The feral lines discovered by Delaney, Szalanski, and others show that
when given that opportunity the bee is able to adapt and overcome novel
threats such as varroa.

This is only partially true. In their paper, Delaney, Seeley et al suggest several reasons why feral bees may be surviving. 

> Colonies living in the wild are dispersed over the landscape, whereas colonies managed by beekeepers are crowded in apiaries. When colonies are widely separated, their parasites and pathogens are probably transmitted mostly vertically (from parent colony to offspring colony) through swarming, but when living side by side in apiaries, their disease agents are easily transmitted horizontally (between unrelated colonies) through drifting and robbing behaviors.

> What apicultural practices might be causing harm? We suggest that the following four are important: (1) giving colonies mite-control treatments, so there is little or no selection for mite-resistant bees; (2) crowding colonies together in apiaries, so that horizontal transmission of diseases is favored; (3) managing colonies to be unnaturally large, so that they have high honey production and low swarming rates; and (4) moving colonies from place to place, so that there is both strong gene flow that prevents natural selection from altering local allele frequencies in a closed population, and rapid spread of pathogens.

Given these four, they do not single out any one as the main factor. Any one of these alone could be the deciding factor, most probably (in my opinion) the wide dispersal. The colonies are found at a density of _one_ per square kilometer. Commercial beekeeping often reaches a density of 100 per km2.

Further, they point out that the bees are not from different stock than the usual honey bees found in beekeepers hives:

> Our autosomal analyses show genetic differences between the wild and managed colonies within the study area, but our mitotyping analysis suggests that the population of wild colonies contains little genetic material from A. m. mellifera (M haplotype) but much from A. m. ligustica and A. m. carnica (both C haplotype).

Seeley, T. D., Tarpy, D. R., Griffin, S. R., Carcione, A., & Delaney, D. A. A survivor population of wild colonies of European honeybees in the northeastern United States: investigating its genetic structure. 2015. Apidologie, 1-13.

             ***********************************************
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