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