Detection patterns of honey bee diseases in clinically healthy colonies under long-term surveillance

Honey bee (Apis mellifera L.) health is increasingly threatened by pathogens, yet little is known about their circulation in clinically healthy, closely monitored colonies. We screened 820 adult bees from 22 colonies in Northern Greece using PCR-based assays for major viral, bacterial, and parasitic agents. Acute Bee Paralysis Virus (ABPV) and Black Queen Cell Virus (BQCV) were universally detected, while Varroa Destructor Virus 1 (VDV1/DWV-B) (18.2%) and Vairimorpha ceranae (4.5%) appeared sporadically. All other pathogens tested were absent. These results support a classification of baseline, risk, and exclusion markers, offering a diagnostic reference that strengthens risk-based surveillance and sustainable apiculture.