PLB started an August 2011 thread (linked to this message) reporting research by Dr. Heather Mattila  and Gard Otis on accelerating the timing of the transition to winter bees by forcing a pollen dearth,  and alternatively delaying it through offering pollen substitute.   

The paper surprises me, due to the nearly universal efforts to supply California bee with autumn pollen sub.  This, of course, is due in no small part to the climate, and the need for Almond frame count.

Accounts of a talk Heather Mattila gave in Alberta were reported in the thread, and she reported on the need for drought year suplementation to the natural Goldenrod pollen that formed the autumn pollen source for her study hives.

I am curious whether in the years since this paper was written if further studies and research has been done on the utility of providing autumn sub,  or whether a restricted suplementation calendar (such as recommended by Mattila in her talk -- to restrict supplementation to the natural pollen period) has been trialed in California (or other warm winter bee regions).

For many years, I only began pollen sub following the bloom of the Blue Gum Euc and Arroyo Willow (January), but this was a consequence of Argentine ant invasion and robbing earlier in the winter.  Recently, I have been putting sub on in early September, to "goose" the fall hives,  but the Mattila research calls that into question.

The two most relevant papers to this question I find are:
http://onlinelibrary.wiley.com/doi/10.1111/j.1365-2311.2007.00904.x/abstract
MATTILA, H. R. and OTIS, G. W. (2007), Dwindling pollen resources trigger the transition to broodless populations of long-lived honeybees each autumn. Ecological Entomology, 32: 496–505. doi:10.1111/j.1365-2311.2007.00904.x

and 

Manipulating pollen supply in honey bee colonies during the fall does not affect the performance of winter bees
    Heather R. Mattila (a1) and Gard W. Otis (a1)
        https://doi.org/10.4039/n06-032

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