Data from: Landscape-level crop diversity benefits biological pest control

1.Landscape-level crop diversification is a promising tool for ecological intensification, whereby biodiversity and ecosystem services are enhanced, and pesticide applications reduced. Yet evidence for the effects of crop diversity at multiple scales and in different landscape contexts is lacking. Here, we investigate the potential benefits and context-dependencies of multiscale crop diversity on natural enemies and overall biological control in winter wheat. Simultaneously, we examine the mediating effects of bird predation on aphid regulation in this system. 2.Eighteen conventional winter wheat fields were selected along two independent gradients of crop diversity and seminatural habitat cover (SNH). We assessed biological control using a natural enemy exclusion experiment (‘Open Treatment’, ‘Bird Exclosure’, ‘Full Exclosure’). Biological control, predator and parasitoid densities within cages were analysed as functions of landscape (crop diversity x SNH), bird predation (yes/no) and temporal change (three surveys) on six spatial scales (100-3000 m). 3.Crop diversity rather than SNH enhanced aphid regulation in our study system. Biological control in fields with high landscape-level crop diversity was 8 to 33% higher than in low diversity landscapes, with main effects observed on scales <500 m. 4.Predator and parasitoid densities increased with crop diversity on small (100–250m) and large (2000-3000 m) spatial scales, respectively. Nevertheless, our findings suggest that natural enemies other than birds, parasitoids and aerial arthropods facilitated biological control. 5.Synthesis and applications. Our study shows that landscape-level crop diversification can improve biological control in agroecosystems. Therefore, increased crop diversity could lower dependence on insecticides while enhancing yield stability through ecological intensification of farming. We also highlight the need to assess biological control rather than natural enemy abundances to avoid bias due to sampling artefacts or species interactions. Lastly, simple measures of crop diversity (e.g. ‘effective number of crop types’) help in science communication and the development of farm management guidelines.1. 景观尺度作物多样化是生态集约化（ecological intensification）的有效手段，可提升生物多样性与生态系统服务，并减少农药施用。然而当前仍缺乏多尺度、不同景观背景下作物多样性效应的相关研究证据。本研究针对冬小麦系统，探究多尺度作物多样性对天敌及整体生物防治的潜在效益与背景依赖性；同时解析鸟类捕食在该系统中对蚜虫调控的中介效应。 2. 本研究沿作物多样性与半自然生境覆盖度（Seminatural Habitat Cover, SNH）两条独立梯度，选取了18块常规冬小麦田。通过天敌排除试验（设置"开放处理""鸟类排除处理""完全排除处理"三组）评估生物防治效果；以6个空间尺度（100~3000m）为基础，将笼内生物防治效果、捕食者与寄生蜂密度作为景观因子（作物多样性×SNH）、鸟类捕食作用（存在/缺失）及时间动态（3次调查）的函数进行分析。 3. 在本研究系统中，提升蚜虫调控效果的关键是作物多样性而非半自然生境覆盖度。景观尺度作物多样性较高的田块，其生物防治效果较低多样性景观田块提升8%~33%，且该主效应主要在<500m的空间尺度上显现。 4. 捕食者与寄生蜂密度分别在小尺度（100~250m）与大尺度（2000~3000m）上随作物多样性提升而增加。此外，本研究结果显示，除鸟类、寄生蜂与空中节肢动物（aerial arthropods）外的其他天敌类群，同样对生物防治起到了促进作用。 5. 结论与应用 本研究表明，景观尺度作物多样化可提升农业生态系统（agroecosystems）中的生物防治效果。因此，通过提升作物多样性，可降低农业生产对杀虫剂的依赖，并通过生态集约化实现产量稳定性提升。同时，本研究强调，应通过评估生物防治效果而非天敌种群丰度来开展研究，以避免采样伪迹或物种互作带来的偏差。最后，采用作物多样性的简易量化指标（如"作物类型有效数量"），有助于科学传播与农田管理指南的制定。