>
> >To reiterate, once nighttime temps. are low enough to cause clustering,
> even with still available pollen my bees will shut down brood rearing but
> continue to hoard pollen for the following spring as long as they have good
> flying conditions and natural pollen available.


Exactly what my colonies are currently doing in California.

Jose, I've discussed Al Avitabile's findings with him, and he did not feel
that he had good evidence supporting an effect of daylength.

Re Kefuss's paper, I suggest that you look very carefully at his graphs.
His conclusions are below:

"The two experiments show that brood can be reared under both long-day and
short-day conditions, indicating that a critical day length does not need
to be crossed for brood rearing to occur. The distinct trend shown by these
experiments is that brood rearing increases while the photoperiod is
increasing and decreases while the photoperiod is decreasing, regardless of
the actual length of photoperiod. A photoperiod can be either
brood-stimulating or brood-inhibiting, depending upon the direction in
which it is changing. Thus the brood-rearing cycle of the honeybee cannot
be a simple reaction to day length in which brood rearing starts or stops
after a critical photoperiod has been reached. "

And even the above "trends" were pretty iffy.

I've looked into this for some time, and the best that I can interpret the
observations and experimental data is that broodrearing has more to do with
temperature and pollen availability than anything else.  Changes in
daylength, but not absolute daylength also appears to be a contributing
factor.  One thing that I'm still not clear on is the stimulus for winter
broodrearing, which appears to occur even in light-free,
constant-temperature sheds (can any of you Canadians confirm this?).


-- 
Randy Oliver
Grass Valley, CA
www.ScientificBeekeeping.com

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