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Bee-Killing Parasite's Genome Sequenced

June 5, 2009

Agricultural Research Service (ARS) scientists have sequenced the genome of an invasive parasite called Nosema ceranae that can kill honey bees and is one of the many suspects in the mysterious ailment known as colony collapse disorder (CCD).

ARS researchers Jay Evans, Yanping (Judy) Chen and R. Scott Cornman also have nearly completed sequencing the genome of Nosema apis, a native "cousin" of the parasite.

The scientists are using genetic tools and microscopic analysis at the ARS Bee Research Laboratory (BRL) in Beltsville, Md., to examine the two parasites suspected as a partial cause of CCD. They are working with BRL research leader Jeff Pettis, Yan Zhao of the ARS Molecular Plant Pathology Laboratory in Beltsville, and researchers from the University of Maryland, Columbia University, and 454 Life Sciences of Branford, Conn.

In 2006, CCD began devastating commercial beekeeping operations, with some beekeepers reporting losses of up to 90 percent. Researchers believe CCD may be the result of a combination of pathogens, parasites and stress factors, but the cause remains elusive. At stake are honey bees that add up to $15 billion in value to crops in the United States.

Nosema is a fungus-related microbe that produces spores that bees consume when they forage. Infection spreads from the bees' digestive tract to other tissues. Within weeks, colonies are either wiped out or lose much of their strength. N. apis was the leading cause of microsporidia infections among domestic bee colonies until recently, when N. ceranae jumped from Asian honey bees to the European honey bees used commercially in the United States.

Sequencing the genomes should help scientists figure out how N. ceranae became dominant, trace its migration patterns, help resolve how the microbes spread infection, and develop diagnostic tests and treatments. A report on the work was recently published in the journal PLOS Pathogens.

ARS is the principal intramural scientific research agency in the U.S. Department of Agriculture.