Urban tree pests can support biological control services in landscape shrubs

Scale insects are common tree pests in urban ecosystems. Although severe scale infestations can worsen tree condition, trees can tolerate moderate scale densities. Scale insects are prey for many arthropod natural enemies that also feed on plant pests throughout urban landscapes. Because scale-infested trees support natural enemy communities, they may support biological control services on nearby plants and function analogously to banker plants in greenhouse production systems. In this study, we tested if sentinel insect prey were more likely to be removed on shrubs below scale-infested trees compared to scale-uninfested trees. We conducted several biological control experiments from 2019–2021 using fruit flies, aphids, and caterpillars in potted and planted holly shrubs below scale-infested and scale-uninfested oak trees. We found that caterpillars in potted shrubs and fruit flies in planted landscape shrubs were more likely to be removed underneath scale-infested trees compared to sca..., ,

介壳虫（Scale insects）是城市生态系统中常见的林木害虫。尽管严重的介壳虫侵染会恶化林木健康状况，但树木可耐受中等密度的介壳虫种群。介壳虫是多种节肢动物天敌的猎物，这类天敌在城市园林景观中同样以植物害虫为食。由于受介壳虫侵染的林木可支撑天敌群落，因此它们可为周边植物提供生物防治服务，其功能与温室生产系统中的保育植物（banker plants）类似。本研究旨在验证：相较于未受介壳虫侵染的林木，介壳虫侵染林木下方的灌木上的哨兵昆虫猎物（sentinel insect prey）是否更易被移除。本研究于2019年至2021年间开展了多组生物防治实验，以实蝇、蚜虫与毛虫为实验材料，在受介壳虫侵染与未受侵染的栎树下方的盆栽及定植冬青灌木中进行实验。我们发现，盆栽灌木中的毛虫以及定植园林灌木中的实蝇，在介壳虫侵染的栎树下方的移除率显著高于未受介壳虫侵染的树木（原文此处内容截断）