Quoted material:

We report a managed A. mellifera population in Norway, that has been naturally surviving consistent V. destructor infestations for >17 years.

Experiments were conducted in the Østlandet region, Norway, during local late summer
and early fall 2015. Surviving colonies were of a mixed origin (Buckfast) that had been kept
without any V. destructor treatments for 19 years prior to the study. After the last treatment
against V. destructor in 1997, mite levels seemed to increase and substantial losses of
colonies occurred. However, surviving and healthy colonies were split and used to replace
lost ones. Over the last 10 years, colony losses have been lower than the national average of
about 10%.

Our data support the view that reduced V. destructor reproductive success is a prime
requisite for natural survival of infested A. mellifera colonies. Indeed, both mite
reproductive success and mite population levels were significantly lower in surviving
Norwegian colonies compared to local susceptible controls. The proportions of damaged
mites as a proxy for the efficacy of grooming behavior and brood removal (VSH) by
adult workers were not significantly different between surviving and susceptible colonies,
indicating that these two mechanisms are unlikely to explain the natural survival of these
mite-infested Norwegian honey bee.

Oddie, M. A., Dahle, B., & Neumann, P. (2017). Norwegian honey bees surviving Varroa destructor miteinfestations by means of natural selection (No. e2976v1). PeerJ Preprints.

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