Survival mechanisms of preselected breeder honeybee (Apis mellifera) colonies under Varroa-infestation: Selective breeding of natural selection.

Including other stressors, global losses of honeybee colonies are attributed to Varroa destructor. Among control measures, breeding resistant bee strains are promising and eco-friendly, though the mechanisms involved are complex. This study evaluated mite fall, mite population, colony development (brood and adult population), and viral infestations across three groups: Group A (hygienic, low grooming), Group B (non-hygienic, high grooming), and Group C (Intermediate traits) from June to October 2024. Groups B and C had lower colony mortality than Group A. Although the average number of fallen mites and overall mite population were not significantly different among the groups, the number was higher in groups A and C. Daily mite fall showed no significant correlation with adult bee populations. However, significantly weak negative correlations were observed between the brood population and daily mite fall. Deformed wing virus, Acute bee paralysis virus, Isreali acute paralysis virus, and Chronic bee paralysis virus were detected. Deformed wing virus, acute bee paralysis virus, and Isreali acute paralysis virus showed high levels of expression. This study highlights that non-hygienic bees with high grooming activity can perform better against V. destructor. Further research should evaluate the level of resistance in hygienic bees with short postcapping brood duration, grooming bees with short postcapping brood duration, and Varroa sensitive hygiene bees with short postcapping brood duration.