I have a much more simple view of the effect of smoke on bees.

It's "tear gas".

Bees have very sensitive odor-detection gear, and smoke simply
overloads their ability to smell anything but the smoke.  It seems to
irritate them, just as tear gas will "irritate" a crowd of protestors or
rioters.  Like protestors, the bees fall back, and try to get away
from the smoke.

To me, the slightly louder and changed  pitch of the "hum" of the colony
of the bees when they are smoked is clear proof that they are not happy
about being smoked.  The different sound is a prompt for me to cease
smoking the hive, and wait a minute to let the bees "adjust" before
working the hive.

Yes, the "load up on nectar" reaction is a reaction to smoke, but,
as Peter pointed out, bees will "load up on nectar" in reaction to a
wide array of different "disturbances".

That's why I always use smoke, but go easy on the smoke.
A little goes a long way.

        jim (Who, due to the economic slowdown, has abandoned
                  smoke and mirrors, and makes do with smoke alone)

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