PLB responds to Debbee Corcoran, who attended the recent SABA meeting
(so did I), and refers to Samuel Ramsey's excellent presentation,
which made the point that:

>> the varroa mite feeds not on the bee's haemolymph but on their
>> fat bodies.

> I am not sure why people think this has to be one or the other.  [...]
> Fat bodies are in the hemolymph, so if the varroa is sucking on a 
> bee pupa, she's getting a mouth full of hemolymph and fat.

Fair enough, but it seems that many studies which correlate varroa
parasitism with bee mortality end with something to the effect of "but
it's not clear why the removal of a small amount of hemolymph would
have this effect".  I didn't take notes, but from memory: it seems
that the fat bodies are strongly involved in the bee's immune system
(hence the greatly increased susceptibility to viruses), with
metamorphosis and longevity (hence the reduced lifespan of winter bees
when varroa levels are not controlled in August), and with several
other important functions that escape my memory right now.

Based on soon-to-be-Dr. Ramsey's studies, it turns out that varroa are
not closely related to blood-feeding insects, but rather to insects
that use extra-oral digestion (injecting digestive fluids into their
host to break down the tissues, and then eating/drinking those tissues).

I trust that this work will soon be available in print, if it isn't
already.  Meanwhile, if someone decides to chew up my liver, their
also getting a few ml of blood may be a fact, but perhaps not an
important one, all things considered.  ;-)


Anne, backyard beekeeper, Montreal.

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