Landscape-scale interactions of spatial and temporal cropland heterogeneity drive biological control of cereal aphids

1. Agricultural landscapes are characterised by dynamic crop mosaics changing in composition and configuration over space and time. While semi-natural habitat has been often shown to contribute to pest biological control, the effects of increasing landscape heterogeneity with cropland has been disregarded. Here, we examine how cereal aphids, their enemies and biological control are affected by the composition and configuration of the crop mosaic and its inter-annual change due to crop rotation. 2. We studied the abundance of cereal aphids, natural enemies and aphid parasitism over two years on 51 winter wheat fields. Arthropods were monitored at three distances (0, 10, 30m) from field borders. Fields were embedded in landscapes of 1-km diameter selected along orthogonal gradients of compositional crop heterogeneity (crop diversity), configurational heterogeneity (field border and grassy field boundary length) and inter-annual change in cover of aphid host habitats (cereal, maize and gra...