Data from: Salicylate plant defenses reduce aphid nutritional quality and increase predator consumption

Plant-induced defenses can shape multitrophic interactions by affecting
herbivore performance and altering their suitability as prey. While the
direct effects of these defenses on herbivores are well documented, their
indirect consequences— particularly for predator behavior and biological
control effectiveness— remain less understood. In our study, we examined
how activating salicylic acid (SA)-mediated defenses in tomato plants
affects the performance and nutritional quality of the
aphid, Macrosiphum euphorbiae, and how this intraspecific
variation in aphid quality as prey impacts the predation by the lady
beetle predator, Hippodamia convergens. Aphids on SA-treated plants
exhibited reduced body mass, protein, and lipid content, indicating lower
nutritional value as prey. Correspondingly, we recorded a stronger decline
in aphid population on SA-treated plants in the presence of predators. To
investigate the effects of reduced aphid quality on predation, we
conducted a controlled no-choice assay, which showed that individual lady
beetle predators consume more aphids from the SA-treated plants. This
increased consumption is consistent with compensatory feeding in response
to nutrient-poor prey, although alternative explanations, such as
increased prey vulnerability, should also be considered. Our findings
demonstrate that SA-mediated defenses can shape predator-prey interactions
through bottom-up effects on prey quality and underscore the need to
consider these cascading effects when evaluating the ecological impact of
plant resistance traits in biological control strategies.

植物诱导防御（plant-induced defenses）可通过影响植食性昆虫的生长表现、改变其作为猎物的适宜性，调控多营养级互作（multitrophic interactions）。尽管这类防御对植食性昆虫的直接效应已有充分文献记载，但其间接后果——尤其是对捕食者行为与生物防治（biological control）效能的影响——仍未得到充分解析。本研究探讨了番茄植株中水杨酸（salicylic acid, SA）介导的防御激活，如何影响蚜虫（Macrosiphum euphorbiae）的生长表现与营养品质，以及这种猎物品质的种内变异如何对捕食性瓢虫（Hippodamia convergens）的捕食行为产生影响。取食经SA处理的番茄植株的蚜虫，其体重、蛋白质与脂质含量均显著降低，表明其作为猎物的营养价值有所下降。相应地，在捕食者存在的情况下，SA处理组植株上的蚜虫种群数量下降更为显著。为探究蚜虫营养品质下降对捕食行为的影响，我们开展了严格的非选择性饲喂试验，结果显示单头捕食性瓢虫取食SA处理组植株上的蚜虫数量更多。这一捕食量增加的现象符合猎物营养匮乏时的补偿性取食（compensatory feeding）规律，但也需考虑其他潜在解释，例如猎物被捕食的易感性提升。本研究结果表明，SA介导的植物防御可通过上行效应（bottom-up effects）改变猎物品质，进而调控捕食者-猎物互作（predator-prey interactions），这提示在评估植物抗性性状对生物防治策略的生态效应时，需纳入这类级联效应的考量。