I had posted a question earlier regarding the U of  Guelph research on protein restriction and "winter bees".   I wanted to know how this research should inform management of sub feeding to temperate California bees.

Recently,  I caught up with Dr. Gordon Wardell,  and had a long conversation with him on this subject.     He presented an alternate theory, one that seems to fit the observations I see.

Dr. Wardell felt the demography of the hive drove "winter" vs. "summer" bee development,  specifically the ratio of larvae to nurse age adults.    

In a peak expanding summer colony,  there is one nurse bee to many, many hungry larvae,  and the consumption of royal jelly is maxed out to the ability of nurse bees to feed the larvae.  In an autumn colony,  where the brood nest is contracting,  the nurse bee population is larger in numbers than the remaining larvae (as each generation is smaller than the previous).

That demographic shift creates nurse bees with surplus nutrition,  and the extra protein is stored as fat bodies.    The fat bodies "dilute" the effect of juvenile hormone releases -- and this slows the caste transition from house bees.   It is only at spring brood up does the consumption of protein "release" the house bees to make the forager transition.

In this sequence (vitellogenin is sequestered rather than royal jelly produced > reduced effect of hormone),  the experimental manipulations of protein are the effect rather than the cause.   A deliberately "starved for protein" hive collapse egg laying/larvae production (to the extent of the well-observed parasitism by workers on larvae)  and the reduction in brood relative to the nurse bee caste unbalances the demography and changes the response to Juvenile Hormone.    

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