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Monday, January 9th, 2012
Associated Press



IS ZOMBIE PARASITE CAUSING BEE DIE-OFF?
by GOSIA WOZNIACKA, Associated Press

In this photo provided by San Francisco State University, an Apocephalus borealis fly implants its eggs into the abdomen of a honey bee. The A. borealis fly is suspected of contributing to the decrease in the honey bee population. Researchers say the fly deposits its eggs in the abdomen of honey bees and as the larvae grow within the body of the bee, the bee begins to lose control of its ability to think and walk, flying blindly toward light. It eventually dies and the fly larvae emerge. (AP Photo/Christopher Quock, San Francisco State University)

FRESNO, Calif. (AP) - Northern California scientists say they have found a possible explanation for a honey bee die-off that has decimated hives around the world: A parasitic fly that hijacks the bees' bodies and causes them to abandon hives.


Scientists say the fly deposits its eggs into the bee's abdomen, causing the infected bee to exhibit zombie-like behavior by walking around in circles with no apparent sense of direction. The bee leaves the hive at night and dies shortly thereafter.


The symptoms mirror colony collapse disorder, in which all the adult honey bees in a colony suddenly disappear.


The disease is of great concern, because bees pollinate about a third of the United States' food supply. Its presence is especially alarming in California, the nation's top producer of fruits and vegetables, where bees play an essential role in the $2 billion almond industry and other crops.


The latest study, published Tuesday in the science journal PLoS ONE, points to the parasitic fly as the new threat to honey bees. It's another step in ongoing research to find the cause of the disease.


In this photo provided by San Francisco State University, the larvae of an Apocephalus borealis fly emerges from the dead body of a host honey bee. The A. borealis fly is suspected of contributing to the decrease in the honey bee population. Researchers say the fly deposits its eggs in the abdomen of honey bees and as the larvae grow within the body of the bee, the bee begins to lose control of its ability to think and walk, flying blindly toward light. It eventually dies and the fly larvae emerge. (AP Photo/John Hafernik, San Francisco State University)

Researchers haven't been able to pin down an exact cause of colony collapse or find a way to prevent it. Research so far points to a combination of factors including pesticide contamination, a lack of blooms - and hence nutrition - and mites, fungi, viruses and parasites.


Interaction among the parasite and multiple pathogens could be one possible factor in colony collapse, according to the latest study by researchers at San Francisco State University. It says the phorid fly, or apocephalus borealis, was found in bees from three-quarters of the 31 hives surveyed in the San Francisco Bay area.


The combination of a parasite, pathogens and other stressors could cause die-off, lead investigator John Hafernik said. The parasitic fly serves as a reservoir that harbors pathogens — honey bees from parasite-infected hives tested positive for deformed wing virus and other pathogens, the study found.


"We don't fully understand the web of interactions," Hafernik said. "The parasite could be another stressor, enough to push the bee over tipping point. Or it could play a primary role in causing the disease."


This photo provided by San Francisco State University shows the Apocephalus borealis fly. This fly is suspected of contributing to the decrease in the honey bee population. Researchers say the fly deposits its eggs in the abdomen of honey bees and as the larvae grow within the body of the bee, the bee begins to lose control of its ability to think and walk, flying blindly toward light. It eventually dies and the fly larvae emerge. (AP Photo/Jessica Van Den Berg, San Francisco State University)

Hafernik stumbled onto the parasitic fly by accident. Three years ago, the biology professor looked for something to feed a praying mantis. He found some bees outside his classroom, placed them in a vial and forgot about them. When he looked at the vial a week later, he found dead bees surrounded by small fly pupae. A parasitic fly was feeding on the bees and had killed them, he said.


The fly is a known parasite in bumble bees. Scientists used DNA barcoding to confirm the parasite in the honey bees and bumble bees was the same species.


The fly might have recently expanded its host presence from bumble bees to honey bees, Hafernik said, making it an emerging threat to agricultural pollinators. The fact that honey bees live in large colonies placed in close proximity to one another and beekeepers frequently move the hives throughout the country could lead to an explosion of the fly population, he said.


The fly, which is found all over North America, could also become a threat to native bees.

Hafernik plans to expand his research to other parts of the country and to study the parasite's impact on agriculture in California's Central Valley.


Since it was recognized in 2006, colony collapse has destroyed colonies at a rate of about 30 percent per year, according to the U.S. Department of Agriculture. Before that, losses were about 15 percent per year from a variety of pests and diseases.

 





Written by GOSIA WOZNIACKA, Associated Press
Copyright 2003 Associated Press. All rights reserved.This material may not be published, broadcast, rewritten , or redistributed.

Photos courtesy of AP Photo, San Francisco State University
Images created by Christopher Quock, John Hafernik, Jessica Van Den Berg
Last changed on: 1/9/2012

Wikipedia For more about Colony Collapse Disorder.

The MY HERO Project For the heroic story of Rachel Carson, the scientist who first warned of the ripple effects of pesticides on eco-systems.

 

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