Virus research sheds light on colony woes
New study expands knowledge of disease cycle in beehives
By TIM HEARDEN
SAN FRANCISCO -- Scientists here believe they can get a foothold on colony collapse disorder as a result of a 10-month study of viruses that affect normal hives.
University of California-San Francisco researchers identified four new viruses that affect honeybees, while discovering that each of the viruses or bacteria previously linked to the disorder were also present in healthy hives.
The discoveries give scientists a "baseline" with which to compare healthy hives with those from which bees have disappeared, they say.
"In my own opinion, our research opens new doors of investigation into CCD," said lead researcher Joe DeRisi, a Howard Hughes Medical Institute investigator and biochemistry and biophysics professor at UCSF.
"The whole reason we initiated this study was that there was an obviously incomplete understanding of the pathogens that affect honeybees," DeRisi said. "Before CCD, investigating pathogens in honeybees was not a very large interest because there wasn't a lot of reason to do it. With CCD it was kind of a wake-up call."
Results from the study, which tracked 20 colonies in a commercial beekeeping operation of more than 70,000 hives, are reported in the June 7 issue of the Public Library of Science ONE, known as PLoS ONE.
The results depict a distinct pattern of infections through the seasons and provide a normal baseline for researchers studying a colony that has collapsed, according to a UCSF news release.
The study tracked 27 unique viruses that afflict honeybees, including four that were previously unknown and others proposed as causes of colony collapse, the release stated. In addition, researchers identified six species each of bacteria and fungi, four types of mites and a parasitic fly called a phorid, which hadn't been seen in bees outside California.
One of the new viruses, a strain of the Lake Sinai virus, turned out to be the primary element of the honeybee biome, or community of bacteria and viruses, the release stated.
"We initiated this research in order to better understand the full scope of pathogens that are potential or emerging threats to honeybee populations," DeRisi said.
"I think we really set the stage in a very comprehensive way to make ongoing and future studies that will be much more accurate, much more precise and much more comprehensive," he said.
Honeybees each year pollinate 130 crops valued at more than $15 billion, representing about a third of the human diet, according to UCSF statistics. For the California almond crop to be successfully pollinated, about half the nation's honeybees -- about 1.3 million colonies -- must be in the Central Valley by the first week of February, DeRisi said.
The research comes as a USDA study found the national die-off rate for honeybee colonies from all causes was 30 percent last winter, down slightly from the 32 percent of bees lost in the winter of 2009-10.
Temporal Analysis of the Honey Bee Microbiome Reveals Four Novel Viruses and Seasonal Prevalence of Known Viruses, Nosema, and Crithidia: http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0020656