Molecular Epidemiology and Temporal Dynamics of Nosema apis and Nosema ceranae in Honey Bees (Apis mellifera) from West Kazakhstan

HistoryNosemosis is a widespread microsporidian infection affecting honeybees.It significantly affects the health, productivity, and survival of the colony.This study aimed to investigate the molecular epidemiology and temporal dynamics of Nosema apis and Nosema ceranae in Apis mellifera colonies.The study was conducted in the West Kazakhstan Region over a period of five years (2021)(2022)(2023)(2024)(2025).A total of 720 colony-level samples were collected from 169 apiaries across different climatic zones.Initial screening was performed using light microscopy.On the other hand, species identification and confirmation were conducted using multiplex PCR.The results revealed a substantial increase in the prevalence of nosemosis over time.The infection rates rose sharply after 2022.Molecular analysis revealed a clear shift in the pathogen's composition.N. ceranae progressively replaced N. apis as the dominant species.Mixed infections were detected at low but increasing frequencies.Multiplex PCR showed higher sensitivity than microscopy, particularly for detection of low-intensity and subclinical infections.Statistical analysis identified apiary density as a significant risk factor associated with higher infection rates and an increased likelihood of N. ceranae dominance.Phylogenetic analysis based on 16S rRNA gene fragments indicated that regional N. ceranae isolates form a distinct evolutionary cluster.These results suggested possible local adaptation to arid continental conditions.Overall, findings highlight a transformation in the epidemiological profile of nosemosis in the region.This study emphasizes the importance of integrating molecular diagnostics into routine surveillance and provides valuable insights for developing targeted disease management strategies to support sustainable beekeeping.