Data from: Gypsy moth herbivory induced volatiles and reduced parasite attachment to cranberry hosts

Interactions between species can have cascading effects that shape subsequent interactions. For example, herbivory can induce plant defenses that affect subsequent interactions with herbivores, pathogens, mycorrhizae, and pollinators. Parasitic plants are present in most ecosystems, and play important roles in structuring communities. However, the effects of host herbivory on parasitic plants, and the potential mechanisms underlying such effects, are not well known. We conducted a greenhouse study to ask whether gypsy moth (Lymantria dispar) damage, host cultivar, and their interaction affected preference of the stem parasite dodder (Cuscuta spp.) on cranberry hosts (Vaccinium macrocarpum). We then assessed the mechanisms that could underlie such effects by measuring induced changes in phytohormones and secondary compounds. We found that damage by gypsy moths delayed dodder attachment by approximately 0.3 days when dodder stems were added 2 days after damage, and reduced attachment by more than 50% when dodder stems were added 1 week after host plant damage. Gypsy moth damage significantly increased jasmonic acid (JA) levels, total volatile emissions, and the flavonol, quercetin aglycone, suggesting possible mechanisms underlying variation in dodder ability to locate or attach to hosts. Dodder preference also differed between cranberry cultivars, with the highest attachment on the cultivar that had significantly lower levels of total volatile emissions and total phenolic acids, suggesting that volatile composition and phenolics may mediate dodder preference. Our results indicate that herbivory can reduce subsequent attachment by a highly damaging parasitic plant, demonstrating the potential importance of early damage for shaping subsequent species interactions.

物种间的相互作用可产生级联效应，进而塑造后续的物种互作关系。例如，植食作用可诱导植物产生防御反应，进而影响其后续与植食者、病原菌、菌根以及传粉者的相互作用。多数生态系统中均存在寄生植物，它们在群落结构构建中发挥着重要作用。然而，宿主植食作用对寄生植物的影响及其潜在作用机制，目前仍未得到充分阐明。本研究开展温室实验，探究舞毒蛾（Lymantria dispar）取食为害、宿主品种及其交互作用是否会影响茎寄生植物菟丝子（Cuscuta spp.）对蔓越莓宿主（Vaccinium macrocarpum）的选择偏好。随后，我们通过检测植物激素与次生代谢产物的诱导变化，解析了可能介导上述效应的作用机制。研究结果显示：当菟丝子茎段在宿主受舞毒蛾为害2天后接入时，舞毒蛾为害会使菟丝子的附着时间延迟约0.3天；而当菟丝子茎段在宿主受为害1周后接入时，其附着率可降低50%以上。舞毒蛾为害可显著提升宿主的茉莉酸（JA）水平、总挥发性挥发物释放量以及黄酮醇类物质槲皮素苷元的含量，这提示了菟丝子定位或附着宿主能力差异背后的潜在作用机制。不同蔓越莓品种的菟丝子附着偏好也存在显著差异：菟丝子在总挥发性挥发物与总酚酸含量显著更低的品种上附着率最高，这表明挥发性成分与酚类物质可能介导了菟丝子的宿主选择偏好。本研究结果表明，植食作用可降低后续高破坏性寄生植物的附着能力，证实了早期植食为害在塑造后续物种互作关系中的潜在重要性。