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Bee colony collapse associated with viral, fungal infection

The sudden death of bee
colonies since late 2006 across North America has stumped scientists. But
today, researchers may have a greater understanding of the mysterious colony
collapse disorder, said a Texas Tech University biologist.

Shan Bilimoria, a professor
and molecular virologist, said the bees may be taking a one-two punch from both
an insect virus and a fungus, which may be causing bees to die off by the

Bilimoria is part of a team
of researchers searching for the cause of the collapse. Led by research
professor Jerry Bromenshenk from the University of Montana in Missoula, the
group also includes virologists and chemists from the U.S. Army Edgewood
Chemical Biological Center and the Instituto de Ecologica AC in Mexico.

Their study was published
this week in the peer-reviewed journal PLoS ONE. 

"At this stage, the
study is showing an association of death rates of the bees with the virus and
fungus present," Bilimoria said. "Our contribution to this study
confirms association. But even that doesn't prove cause and effect. Not just

The mysterious colony deaths
have caused major concern with scientists since much of agriculture depends on
bees to pollinate crops.

To discover what might be
attacking bee colonies, the team ground up dead bees that had succumbed to
colony collapse disorder. Using analytical equipment, researchers discovered
through spectroscopic analysis evidence of a moth virus called insect
iridescent virus (IIV) 6 and a fungal parasite called Nosema.

The insect virus is closely
related to another virus that wiped out bee populations 20 years ago in India,
he said. Also, unlike previous research that found the deaths may be caused by
a virus with RNA, the IIV 6 contains DNA.

"Our DNA discovery puts
this field in a whole new direction," he said.

Bilimoria said Texas Tech
supplied the virus material for the experiments and were tested on bees with
the fungus. Though an association between exposure and death was found,
scientists don't yet know if the two pathogens cause CCD or whether CCD
colonies are more likely to succumb to the two pathogens. 

"To prove cause and effect,
we will have to isolate the virus and fungus from bee colony, and then reinfect
with same virus and fungus," Bilimoria said.

In the next part of the
research project, Bilimoria will work to isolate the virus from infected bees.

"Once we isolate and
identify the virus, we will have a way of monitoring it," he said.
"It is easier to fight the problem if we know what the culprit is."

By John Davis, Texas Tech

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