This report is just out on PLoS. It suggests that feral bees are not different from managed bees
Thompson CE, Biesmeijer JC, Allnutt TR, Pietravalle S, Budge GE (2014) Parasite Pressures on Feral Honey Bees (Apis mellifera sp.). PLoS ONE 9(8):Nosemosis C is an emerging disease in Europe caused
by N. ceranae, yet is found to be well established in feral
colonies. This result could suggest a degree of parasite perturbation
between feral and managed populations.
We can conclude that the sampled feral population contained
many of the parasites commonly found in managed populations.
Therefore, our study provides no evidence that feral-nests reduce
parasite load compared to managed nests.
Crucially, the levels of DWV were far higher
in feral colonies compared to managed colonies, which could
reflect the absence of Varroa control in feral colonies.
Interestingly managed colonies not treated for Varroa contained
similar virus levels to feral colonies. DWV is the most
prevalent known virus in managed honey bee colonies in Europe
and an increasing proportion of viruliferous Varroa mites has been
linked to reduced colony survival. Colonies with high levels of
DWV show evidence of a scattered brood nest, crippled bees, loss
of coordinated social behaviour such as hygienic behaviour, queen
attendance and a rapid decline in the colony’s bee population