Data from: Metabarcoding of trap nests reveals differential impact of urbanization on cavity-nesting bee and wasp communities

Urbanization is affecting arthropod communities worldwide, for example by
changing the availability of food resources. However, the strength and
direction of a community’s response are species-specific and depend on the
species’ trophic level. Here, we investigated interacting species at
different trophic levels in nests of cavity-nesting bees and wasps along
two urbanization gradients in four German cities using trap nests. We
analyzed bee and wasp diversity and their trophic interaction partners by
metabarcoding the DNA of bee pollen and preyed arthropods found in wasp
nests. We found that the pollen richness increased with increasing
distance from city centers and at sites characterized by a high percentage
of impervious and developed surfaces, while the richness of pollinators
was unaffected by urbanization. In contrast, species richness of wasps,
but not their arthropod prey, was highest at sites with low levels of
urbanization. However, the community structure of wasp prey changed with
urbanization at both local and regional scales. Throughout the study area,
the community of wasps consisted of specialists, while bee species were
generalists. Our results suggest that Hymenoptera and their food resources
are negatively affected by increasing urbanization. However, to understand
the distribution patterns of both, wasps and bees in urban settings other
factors besides food availability should be considered.