Anthropogenic influences on resources and consumers affect food web regulation, with impacts on trophic structure and ecosystem processes. Identifying how these impacts unfold is challenging because alterations to one or both resources and consumers can transform community structure with similar outcomes especially to intermediate consumers. To date, empirical testing has been limited by the difficulty in separating the direct effects of perturbation on trophic dynamics versus those unfolding indirectly via altered feeding pathways, and disentangling the impacts of co-varying stressors that characterize human-altered systems. We examine these issues with a 25ha grassland meta-community experiment, testing how resource inputs, stand perturbation, and spatial factors affect three trophic levels of insect food webs. Using path-model comparisons, we find significant simplification of food web regulation on herbivores, shifting from mixed predator-resource regulatory model in unaltered mainland areas to strictly resource-based regulation with landscape fragmentation. Most changes were attributed to plant community homogenization caused by landscape fragmentation and the deterministic influence of eutrophication reducing among-patches beta-diversity. This lead to a simplified food web dominated by fewer, but more abundant herbivore populations. Our work implies that anthropogenic perturbation relating to resources and spatial isolation should transform the regulation of food web diversity, structure and function.