Microplastics (MPs), pervasive pollutants found in various environmental matrices, pose growing ecological and health concerns. Honeybees (Apis mellifera carnica), owing to their broad foraging behavior and environmental sensitivity, have been proposed as potential bioindicators for environmental pollution, including microplastics. This study investigates whether honeybees can act as proactive samplers of MPs in urban environments. Over a one-year period, 1215 honeybee specimens were systematically collected from nine distinct urban locations in Croatia, with standardized protocols ensuring consistency in hive sampling, processing, and analysis. The collected bees underwent a multi-step laboratory protocol involving physical separation, chemical digestion, and stereomicroscopic examination for the presence of MPs, categorized by size, shape, and color. Despite the comprehensive and rigorous sampling and analytical procedures, no microplastic particles were detected on or within the bee specimens. The absence of MPs may reflect the relatively low environmental contamination at the selected sampling sites, which were intentionally chosen to avoid heavy industrial or traffic-related sources. Additionally, reduced human activity during the COVID-19 pandemic may have further contributed to lower microplastic presence. These findings emphasize the need for broader and more diverse sampling efforts across different environmental contexts and beekeeping practices to validate the initial results. Future studies involving private apiaries and expanded geographical coverage could offer deeper insights into the feasibility of using honeybees as sentinel organisms for microplastic monitoring.

Acknowledgement: This work was carried out within the project "Food Safety and Quality Center" (KK.01.1.1.02.0004). The project is co-financed by the European Union throughthe European Regional Development Fund.