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...1. 农业景观以随空间与时间动态变化的作物镶嵌景观为核心特征。过往研究多已证实半自然生境可助力害虫生物防治，但农田景观异质性提升所带来的效应却长期被忽视。本研究旨在探究作物镶嵌景观的组成与结构，以及因作物轮作导致的该景观的年际变化，如何对麦蚜（cereal aphids）、其天敌及生物防治效果产生影响。2. 本研究于两年内，在51块冬小麦田中针对麦蚜、天敌种群数量以及蚜虫寄生率开展调查。研究人员在距田缘（field borders）0、10、30米的三个距离梯度上监测节肢动物（arthropods）群落。所选田块均嵌入直径1千米的景观单元内，这些景观单元沿三个正交梯度选取：作物组成异质性（作物多样性）、结构异质性（田缘与草本田界长度），以及蚜虫寄主生境（谷类作物、玉米与牧草……）覆盖度的年际变化。