Many beekeepers have considered it to be “the smoking gun” behind colony collapse.
 
“Nosema ceranae was only recently described in the U.S., the first time in 2007,” Sheppard said. “But while no one really noticed, it has spread throughout the country."
 
He said Smart surveyed numerous bee colonies in both the Pacific Northwest and in California, and found the new pathogen to be very widespread.
 
Sheppard’s earlier research found the pathogen to be a tough bug to battle. Of 24 hives checked in early 2008, Nosema build-up was high in a majority of the bees sampled. Beekeeper Eric Olson of Yakima, Wash. said he treated his hives with a mega-dose of the antibiotic fumagillin, but was surprised by the results.

“That should have caused the Nosema to either disappear or at least go down,” Olson said. “But instead, the levels went up.”

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