In a follow-up paper, Genersch et a

In a follow-up paper, Genersch et al. (2010) provided a more detailed assessment of the German Bee Monitoring Project. All data were statistically analysed in respect to the overwintering mortality of the colonies. It was demonstrated for several factors that they are signifificantly related to the observed winter losses of the monitored honey bee colonies as previously described, i.e. high Varroa infestation level and virus infection (specififically deformed wing virus (DWV) and acute bee paralysis virus (ABPV)) in autumn. A clear signifificant effect was shown for the age of the queen: colonies that survived the winter had on average signifificantly younger queens compared to the colonies that collapsed during winter. A clear effect on overwintering success was also found for colony strength (number of bees) in October. There was no signifificant difference in overwintering success between apiaries with no pesticide residues in the bee bread and those with higher amounts of residues. In addition, there was no signifificant correlation between winter losses and the amount of oilseed rape pollen in the honey harvested in summer (in Germany, oilseed rapeseed was almost 100 % treated with neonicotinoid insecticides during the monitoring period). Some residues were identifified in bee bread although mainly substances which are considered non-toxic for bees and the observed amounts of the residues were quite low i.e., three orders of magnitude lower than the respective LD50 values. Accordingly, no relation between chemical residues in pollen and colony development or winter losses could be demonstrated even though particular emphasis was put on this aspect.