Tage der Biodiversität 2027

Plant diversity and species composition in grasslands significantly influences wild bee diversity. However, traditional botanical records often lack detailed historical data on plant abundances, limiting our ability to reconstruct long-term changes in floral resources. DNA metabarcoding provides a powerful method for comparing the foraging plants of wild bees across time.

One of the most significant collections of Central European bees from the mid-20th century is the Bruno Pittioni Collection, preserved at NHM London. The locality of Stammersdorf, a former village belonging to Vienna today, was selected as a study site due to the high number of specimens from this locality in Pittioni’s collection. Recent samples were collected for comparison. Pollen was removed from the scopae of the bees, and the plant DNA was amplified using rbcL and ITS2 markers using DNA metabarcoding.

Preliminary results showed successful DNA extraction from all recent samples, while only approximately 40% of the historical samples yielded retrievable DNA. In total, pollen data were successfully obtained from 48 historical bees and 82 recent bees. They represented 124 plant taxa overall, with 66 plant taxa detected in historical samples and 97 in recent ones. Species accumulation curves indicate that sampling saturation was not reached, particularly for the historical dataset. Extrapolation suggests a slightly higher plant diversity in recent samples after accounting for the unequal sample size, and a significantly differing community composition between historical and recent periods. Historical samples contained a higher proportion of anemophilous and woody-plant pollen than recent samples, suggesting a constrained floral resource availability in the 1940s.

This study highlights the potential of museum collections as valuable archives for reconstructing historical plant–pollinator interactions and improving our understanding of long-term changes in wild bee ecology and land-use.