Pollen metabarcoding of old and recent Bombus specimens reveals different foraging characteristics

This study demonstrates how pollen metabarcoding can infer historic and recent interactions between plants and bumblebees. We sampled bumblebees from the same locations from historical collections and in the field (1968/69 and 2019) and barcoded the pollen attached to their bodies using the ITS1, ITS2 and trnL-P6 loop plant barcode markers. Our results show different trends in foraging habits between the two points in time, mostly determined by fewer Fabaceae interactions in 2019. Technically, we demonstrated the usefulness of the ITS1 marker and the utility of the trnL-P6 loop with degraded DNA. The successful application of scalable molecular methods to historic pollen samples shows the usefulness of museum collections.