Varroa destructor poses a major global threat to Apis mellifera by feeding on host tissues, weakening colonies, and vectoring viruses. Sustainable management relies on breeding Varroaresistant bees to reduce dependence on chemical controls. Honey bee behaviors such as grooming, hygienic behavior, and uncapping-recapping are known to contribute to the bees' ability to detect and remove mites. Additionally, Varroa Sensitive Hygiene (VSH) and traits associated with suppressed mite reproduction (SMR) are important in limiting the mites' reproductive success within brood cells. This work synthesizes genetic and mechanistic factors underlying Varroa resistance, with emphasis on behavioral traits and candidate genes, and integrates ecdysone biology as a key driver of mite reproduction. We conducted a literature synthesis of genomic studies (GWAS, SNP mapping, QTL) in Varroa-tolerant honey bee populations and reviewed behavioral genetics linked to grooming, hygienic behaviors (VSH, SMR), which were phenotyped and documented in the UOK research apiary. We also integrated knowledge on ecdysone biology, noting that host-derived ecdysone drives Varroa reproduction while the mite itself cannot synthesize this hormone, and identified candidate genes in ecdysone synthesis and signaling (e.g., Mblk-1, Cyp18a11, Phantom). Across resistant populations, there is a consistent pattern of reduced Varroa reproduction, with associated loci on chromosome 15 and grooming-related regions on chromosome 5. Candidate genes reveal mechanistic links between hormonal signaling and behavior in shaping resistance. A gene-to-phenotype framework emerges, wherein host genes and pathways influence mite fecundity and defensive behaviors, providing a coherent basis for marker-assisted and genomic selection in breeding programs. The findings have clear implications for breeding practicability. Marker-assisted and genomic selection can be used to enhance Varroa resistance by targeting both behavioral traits and hormonal pathways. This approach supports the rapid development of resistant commercial lines, while acknowledging the need for cross-environment validation and monitoring for potential trade-offs with productivity or genetic diversity. Conclusion: Advancements in highdensity genomic markers, including SNP panels and whole-genome sequencing, enable precise Genomic Selection (GS) for Varroa resistance. By linking thousands of SNPs to resistance phenotypes, breeding values can be predicted with greater accuracy, accelerating gains in commercial bee populations. The integrated genomic–phenotypic pipeline supports commercial deployment of Varroa-resistant lines with lower mite loads, reduced chemical use, and sustained productivity, promoting safer honey product and environmentally friendly apiculture.
