ABSTRACT
The urban footprint is expanding globally, which poses a biodiversity threat as the typical ‘cocktail’ of urban stressors—such as habitat fragmentation, urban heat, and various types of pollution—creates eco-evolutionary novel ‘urban’ conditions that homogenise insect assemblages via filtering of species with exaptations to these stressors. In turn, this homogenisation results in ecosystem-wide impacts of reduced ecosystem functioning and ecosystem services. Urbanisation constitutes not only an ecological challenge but also entails strong selection pressures to which some species are able to adapt, leading to functional differences among urban and rural populations. However, insect-poor cities can be transformed into insect-friendly cities via two complementary approaches: (i) increased and more diversified provision of habitat resources, via changes in urban design and management of urban green infrastructure; and (ii) reduced impact of urban stressors, for instance via urban policies to reduce impervious surface, soil compaction, chemical contamination, air pollution, urban heat, and light pollution. As different insects respond to urbanisation at different spatial scales, such mitigation measures need implementing across spatial scales to generate the most effective outcome across insect taxa. Also, a multi-scale approach leads to increased functional connectivity among habitat resources. The resulting higher abundance and diversity of insect assemblages in both terrestrial and aquatic urban habitats will improve the biological functioning of urban ecosystems across cities, thus providing more ecosystem services to human urban dwellers. This will also lead to positive impacts on human well-being. Cities and urban planners now face the urgent task to better integrate and harmonise insect biodiversity and urban development into urban design and management, so that resilient insect communities support robust ecosystem functions and services in the Anthropocene’s urban habitats.
