The number of wild bees and cavity‐nesting wasps is abundant in agricultural areas
and they contribute significantly to ecosystem services. Due to their specialization
in nesting sites and food sources, these groups are sensitive to habitat condition
changes and they are therefore important indicators for environmental impact assessments.
As semi‐natural habitats are steadily declining and often understudied, their significance
for research is increasingly recognized. During this research, the role of wild bee
species and cavity‐nesting Hymenopteran taxa as indicators was examined, along the
unique combination of high nature value and traditional land use habitats in Eastern
Europe, Transylvania. Transects and trap nests were used to test the diversity and
abundance of wild bees and cavity‐nesting Hymenopterans to identify possible differences
between highly protected and less protected areas. The differences in taxonomic groups
between the sites and the potential effects of landscape structure on wild bees and
cavity‐nesting Hymenopterans were also assessed. We detected a high diversity of wild
bee species and a significant species replacement from one study year to another.
Among the nest‐building Hymenopteran taxa, the majority of nests was built by Trypoxylon
sp. during both study years, with a stronger dominance in the second year. The different
taxonomic groups of wild bees and cavity‐nesting Hymenopterans showed differences
in their habitat affinities. The majority of the sampled bumblebee species as well
as Trypoxylon sp. had an affinity towards the study sites located within the highly
protected study area. Altogether, we found different habitat preferences for different
Hymenopteran groups (both wild bees and wasps) and conclude that these groups definitely
have the potential to serve as indicators for differences in the intensity of land
use.
