Metabarcoding of Pollen Carried by Syrphids Reveals Novel Plant–Pollinator Interactions in a Protected Natural Area and Agricultural Sites

In recent years, there has been growing concern over the global decline of pollinators, which poses a significant threat to biodi-versity, food security, and ecosystem health. While the role of bees has been widely studied, the contribution of other pollinatortaxa remains poorly understood. This preliminary study assessed plant-pollinator interactions through metabarcoding analysisof pollen collected from syrphids sampled in the Dolomiti Bellunesi National Park (Veneto, Italy) and in agricultural areas ofEmilia-Romagna (Italy), where flowering strips with specific seed mixtures were sown to enhance natural enemy and pollina-tor resources. Detailed protocols for specimen collection, DNA extraction, amplification, purification, and body surface pollenload evaluation were included in the paper. Pollen loads were evaluated on 200 specimens, while metabarcoding analyses wereconducted on 36 specimens. Metabarcoding revealed pollen from 18 plant families and 33 genera, with Asteraceae exhibitingthe highest number of plant genera visited. Syrphids were confirmed to contribute to the pollination of anemophilous plants,and several previously undocumented interactions were identified, including that between Microdon mutabilis/myrmicae andthe genus Orchis. Female syrphids carried significantly higher pollen loads than males, and pollen load was positively correlatedwith mean body size in females. These findings highlight the ecological importance of syrphids as pollinators and provide newinsights into plant-pollinator networks.