A new threat to honey bees?

The domesticated honey bee’s life is anything but easy. Enslaved by humans to produce honey (for which their hives are regularly raided), uprooted to lead a nomadic life traveling on flatbed trucks from field to orchard, worked year-round, attacked by various mites, fungi and now exotic viruses, is it any wonder that some bees are collapsing from the sheer weight of it all?

honey bee with Apocephalus borealis larvae

Stricken honey bee with two emerging Apocephalus borealis (Diptera: Phoridae) emerging from the junction of its neck and thorax (from Andrew Core et. al 2011).

This accumulation of multiple stresses is, in fact, the current best guess by bee researchers on what is causing the much dreaded “colony collapse disorder”, or CCD.  Often cited as one of the signs of the apocalypse, along with global warming, catastophic oil spills, nuclear meltdowns and earthquakes, CCD is proof enough for many people that ecological disasters lurk around the next corner.

As if honey bees didn’t have a hard enough life, now comes a report from San Francisco State University about another possible emerging threat to honey bees.

Andrew Core and California colleagues published results this week in online journal PloS ONE about a tiny fly, Apocephalus borealis, found attacking honey bee colonies in the San Francisco area.  The fly, a relative of South American phorid flies that attack fire ants, had originally been recorded as a naturally-occurring parasite of bumble bees here in North America.  However the researchers note that, despite the fact that honey bees have been meticulously observed and studied over the years, no one has previously seen these phorid parasites attacking honey bees.

Like the fire ant-attacking phorids, these bee phorids pounce on foraging workers and deftly lay an egg in between the segments on the bee’s abdomen.  Within a week or two, fully developed wasp larvae can be found emerging from the neck of the deceased honey bee.  The study showed that before meeting their grisly end, infected bees would leave the hive at night and die outside of the colony.  Such behavior is also seen in bees affected by CCD, although the researchers do not believe that CCD and the phorid flies are related.

The fact that these parasites have never before been observed attacking honey bees lead the authors to conclude that this may be an example of a relatively new phenomenon, one that might be bad news to our increasingly beleaguered beekeepers (Note: In case you missed it here, these bee parasites are not the result of phorid flies imported for fire ant control.  The bee-attacking phorid fly species has apparently been here in North America for a long time, but the authors of this study theorize that, in a twist of evolutionary opportunism, this native fly has developed a new taste for honey bees in addition to bumble bees–their long-time prey.).

Amid all this bad news about honey bees, it’s important to know that, at least in Texas, wild honey bee populations appear to be in little danger of going away.  Honey bees have weathered many biological and human assaults in the past and will likely survive phorid flies too.  The ones to feel a little sorry for are our worried beekeepers and farmers who depend on strong bee colonies for a livelihood and who provide us with tasty nuts, fruit and honey.

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