Positive Edge Effects of Natural Habitats Produce Matching Response in Beetle Population and Plant Morphometry in Amaranth Crop

Components of a surrounding agricultural matrix can be important to the ecology of agroecosystems because they modulate biodiversity, abundance of pests (i.e., arthropods or weeds), and their natural enemies. Based on the assumption that organisms respond to edges, we assessed whether animals (beetles) and crop plants showed similar patterns across a gradient of perturbation and ecotones and natural habitats. Across the perturbation gradient, we analyzed (1) crop plant morphometry and (2) the structure of beetle populations in the perturbed area and natural habitats. Results showed that beetles (a bioindicator group) and A. hypochondriacus crop plants (perturbed area) responded similar to an ecotone, i.e., we found positive edge effects, but beetle richness negatively followed the gradient of perturbation affecting beetle nestedness and turnover. At the point nearest the ecotone, crop plants grew larger (e.g., panicle and plant height had the largest effects), which was consistent in time. Results supported the resource competition framework and resource distribution model in agroecosystems.