Colony Collapse May Be Associated With Viral, Fungal Infection

Scientists have discovered a possible cause of the recurring death of bee colonies since 2006 — a combination of viral and fungal factors.
From Texas Tech University
October 8, 2010
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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 billions.

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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, says 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 billions.

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 says. “Our contribution to this study confirms association. But even that doesn’t prove cause and effect. Not just yet.”

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

To discover what may 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 says. 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 says.

Bilimoria says 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 whether 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 the same virus and fungus,” Bilimoria says.

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 says. “It is easier to fight the problem if we know what the culprit is.”

While reports have claimed a tag-teaming of viral and fungal problems as a leading concern in honeybee death, it turns out that some data may have been misinterpreted. Pesticides, as well as other diseases, may also be playing a large role in colony collapse disorder, as discussed in Honeybee Mystery Solved? Not Quite, Bee Experts Say. To read more on the decline of the honeybee population and colony collapse disorder, visit our Honeybee Decline page.  — MOTHER 

Post a comment below.


1/3/2011 11:11:31 AM in the words of the epa: "Clothianidin’s major risk concern is to nontarget insects (that is, honey bees).Clothianidin is a neonicotinoid insecticide that is both persistent and systemic. Acute toxicity studies to honey bees show that clothianidin is highly toxic on both a contact and an oral basis." The EPA approved what France, Slovenia, Germany, Italy banned. These countries know neonicotinoids kill bees. Seeds coated with this class of pesticide exude the chemical in the plant's nectar and pollen ...and poison bees.

t brandt
11/7/2010 5:11:38 AM
Thanks for bringing some sensible science to this topic which has been plagued by so many emotional fantasies from the partially educated. It seems that bee populatons do fluctuate drastically on decadal time scales and this may well be due to a dynamic interaction with disease species. The recent CCD episode is just part of that natural history. We must also keep in mind that honey bees, afterall, are an exotic species. Their presence in NA is artificial and they displace natural pollinating species here, an no food crop absolutely "depends" on the honey bee.

10/16/2010 10:03:09 AM
It seems a perfect storm with these two enemies plus our own engineering the seeds to be more resistant of bugs. The nectar from these plants probably kills bees at an alarming rate, this study would make more sense than the flow rate of ketchup!! Stop these systemic changes now before all the bees are gone...

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