Genomic Signatures of Selection and Adaptive Genetic Determinants of Varroa Resistance in Apis Mellifera Intermissa

Apis mellifera intermissa, the North African honey bee subspecies, exhibits remarkable adaptation to diverse climatic conditions and natural resilience against pathogens, including the ectoparasitic mite Varroa destructor. This review summarizes current knowledge on the molecular, genomic, proteomic, and behavioral traits that underlie its resistance to environmental stressors and varroosis. The subspecies demonstrates high genetic diversity and heterozygosity, active immune pathways, antimicrobial peptide production, and stress-response proteins that collectively support colony health. Behavioral mechanisms, particularly hygienic and grooming behaviors, reduce mite loads and limit pathogen transmission, while ecological and colony-level factors further modulate resistance traits. Integrating molecular, behavioral, and ecological evidence highlights the multilevel nature of Varroa resistance and identifies candidate genes and pathways associated with hygienic behavior and immunity. Morphometric studies suggest physiological resilience in colonies with strong defense traits, emphasizing the potential for targeted breeding programs. This comprehensive review underscores the importance of Apis mellifera intermissa as a model for sustainable apiculture in North Africa and provides insights for enhancing colony resilience and productivity. Future research should focus on genomic and epigenetic mechanisms, microbiome interactions, and the influence of environmental factors on resistance traits to support the development of Varroa-tolerant populations.