> We have read for decades that annual requeening can help prevent "queen failure." This appears to not be the case...

I have been saying this for years in this forum, the response has been catcalls.  But many (purchased) queens do not remain productive for even a year since the 2008-2010 timeframe.

We "large-city urban beekeepers" notice this, because our colonies do not supersede.  (To explain, successful queen matings have yet to be verified in Manhattan, despite the 900+ acres of Central Park, or in Brooklyn, despite the 520 acres of Prospect Park.  One has to go north to Bronxville/Yonkers or east to Kew Gardens to see queens mate.  Optimistic early reports of an unmarked, and therefore clearly new queen are consistently premature - no such queen has proven to be more than a flash in the pan.) 

Dave Tarpy (NC State) has been looking at this intensively for more than a decade, and has a very long list of well-designed experiments, each which proved that the "queen problems" were NOT due to this or that or the other.  The list of possible causes ruled ou20t is very long, and the sample sizes are much larger than in the Pettis/Spivac/Browning paper cited.

The paper cited draws the unsurprising conclusion that (a) nutrition [metric: pollen collected] (b) brood rearing [metric: sealed brood] and (c) varroa [metric: Varroa levels] are key factors.

This paper is a classic example of the LPU, (the "Least Publishable Unit") resulting from a study that was not focused enough to say something definitive that was not already common knowledge.

Read Tarpy's stuff - he's got more data, and more focused data.  But we still don't know why.

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