Global environmental changes threaten biodiversity and the interactions between species, and food-web
approaches are being used increasingly to measure their community-wide impacts. Here we review how
parasitoid–host food webs affect biological control, and how their structure responds to environmental
change. We find that land-use intensification tends to produce webs with low complexity and uneven
interaction strengths. Dispersal, spatial arrangement of habitats, the species pool and community differences
across habitats have all been found to determine how webs respond to landscape structure, though
clear effects of landscape complexity on web structure remain elusive. The invasibility of web structures
and response of food webs to invasion have been the subject of theoretical and empirical work respectively,
and nutrient enrichment has been widely studied in the food-web literature, potentially driving
dynamic instability and altering biomass ratios of different trophic levels.