Data from: Local habitat, not landscape diversity, drives richness and reproduction of cavity-nesting bees and wasps in agricultural landscapes

Studying insect decline in human-dominated landscapes, especially in
intensively managed agricultural areas, requires understanding its
drivers. Studies of cavity-nesting bees and wasps with trap nests provide
information on the number of locally reproducing species and their
potential offspring, and how this relates to local resources and landscape
diversity. We investigated insect communities across all major habitat
types in agricultural landscapes using a grid-based design to evenly and
proportionally cover the major habitats of the landscape plots. The
landscape plots covered a gradient from complex landscapes with a variety
of habitats to simple landscapes dominated by arable land. At the local
scale, we found that bee species richness was highest in grasslands and
orchard meadows and lowest in forests, mirroring the pattern of local
floral resources. However, it was unaffected by local hedgerow cover. Wasp
species richness was highest in forests, followed by orchards, and lowest
in grasslands and arable land, and it also responded positively to
hedgerows. Bee brood cell abundance was highest in orchards and lowest in
forests, whereas wasp brood cell abundance showed the opposite pattern.
Neither group was affected by hedgerows. At the landscape scale, landscape
diversity neither affected species richness nor the number of brood cells
of bees and wasps. Our results highlight the importance of local habitat
diversity in agricultural landscapes for supporting diverse cavity-nesting
bee and wasp communities, as bees benefit from flower-rich grasslands and
orchards, while wasps rely on forest resources. To counteract insect
decline, conservation efforts should target both seminatural and
cultivated habitats.