Understanding Honey Bee Immune System Crucial to Battling the Declining Honey Bee Population
May 26, 2011
Michelle Flenniken is the Häagen-Dazs Honey Bee Postdoctoral Scholar, UC Davis Department of Entomology, and an insect virologist in the Raul Andino lab, Department of Microbiology and Immunology at UC San Francisco. (Photo by Kim Fondrk)
DAVIS--Understanding the honey bee’s immune system is crucial to battling the declining honey bee population, says University of California insect virus researcher Michelle Flenniken.
Speaking to 100 fellow researchers at the Honey Bee Genomics and Biology Conference, held recently in the Cold Spring Harbor Laboratory, New York, Flenniken said that if a bee can develop better antiviral immune responses, it’s better able to fight its foes.
"Our work is focused on understanding the natural mechanisms of antiviral immunity in honey bees (or how a honey bees fights off viral infections),” she told the researchers. “We are examining these pathways at the molecular level using gene expression microarrays.”
Flenniken, the Häagen-Dazs Honey Bee Postdoctoral Scholar at UC Davis and a virologist in the Raul Andino lab, Department of Microbiology and Immunology at UC San Francisco, studies honey bee viruses and the role of RNA interference (RNAi) in the antiviral immune responses. RNA, or ribonucleic acid, carries genetic information of viruses. RNAi is a mechanism that inhibits gene expression.
RNAi can be used as an antiviral strategy in honey bees, Flenniken believes. Her research involves limiting virus production in the bees by priming their RNAi machinery with viral specific double-stranded RNA.
For the past several years, she has been analyzing viruses present in the hives of area beekeepers.
Her findings reported at the conference are mentioned in the May 10th edition of the international journal, Nature. Flenniken “presented evidence that in honey bees (double-stranded RNA) can trigger a general immune response that might ward off a variety of threats,” wrote Nature author Gwyneth Dickey Zakaib.
The geneticists first began meeting shortly after the honey bee genome was sequenced in March 2006. In November 2006, a Pennsylvania beekeeper who overwintered his bees in Florida announced the first report of CCD, a mysterious phenomenon characterized by adult bees abandoning the hives, leaving behind the queen bee and immature brood.
Since 2006 CCD has been a major factor in the decline of the honey bee population. It has remained at a fairly steady level since 2006, researchers day. Extension apiculturist Eric Mussen of the UC Davis Department of Entomology says CCD is probably due to a multitude of factors, including diseases, viruses, pests, pesticides, malnutrition, climate change and stress.
Total losses from bee colonies nationwide in the winter of 2010-2011 amounted to 30 percent from all causes for the 2010/2011 winter, according to the annual survey conducted by the U.S. Department of Agriculture (USDA) and the Apiary Inspectors of America and announced May 23.In comparison, losses in 2009-2010 totaled 34 percent; 2008-2009, 29 percent; 2007-2008, 36 percent, and 2006-2007, 32 percent.
"The lack of increase in losses is marginally encouraging in the sense that the problem does not appear to be getting worse for honey bees and beekeepers," said Jeff Pettis an entomologist with USDA's Agricultural Research Service who helped conduct the survey . "But continued losses of this size put tremendous pressure on the economic sustainability of commercial beekeeping." Pettis is the leader of the ARS Bee Research Laboratory, in Beltsville, Md., the chief scientific research agency of USDA.
Average colony loss for an individual beekeeper's operation was 38.4 percent, according to the ARS news release. This compares to an average loss of 42.2 percent for individual beekeepers' operations in 2009/2010.
“Among surveyed beekeepers who lost any colonies, 31 percent reported losing at least some of their colonies without finding dead bee bodies--one of the symptoms that defines CCD,” the ARS news release said. “As this was an interview-based survey, it was not possible to differentiate between verifiable cases of CCD and colonies lost as the result of other causes that share the ‘absence of dead bees’ as a symptom. The cause of CCD is still unknown.”
The beekeepers who reported colony losses with no dead bee bodies present also reported higher average colony losses (61 percent), compared to beekeepers who lost colonies but did not report the absence of dead bees (34 percent in losses).
A total of 5,572 beekeepers, who manage more than 15 percent of the country's estimated 2.68 million colonies, responded to the survey.
A complete analysis of the survey data will be published later this year.
--Kathy Keatley Garvey
UC Davis Department of Entomology