Data from: Local and landscape drivers of predation services in urban gardens

In agroecosystems, local and landscape features, as well as natural enemy abundance and richness are significant predictors of predation services that may result in biological control of pests. Despite the increasing importance of urban gardening for provisioning of food to urban populations, most urban gardeners suffer from high pest problems, and have little knowledge about how to manage their plots to increase biological control services. We examined the influence of local, garden scale (i.e. herbaceous and arboreal vegetation abundance and diversity, ground cover) and landscape (i.e. landscape diversity and surrounding land use types) characteristics on predation services provided by naturally occurring predators in 19 urban gardens in the California central coast. We introduced sentinel pests (moth eggs and larvae and pea aphids) onto greenhouse-raised plants taken to gardens and assigned to open or bagged (predator exclosure) treatments. We found high predation rates with between 40-90% of prey items removed in open treatments. Predation services varied with local and landscape factors, but significant predictors differed by prey species. Predation of eggs and aphids increased with vegetation complexity in gardens, but larvae predation declined with vegetation complexity. Smaller gardens experienced higher predation services, likely due to increases in predator abundance in smaller gardens. Several ground cover features influenced predation services. In contrast to patterns in rural agricultural landscapes, predation on aphids declined with increases in landscape diversity. In sum, we report the relationships between several local management factors, as well as landscape surroundings, and implications for garden management.在农业生态系统（agroecosystems）中，局地与景观特征，以及天敌丰度和物种丰富度，是捕食服务（predation services）的显著预测因子，而此类捕食服务可实现害虫的生物防治（biological control）。尽管都市园艺（urban gardening）为城市人口提供食物的重要性与日俱增，但多数都市园艺从业者仍面临严重的虫害问题，且对如何优化种植地块管理以增强生物防治服务知之甚少。我们针对加州中部海岸的19座都市园艺场开展研究，探究局地尺度（即草本与木本植被的丰度、多样性以及地表覆盖）和景观尺度（即景观多样性与周边土地利用类型）的特征对自然捕食者所提供的捕食服务的影响。我们将温室培育植株移栽至各园艺场，在植株上接种指示害虫（sentinel pests）——包括蛾卵、幼虫与豌豆蚜（pea aphids），并设置两种处理组：开放式（允许天敌访问）与套袋（天敌排除（predator exclosure））。我们发现开放式处理组的猎物移除率达40%~90%，捕食率较高。捕食服务随局地与景观因子发生变化，但关键预测因子因猎物物种而异：蛾卵与豌豆蚜的捕食率随园艺场植被复杂度提升而升高，而幼虫捕食率则随植被复杂度提升而降低。面积较小的园艺场捕食服务更强，这可能与小型园艺场中天敌丰度更高有关。多项地表覆盖特征亦对捕食服务产生影响。与农田生态系统的相关规律不同，豌豆蚜的捕食率随景观多样性提升而降低。综上，本研究阐明了多项局地管理因子、景观环境与捕食服务间的关联，并探讨了其对都市园艺管理的启示。