Biotic and abiotic factors at local to landscape scales influence insect pest and disease dynamics in agricultural systems. However, relative to studies focused on the importance of these drivers of crop plant damage in rural agricultural systems, few studies investigate plant damage from herbivore insects and plant diseases in urban agroecosystems, and consequently, most urban farmers lack knowledge on crop protection tactics. Here we use three common crop species within urban agroecosystems (community gardens) distributed across an urban landscape as a model system to ask how local, landscape, and microclimate factors relate to herbivore and disease plant damage. We hypothesized that plant damage would be lower in gardens with greater local vegetation complexity, landscape‐scale complexity, and less variable temperatures, but that the importance of factors is species‐ and damage‐specific. By measuring Brassica, cucurbit, and tomato insect pest and disease damage across the growing season, we confirmed that the importance of factors varies with crop species and by damage type. Both local complexity factors (e.g., number of trees and shrubs) and landscape complexity (percent natural cover in the landscape) relate to lower incidence of herbivore and disease damage on some crops, supporting our prediction that habitat heterogeneity at both local and landscape scales lowers plant damage. Greater temperature variability related to higher disease damage on tomatoes linking microclimate factors to disease prevalence. Yet, local complexity factors also related to higher incidence of plant damage for other crop species, indicating variable species‐level impacts of local management factors on plant damage. By measuring the abundance of fungus‐feeding lady beetles (Psyllobora) on cucurbits, we confirmed a strong association between natural enemies and powdery mildew. We provide a case study on how changes in local to landscape‐scale factors relate to plant damage in urban agroecosystems and suggest how urban farmers and gardeners can apply this ecological knowledge to improve sustainable urban food production.

中文翻译：

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城市农业生态系统中的植物破坏因当地和景观因素而异

景观尺度局部的生物和非生物因素影响农业系统中的虫害和疾病动态。但是，相对于专注于这些驱动因素在农村农业系统中造成作物损害的重要性的研究而言，很少有研究调查食草动物昆虫和城市农业生态系统中的植物病害造成的植物损害，因此，大多数城市农民缺乏有关作物保护策略的知识。在这里，我们使用分布在城市景观中的城市农业生态系统（社区花园）中的三种常见农作物物种作为模型系统，来询问本地，景观和微气候因素如何与草食动物和病虫害相关。我们假设，在当地植被复杂度较高，景观尺度复杂度较低且温度变化较小的花园中，植物的损害较小，但是因素的重要性是针对物种和损害的。通过测量芸苔属，葫芦，番茄害虫和病虫害在整个生长季中的生长，我们证实了因素的重要性随作物种类和危害类型而变化。局部复杂性因素（例如，树木和灌木的数量）和景观复杂性（景观中自然覆盖率）都与草食动物和某些作物的病害发生率降低有关，这支持了我们的预测，即本地和景观尺度上的生境异质性都将降低植物损害。较大的温度变异性与番茄对疾病的更高危害相关，将小气候因素与疾病流行联系在一起。但是，局部复杂性因素也与其他作物物种的植物损害发生率较高有关，这表明局部管理因素对植物损害的物种水平影响各不相同。葫芦科（Psyllobora）），我们证实天敌与白粉病之间有很强的联系。我们提供了一个案例研究，说明了本地到景观尺度因素的变化如何与城市农业生态系统中的植物损害相关，并建议城市农民和园丁如何利用这种生态知识来改善可持续的城市粮食生产。