Temporal variations in the species compositions of pollinator assemblages in grassland environments under strong urban influences

Abstract

Temporal studies of insect assemblages provide valuable insights into the mechanisms through which communities differ across observation periods, especially in dynamic urban environments where certain insects find refuge. The aim of this study was to describe the temporal variations in pollinator assemblages in an urban context. We studied two insect taxa (i.e., day-active butterflies and flower-visiting beetles) across three periods in Pardubice, Czech Republic. Butterfly assemblages shifted toward species poor communities with relatively high numbers of generalists, whereas beetle assemblages appeared to be increasingly stable and, in some cases, showed persisting or appearing specialists. Our results suggest that urban environments can support different insect groups, albeit unequally. These findings highlight the need to consider urban habitats as potentially valuable for insect conservation while recognizing the increasing influences of built-up areas and the limitations of short-term temporal datasets. Implications for insect conservation Effective urban pollinator conservation requires taxon-specific management, specifically transitioning to mosaic mowing regimes to protect declining butterfly specialists and actively retaining dead wood in parks to support resilient saproxylic beetles. Furthermore, protecting existing urban green spaces from further densification is crucial for maintaining these habitats and overall local biodiversity.