Hello Deborah
 
I am a beekeeper in the UK who is a member of a research group that
have been studying some of the questions that you have asked.  Of
course my viewpoint is from the UK,  but most will be relevant to the
US.
 
> I am a UW Madison graduate student developing a story about bedding down
> varroa decimated beehives for the winter, progress in coping with the
> infestation and prognostications for the year to come.
 
> How serious is the threat of mite infestation to honeybees and honey
> production in the United States?
 
Serious but maybe not as serious as some would suggest.  European
countries have suffered with Varroa for decades!  So their experience
is the best guide to what will happen in the US.
 
Probably -
 
- Initial panic amongst beekeepers
 
- The development of real experiences of infestation and the knowledge
of the infestation and how to treat it.
 
- Scare stories in the press!!
 
- The loss of many feral colonies and high colony loss by many
beekeepers
 
- 'Let alone' beekeepers no longer have bees to keep
 
- Stories appear about lack of pollination in vulnerable crops
 
- Beekeepers begin to learn how to live with Varroa
 
- Reduced losses due to Varroa.
 
> How would you describe the econonomic impact of the infestation in this
> country?
 
I don't know about the US,  which relies more on the use of
beekeepers moving bees for pollination than most parts of Europe.
Beekeepers will be able to provide these colonies (after initial
losses),  but with the loss of feral bees this will be more
important.  I would expect the cost of pollination to rise and therby
slightly increase the cost of those foodstuffs.
 
Eventually (not for many decades) Varroa tolerant bees.
 
> What do the mites do that kills bees? What more familiar process might it
> be compared to?
 
This is still poorly understood,  Varroa feed on larval haemolymph
and it has been thought that it is this does the damage.  But new
work is showing that in fact bees can tolerate very high infestations
and what kills bees are the viruses that are already present within
the bee population (or maybe transmitted by Varroa).  Varroa inject
proteins when they feed (anti-coagulants etc.) it is now thought that
this causes the viral level of bees to rise greatly,  overcoming the
bees resistance to disease.  It seems to bre the experience of areas
that become infested with Varroa that after subsequent high losses
the losses decrease rapidly,  this is probably due to the fact that
the disease resistant bees remain and the less resistant ones have
been eradicated.
 
> I would also appreciate some framework information:
 
You'll have to be more explicit!  I can point you in the direction of
a book about Varroa if you are interested
 
I can also tell you how to search the Bee-l Listserv for all messages
containing the word 'Varroa'  if you're feeling really keen!
 
> How many bees inhabit how many humanmade hives in the US? How does that
> compare to the past 1-5 years? 5-10 years?
 
Don't know
 
> For the same intervals, how much honey have they produced comparatively?
 
Somebody posted information on this recently,  you may have to ask
the list again with that specific question
 
> For the same intervals, how many acres or sq. miles do they pollinate
> comparatively?
 
Don't know
 
> What crops do bees pollinate? Do any other species contribute to this
> pollination? (butterflies, hummingbirds, etc.) If so, in what proportion?
> If not, what alternatives, if any exist?
 
This is a US specific question to which an answer could easily be
found I'm sure.  Any list would include -
 
Beans
Blueberries
Apples/Pears
Citrus
Plum family
Cherries
Oil Seed Rape (you have another name for this in the US -= but I know
its a commonly used cooking oil)
 
and many many other crops/plants/trees
 
> I have heard that 60% to 80% of honeybees were lost last winter, compared
> to normal annual loss of 5-6%. Is this accurate?
 
I suspect this may be an exaggeration,  but I don't know US figures,
although SOME areas may have had these losses.
 
 
Best wishes
 
Joe Hemmens