Perhaps it's not clear to all that bees normally have free choice in
deciding the protein to carbohydrate ratio in their diet--the protein
source being pollen and the carbohydrate source being nectar or honey.
They've had millions of years practice in learning how to balance their
diet to optimum.

I suggest that readers take a look into their hives in early spring.  In my
area, the nurses are often consuming every bit of incoming pollen, with
zero reserve remaining as beebread by the next morning.  This observation
strongly implies that protein at that time would be the limiting nutrient
for colony growth, and that any reduction in the protein content of the
pollen would prevent the colony from growing optimally.

After reviewing the zinc content of pollens worldwide, as well as the
experimentally-determined optimal zinc level in the bee diet, I also
suspect that the reduction in zinc due to elevated CO2 levels may be making
zinc the limiting nutrient in some areas.

As far as bees going into winter, I've compared notes with a number of
large-scale almond pollinators who consistently bring the strongest hives
to almonds.  One common element is that they ensure that their colonies get
plentiful late-season protein, either from high-quality natural pollen, or
from the generous feeding of a high-quality pollen sub.  In my own
operation, in which late-season pollen is very limited, and sometimes of
low quality, the supplemental feeding of pollen sub makes the difference
between taking 6-framers to almonds vs. 12 framers.

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

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