Did a parasitic fly cause Colony Collapse in bees?

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Apocephalus lays eggs in the abdomen of a honey bee. photo: C. Quock.

The science media is buzzing (ha, ha) with tales of a new honey bee parasite, Apocephalus borealis, and its potential involvement in Colony Collapse. For example:

Parasitic flies that turn honeybees into night-flying zombies could provide another clue to cracking the mystery of colony collapse disorder.

Since 2007, thousands of hives in the US have been decimated as bees inexplicably go missing overnight. The best explanation so far is that multiple stresses, perhaps parasitic mites, viruses or pesticides, combine to tip the bees over the edge.

John Hafernik of San Francisco State University in California and colleagues discovered that hosting Apocephalus borealis, a parasitic fly found throughout North America, makes bees fly around in a disoriented way at night, when they normally roost in the hive, before killing them.

-(excerpted from New Scientist)

The research appeared this afternoon in PloS One. In it, researchers springboarded from an entirely accidental discovery of flies emerging from bee carcasses to demonstrate that:

  1. The flies are new to honey bees, and are a native species previously known to attack bumble bees.
  2. Parasitized bees abandon their hives.
  3. Hives attacked by flies show elevated rates of infection by CCD-associated pathogens.
  4. Parasitism rates peak at the same time of year as CCD.

Is Apocephalus the missing piece to the CCD puzzle? I think that conclusion is premature.

The study shows, in one region of the country, a parasite that can replicate one of the symptoms of colony collapse. That’s it. A correlation. The link with other CCD-associated pathogens doesn’t mean terribly much, as pathogens often flourish as a sick patient’s immune system weakens. The geography of Apis-attacking Apocephalus borealis has not yet been shown to coincide with regions of Colony Collapse. Nor is there evidence that healthy hives collapse when subjected to phorid attack- with or without the other CCD-related pathogens. Perhaps such evidence will come, but for now it is best to view the CCD implications of this study conservatively. It’s a suggestion.

I am not being harsh on the science itself. A novel and potentially damaging honey bee pest is Big News, and Core et al is as fine a study on a host-shifting parasite as they come. Rather, I am merely questioning the heavy framing around CCD. I know there’s research dollars in them thar hills, but let’s not get ahead of ourselves.


source: Core A, Runckel C, Ivers J, Quock C, Siapno T, et al. (2012) A New Threat to Honey Bees, the Parasitic Phorid Fly Apocephalus borealis. PLoS ONE 7(1): e29639. doi:10.1371/journal.pone.0029639

14 thoughts on “Did a parasitic fly cause Colony Collapse in bees?”

  1. Alex,
    You would make a terrible ecologist. Jumping to conclusions that also happen to make for a “nice story” on the basis of correlations is a key skill that all ecologists must develop. Oh well, I’m sure you’ll figure out some other career path.

    1. touche

      modern science at it’s most pseudo…..don’t forget all the other applicable branches of inquiry eg AGW, subatomic particle theory, human anthropology, dark matter, etc. LOL

  2. It seems like this is a question that citizen science might help answer. If I see any disoriented honey bees near lights at night, I’m going to collect them and see if a parasite emerges.

    1. Christopher D. Smith

      Please do! If critters emerge send them to John Hafernik at SFSU and we can barcode them to show it is the same species.

      1. I have been frantic to find ALL I could on A.borealis, because while pruning a very sick nectarine tree, I felt repeatative “pin-stabbings on the back of my exposed calves, twice I slapped at the prolonged “pricking” sites, and drew back fingers with a wet yellowish brown-striped “ick”, (very tiny, but, looking closely, I could SEE they were the same consistency, colors, pattern, and size, and,intrigued, I determined to gently “pinch-remove” the pest carefully enough to be able to SEE what was pricking my legs!! Again!! I pinched it VERY GENTLY and held it pressed between my thumb and first finger for a bout a minute as I made my way to inside my kitchen and to a blank piece of paper and a magnification glass!! My mind was racing!! How did I manage to actually KILL 2 of these ??? AND SIMPLY PICK THE THIRD OFF MY SKIN?? BECAUSE IT WAS ENGAGED IN MY SKIN!!! It was KEEPING IT’S “STINGER” IN!!! WHYYY!!???? I saved it in a “zip-lock baggie”– and began an internet search to find out WHAT it was’
        It had a black eye, yellowish head&body, with light brown stripes,clear wings with a light grey single spot at the end of each wing, and seemed about 1/8″ long!! It took more than a few days to find A. borealis, with
        –NOT A STINGER, BUT AN OVIPOSITOR!!!!!!!!!! It may have been OVIPOSITING AN EGG INTO MY LEGS!!!!
        Think about how tiny this”fly” is. Think about how TINY her egg IS!!! Could it travel to my BRAIN??!!! WHAT WOULD IT DO TO MY BRAIN AS IT GREW?!!!! WERE THESE ” STINGS”
        A MULTIPLE INVASION??!! (I was “stung” more than 4 times before I caught the last one!!) I hope I’m wrong, but this may be a more serious problem than we already FEAR!!!

  3. It certainly makes for an interesting story and one that sounds more feasible than some that have been proposed for CCD. [like mentioned cell phones]

    Moving millions of hives around the world can not be helping with disease and parasite epidemiology to say the least.

    So much to learn and so little time and effort to learn it….

  4. Christopher D. Smith

    I’d like to note that the authors never conclude that the phorid is a cause of colony collapse. This is a conflation the press has made. We claim that the hive abandonment behavior seen in phorid-infected bees is reminiscent of a defining phenotype of CCD. Indeed, no phorid-infected hives from the study ‘collapsed’. The study is simply meant to describe a novel parasitoid and possible host jump and draw attention to the hive abandonment. It is our hope that citizen scientists can, indeed, help by helping to find more cases of phorid infected bees outside of the Western region.

    And I respectfully would also like to suggest that framing the story in terms of CCD is not a vulgar chase after dwindling grant dollars given USDA cuts. It helps to communicate in terms a phenomena that better publicized. While phorids are almost certainly not the cause of CCD, they are yet another insult potentially exacerbating this poorly understood syndrome. My personal hypothesis is that the dramatic insult of a phorid eating the innards of a bee may ‘phenocopy’ the same abandonment that multiple agents do for ‘normal’ CCD.

  5. I have been frantic to find ALL I could on A.borealis, because while pruning a very sick nectarine tree, I felt repeatative “pin-stabbings on the back of my exposed calves, twice I slapped at the prolonged “pricking” sites, and drew back fingers with a wet yellowish brown-striped “ick”, (very tiny, but, looking closely, I could SEE they were the same consistency, colors, pattern, and size, and,intrigued, I determined to gently “pinch-remove” the pest carefully enough to be able to SEE what was pricking my legs!! Again!! I pinched it VERY GENTLY and held it pressed between my thumb and first finger for a bout a minute as I made my way to inside my kitchen and to a blank piece of paper and a magnification glass!! My mind was racing!! How did I manage to actually KILL 2 of these ??? AND SIMPLY PICK THE THIRD OFF MY SKIN?? BECAUSE IT WAS ENGAGED IN MY SKIN!!! It was KEEPING IT’S “STINGER” IN!!! WHYYY!!???? I saved it in a “zip-lock baggie”– and began an internet search to find out WHAT it was’
    It had a black eye, yellowish head&body, with light brown stripes,clear wings with a light grey single spot at the end of each wing, and seemed about 1/8″ long!! It took more than a few days to find A. borealis, with
    –NOT A STINGER, BUT AN OVIPOSITOR!!!!!!!!!! It may have been OVIPOSITING AN EGG INTO MY LEGS!!!!
    Think about how tiny this”fly” is. Think about how TINY her egg IS!!! Could it travel to my BRAIN??!!! WHAT WOULD IT DO TO MY BRAIN AS IT GREW?!!!! WERE THESE ” STINGS” pp
    A MULTIPLE INVASION??!! (I was “stung” more than 4 times before I caught the last one!!) I hope I’m wrong, but this may be a more serious problem than we already FEAR!!!

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