>  Any results are suspect if you start with a mixed bag of healthy to Varroa and nosema infested bees. That is the most important variable to control. It is obvious it was not."

With bees all over the place this could not be controlled. But it should have acknowledged as a primary factor. Like this study:

The present studies are the second part of the research project dedicated to finding the causes for increased winter mortality of honey bee colonies. The aim of this task was to investigate incidents of overwintered colonies’ death with regard to the potential interrelation to the exposure to pesticides. The samples of winter stores of bee bread and sugar food (honey or syrup processed by bees), beeswax and bees collected from apiaries with low and high rates of winter colony mortality were searched for acaricides used to control V. destructor and plant protection pesticides.

The level of pesticide contamination (frequency, concentration, toxicity) of hive products and bees originating from apiaries with both a high and low winter colony survival rates, was similar, which created a similar extent of risk. Although the multiple varroacides and pesticides were present in the hive environment we did not find unequivocal links between their residues and high winter colony mortality.

Exposure to pesticide residues in apiaries with high and low rates of winter colony mortality ... leading to the conclusion that in the surveyed apiaries contamination of the hive environment with pesticides was not the main reason for the decline of colonies during the winter. While, in apiaries with high colony losses the assessment of the epizootic state of these colonies showed significantly higher V. destructor infestation, the prevalence of deformed wing virus and acute bee paralysis virus.

Finally, the present results confirm the previously proven thesis that in most national apiaries the mentioned above pathogens are a primary and direct cause of the increased winter mortality in honey bee colonies, but this does not mean that chronic exposure to pesticide does not have a side effect on bees.

Pohorecka, Krystyna, et al. "The Exposure of Honey Bees to Pesticide Residues in the Hive Environment with Regard to Winter Colony Losses." Journal of Apicultural Science 61.1 (2017): 105-125.

             ***********************************************
The BEE-L mailing list is powered by L-Soft's renowned
LISTSERV(R) list management software.  For more information, go to:
http://www.lsoft.com/LISTSERV-powered.html