Colony Collapse Disorder: Is a virus causing bees to disappear?

My daughter, who is only 4 and has been stung twice, would probably be happy to see all bees disappear.  But bees are important pollinators and we depend on them for many crops.  A very puzzling disorder has been causing bee colonies to collapse in North America: hives that still have abundant resources become abandoned.  The bees disappear and die.  This is odd because, if there were some infectious disease killing the bees you might expect to find lots of dead bees in the hive.  But they seem to just disappear.

Many studies have been done to try to identify the culprit.  Israeli accute paralysis virus, Varoa destructor virus -1, and the fungus Nosema ceranae have all been implicated but eventually ruled out because their presence was not strongly correlated with colony collapse disorder.  A new culprit has been proposed now: a co-infection by the fungus Nosema and a large DNA virus of the family Iridoviridae called Invertebrate Iridescent Virus (IIV).

In a recent post I described the use of metagenomics to sequence all the nucleic acids present in a sample to find the cause of acute flaccid paralysis in South Asia.  Metagenomics had been tried here and failed to identify the true culprit.  In this study they used a different approach called proteomics.  They sequenced protein fragments, rather than nucleic acids, from both healthy and collapsing bee colonies to try to find specific proteins associated with CCD.  What was found were proteins from Nosema and IIV.

There is a strong correlation between the co-infection and CCD, and they went on t show that the co-infection does indeed kill bees.  There are still many unknowns, however.  What is it about the interaction between these two pathogens that results in this odd disorder?  What makes the bees fly away and die rather than die in the hive?  Are they getting lost and confused?  How is it spread and how can we stop it?

(You can also check out the article in the NY TImes).


One thought on “Colony Collapse Disorder: Is a virus causing bees to disappear?”

  1. I normally thought that the bees left due to the change in temperature. When cold weather came, they left. Some possibly would make there ways into warm homes during cold weather. The interaction of the two pathogens results in the disorder IIV which may be a cause for the bees to die off. Bees in dying colonies contain not only IIV, but also Nosema. Co-occurrence of the nosema and iridoviridae microbes have consistently marked colony collapse disorder.
    According to studies, RNA fragments in the gut of bees from the CCD colonies may be markers of CCD. Mass spectrometry-based proteomics (MSP) and a sampling method were used in attempt to identify markers of CCD. Mass spectrometry yielded unambiguous peptide fragment data. Peptide fragment data acquired by MSP allowed identification and classification of microorganisms from the environment that was unrestricted by the need for primers. This allowed for detection and classification of fungi and viruses. The MSP analyses revealed the presence of two RNA viruses not previously reported in North American bee populations, as well as a highly significant and also unreported co-occurrence of strains of DNA IIV with a microsporidian of Nosema in CCD colonies. The two RNA viruses were only seen occasionally, but the finding of the DNA virus in nearly all CCD samples established a new take on CCD research, because nearly all previous viral work to date in honey bees focused on RNA viruses.

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