Not every dead bee is colony collapse disorder

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The media is buzzing this morning with the nth edition of What’s-Been-Killing-The-Bees:

…the mysterious mass die-off of honey bees that pollinate $30 billion worth of crops in the US has so decimated America’s Apis mellifera population that one bad winter could leave fields fallow. Now, a new study has pinpointed some of the probable causes of bee deaths and the rather scary results show that averting beemageddon will be much more difficult than previously thought.

Ever since Colony Collapse Disorder surfaced in late 2006, we’ve been treated to story after story proclaiming that scientists have finally discovered the cause: pesticides, viruses, cell phones, parasitic flies, fungi, mites, GMOs. Each story has the same formula. A study documents cause X killing bees, the media runs X as causing CCD, and the activist community amplifies the connection with increasingly alarming rhetoric.

The trouble is a simple logical fallacy. X kills bees, and CCD kills bees, but that doesn’t mean that X = CCD. After all, cigarettes kill people, but not all people die from cigarettes. To bring any of these causes full circle requires not only establishing that X can replicate CCD symptoms- that’s the easy bit- but that X was present in documented CCD cases and that experimental treatment of bees with X leads to CCD. Anything short of that, however interesting, is hypothesis rather than fact.

As you might imagine, beekeepers themselves have become rather cynical about any science on CCD. After being burned, say, five or ten times, can you blame them?

Keeping in mind an appropriate level of caution, though, the most recent study in the mix is a good one. Writing in PLoS One, Pettis et al document a shocking quantity and diversity of pesticides gathered by honey bees in real agricultural settings. When they fed the most abundant of these- a fungicide- back to the bees at realistic doses, they found affected bees were more susceptible to the parasite Nosema ceranae. This observation is intriguing, as Nosema ceranae infections are known to kill foraging bees away from the hive, one of the signatures of colony collapse. Not only that, but Nosema ceranae is also a recent import to our continent, potentially explaining the sudden appearance of CCD.

As a cause of colony collapse, though, the science behind the pesticide/pathogen double whammy isn’t quite there yet. To move beyond a promising hypothesis, bee researchers must still document the presence of the relevant pesticides and pathogens in collapsed hives, and then re-create collapse at the colony level in field experiments. We owe it to the bees, and the beekeepers, to do the science right.


source: Pettis JS, Lichtenberg EM, Andree M, Stitzinger J, Rose R, et al. (2013) Crop Pollination Exposes Honey Bees to Pesticides Which Alters Their Susceptibility to the Gut Pathogen Nosema ceranae. PLoS ONE 8(7): e70182. doi:10.1371/journal.pone.0070182

11 thoughts on “Not every dead bee is colony collapse disorder”

      1. The parasitic fly I’ve noticed in my hives for about 10 years now. There more now than ever before. I’ve also noticed small cocoons in hives I’ve lost( along with cocoons from wax mouth and hive beetle. You don’t hear a lot about small hive beetle and it’s a big problem down here in the deep south. You also don’t here anything about the parasitic fly. The researcher should keep their own hives and if they do they need to be more observant. A blind man could see these problems. It’s been my experience that no one will listen to a beekeeper unless he’s a researcher or with the department of agriculture. Us lonely beekeepers with 25 or less hives don’t know anything! I tell you what, because we only have a few hive we have more time for each hive and more time to notice things. Were the one’s they should be talking to and listening to!!!

  1. Why do you have to do the circle-jerk? There is more than enough evidence that pesticides are responsible for the majority of the CCD, so why not ban the pesticides? It’s logical, and Europe is already doing it – BECAUSE IT IS IMPORTANT!!!!

    1. I am applying to CCD the same logical standards used to determine the causes of human diseases: http://en.wikipedia.org/wiki/Koch's_postulates

      Since the putative agents of CCD have not yet been through the appropriate tests, it remains premature to know if correlations are spurious, or even if the correct agents have been identified. Plus, if we accept the results from this most recent paper, Europe has banned the wrong pesticide.

      Throwing insults does not amount to much of anything. Sorry.

    2. I think it would be pretty difficult to just ‘ban the pesticides’. Even if some culprits are identified, there will be powerful lobbying from the industries that make them, and strong resistance from farmers who think they need them.

  2. Look no further than varroa mites. Santa Cruz Island off the coast of California had so many honey bees that their buzzing pervaded the island. The introduction of 85 (that’s right, just 85) varroa mites completely eliminated every single honey bee on the island. And bear in mind that these were healthy colonies that had been isolated from the pathogens, parasites, pesticides, and stresses to which mainland colonies are subjected for over 100 years.

    Varroa mites are the only putative cause of honey bee colony collapse disorder (CCD) to have passed the third prong of your 3-prong test of CCD: experimental treatment of bees with X leads to CCD. See the articles below for the experiment where X (the varroa mite) was introduced into a population of at least 117 feral honey bee colonies and every colony collapsed. And all without the confounding effects of other pathogens, parasites, or pesticides.

    Wenner, M.A., R.W. Thorp, and J.F. Barthell. 2000. Removal of European Honey Bees from the Santa Cruz Island Ecosystem. Pages 256–268. In: D.R. Browne, K.L. Mitchell, and H.W.
    Chaney ( eds.) , Fi fth Cali forni a Islands Symposium. MBC Applied Environmental Sciences, Costa Mesa, CA.
    http://www.mednscience.org/sites/default/files/products/Wenner_European_Bee_Removal_SCI.pdf

    Wenner, M.A., R.W. Thorp, and J.F. Barthell. 2009. Biological Control and Eradication of Feral Honey Bee Colonies on Santa Cruz Island, California: A Summary. Pages 327–335. In: Damiani, C.C. and D.K. Garcelon (eds.). Proceedings of the 7th California Islands Symposium. Institute for Wildlife Studies, Arcata, CA.
    http://iws.org/CISProceedings/7th_CIS_Proceedings/Wenner.pdf

  3. Thanks for the article – there is no substitute for solid, hypothesis based research, some of which seems to be pretty scarce.

    However what concerns me more, is that all the lobbying to keep pesticides seems to ignore the possibility that you might be damaging the very thing on which you depend for your crops – pollinating insects. Cutting off your nose to spite your face?

    Having said this, here in Europe a cold and damp winter had a devastating effect on a lot of hives – not sure as yet if there is a lot of data on climate effects?

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