Complex community and evolutionary responses to habitat fragmentation and habitat edges: what can we learn from insect science?

•Responses to habitat edges focus on bottom-up changes in resources, usually a bi-trophic view.•A species’ edge response affects the entire foodweb in ways that are currently not predictable.•Edge responses cascade up and down foodwebs and altered species interactions may affect evolutionary processes.

Habitat fragmentation is the primary factor leading to species extinction worldwide and understanding how species respond to habitat edges is critical for understanding the effects of fragmentation on insect diversity in both natural and managed landscapes. Most studies on insect responses to the habitat edge focus on bottom-up changes in resources. Only a few recent studies have examined multi-trophic responses to habitat edges; the results of these studies highlight the problem that we lack a conceptual framework to understand the complex results observed when a single species’ response to an edge ‘cascades’ throughout the food web in ways that are currently not predictable. Recent research from insect systems suggests that habitat edge responses cascade both up and down multi-trophic foodwebs and these altered species interactions may affect evolutionary processes. Future studies that investigate the effects of habitat edges on both ecological and evolutionary dynamics can help to fill these knowledge gaps and we suggest that insects, with short generation times, present an ideal opportunity to do so.