Scale insects support natural enemies in both landscape trees and shrubs below them

Scale insects are frequently abundant on urban trees. Although scales can worsen tree condition, some tree species tolerate moderate scale densities. Scales are prey for many natural enemies. Therefore, scale-infested trees may conserve natural enemies in their canopies and in nearby plants. We examined if scale-infested oaks—Quercus phellos L.—hosted more natural enemies than scale-uninfested oaks—Q. acutissima Carruth. and Q. lyrata Walter in Raleigh, NC. USA. We also tested if natural enemies were more abundant in holly shrubs (Ilex spp.) planted below scale-infested compared to scale-uninfested oaks. We collected natural enemies from the canopies of both tree types and from holly shrubs planted below these trees. To determine if tree type affected the abundance of natural enemies that passively dispersed to shrubs, we created hanging cup traps to collect arthropods as they fell from trees. To determine if enemies became more abundant on shrubs below scale-infested compared to scale-...蚧壳虫 (Scale insects) 在城市行道树上的种群密度通常较高。尽管蚧壳虫会加剧树木健康状况恶化，但部分树种可耐受中等密度的蚧壳虫种群。蚧壳虫是多种天敌昆虫的猎物，因此被蚧壳虫侵染的树木可在其树冠及周边植被中庇护天敌种群。本研究旨在检验：在美国北卡罗来纳州 (NC) 罗利市，被蚧壳虫侵染的柳叶栎 (*Quercus phellos* L.) 是否比未被侵染的麻栎 (*Q. acutissima* Carruth.) 与琴叶栎 (*Q. lyrata* Walter) 承载更多的天敌昆虫。本研究同时测试：种植于被蚧壳虫侵染的栎树下的冬青灌丛 (*Ilex* spp.) 内的天敌昆虫种群密度，是否高于种植于未被侵染栎树下的灌丛。研究人员从两类栎树的树冠以及其下方种植的冬青灌丛中采集天敌昆虫。为明确栎树种类是否会影响被动扩散至灌丛的天敌昆虫种群密度，我们设置了悬挂式捕虫杯，用于收集从树上坠落的节肢动物。为探究天敌昆虫在被蚧壳虫侵染的栎树下的灌丛中是否更为富集[原文未完整呈现后续实验内容]