Genetic diversity assessment of Italian honey bee populations for conservation of Apis mellifera ligustica biodiversity

The European honey bee (Apis mellifera) is a key pollinator of significant ecological and economic importance. However, its genetic biodiversity is increasingly threatened by human practices such as queen trade and migratory beekeeping, which facilitate introgression with non-native subspecies. In this study, we investigated the genetic composition of three A. m. ligustica queens from apiaries located in the Conero Park (Marche region, Italy) by performing whole-genome sequencing (WGS) of their drones. For comparison, additional genomes from A. m. ligustica, A. m. carnica, A. m. siciliana, A. m. mellifera, and Buckfast bees were included. Principal component and admixture analyses confirmed the assignment of the Conero queens to the ligustica lineage while revealing weak introgression signals in one apiary, primarily from carnica subspecies. The ongoing introgression suggests a limited introduction of alleles characteristic of other subspecies that are not adapted to the specific territory. Moreover, a set of private single-nucleotide polymorphisms (SNPs) specific to the ligustica genetic makeup was identified, representing valuable markers for monitoring and conservation. These findings emphasize the importance of conserving the local gene pool and implementing genetic monitoring strategies to safeguard the adaptive traits and resilience of Italian honey bee populations.