Data underlying the publication: Herbivore prevalence poorly predicts yield in diverse cropping systems

This data belongs to the paper published in Journal of Applied Ecology, with the title: Herbivore prevalence poorly predicts yield in diverse cropping systems. See the published paper and the readme files for information on methods, techniques and other relevant information.<br>Abstract:1. Industrialized agriculture needs sustainable alternatives to pesticides to avoid negative impacts on the environment and human health. Crop diversification is known to decrease pest pressure in agricultural crops. Up till now, effects of insect herbivores on crop yield are often assumed equal among cropping systems.2. We sampled the insect community and yield of cabbages in five distinct cropping systems characterized by increasing crop diversity. Using structural equation modelling, we assessed how herbivorous insects influence cabbage yield through direct consumptive effects and indirect effects via changes in the insect community.3. The most diverse cropping system synergistically increased cabbage yield and herbivorous insect abundance and richness, whereas the other cropping systems did not differ consistently among each other.4. Cropping systems alter the effect that herbivores have on cabbage crop yield, where more herbivores do not necessarily lead to reduced yields. Specific insects had cropping system specific effects on yield, which reflects differences in the potential for distinct cropping systems to contribute to biological control of distinct herbivorous insects.5. In one of the cropping systems with cultivar mixtures we observed negative impacts of herbivores on cabbage yield. This may result from a companioning cultivar drawing natural enemies away from the main cultivar, which would result in reduced biological control of herbivores on the main cultivar.6. <em>Synthesis and applications. </em> Our study shows that the design and characteristics of cropping systems should be considered when assessing insect herbivory effects on crop yield. As herbivorous insects have a smaller impact on yield in diverse cropping systems, crop diversification may synergize biodiversity conservation and food production.

本数据集隶属于发表于《应用生态学杂志》（Journal of Applied Ecology）的论文，论文标题为《植食者发生水平难以预测多样化种植系统的作物产量》。相关方法、技术及其他细节信息，请参阅已发表的论文与说明文件。
摘要：
1. 工业化农业亟需可持续的农药替代方案，以规避对环境与人类健康造成的负面影响。已知作物多样化可降低农田作物的虫害压力。截至目前，学界通常假定不同种植系统中昆虫植食者对作物产量的影响并无差异。
2. 我们在5个以作物多样性递增为特征的不同种植系统中，取样调查了白菜的昆虫群落与产量。通过结构方程模型（structural equation modelling），我们评估了植食性昆虫如何通过直接取食效应，以及经由昆虫群落结构变化产生的间接效应，对白菜产量产生影响。
3. 多样性最高的种植系统可协同提升白菜产量以及植食性昆虫的丰度与物种丰富度，而其余种植系统之间的表现未呈现一致差异。
4. 种植系统会改变植食者对白菜产量的影响效应：植食者数量更多未必会导致产量降低。特定昆虫类群对产量的影响具有种植系统特异性，这反映出不同种植系统在防控特定植食性昆虫的生物防治潜力上存在差异。
5. 在其中一个采用品种混播的种植系统中，我们观测到植食者对白菜产量产生了负面影响。这可能源于伴生品种将天敌从主栽品种上吸引走，从而削弱了主栽品种上植食者的生物防治效果。
6. **综合与应用（Synthesis and applications）**：本研究表明，在评估昆虫植食对作物产量的影响时，应考虑种植系统的设计与特征。由于在多样化种植系统中，植食性昆虫对产量的影响更小，作物多样化或可协同实现生物多样性保护与粮食生产的双重目标。