Grosjean Jeremy, Pashalidou Foteini G, Fauvet Aude, Baillet Aurore, Kergunteuil Alan
Université de Lorraine, LAE, INRAE, 54000 Nancy, France.
Platform of Structural and Metabolomics Analyses, SF4242, EFABA, Lorraine University, Vandoeuvre-les-Nancy, France.
R Soc Open Sci. 2024 Jul 17;11(7):240890. doi: 10.1098/rsos.240890. eCollection 2024 Jul.
Plant metabolism is a key feature of biodiversity that remains underexploited in functional frameworks used in agroecology. Here, we study how phytochemical diversity considered at three organizational levels can promote pest control. In a factorial field experiment, we manipulated plant diversity in three monocultures and three mixed crops of oilseed rape to explore how intra- and interspecific phytochemical diversity affects pest infestation. We combined recent progress in metabolomics with classic metrics used in ecology to test a box of hypotheses grounded in plant defence theory. According to the hypothesis of 'phytochemically mediated coevolution', our study stresses the relationships between herbivore infestation and particular classes of specialized metabolites like glucosinolates. Among 178 significant relationships between metabolites and herbivory rates, only 20% were negative. At the plant level, phytochemical abundance and richness had poor predictive power on pest regulation. This challenges the hypothesis of 'synergistic effects. At the crop cover level, in line with the hypothesis of 'associational resistance', the phytochemical dissimilarity between neighbouring plants limited pest infestation. We discuss the intricate links between associational resistance and bottom-up pest control. Bridging different levels of organization in agroecosystems helps to dissect the multi-scale relationships between phytochemistry and insect herbivory.
植物代谢是生物多样性的一个关键特征，但在农业生态学的功能框架中仍未得到充分利用。在这里，我们研究了在三个组织水平上考虑的植物化学多样性如何促进害虫控制。在一项析因田间试验中，我们对三种单作和三种油菜混合作物中的植物多样性进行了调控，以探究种内和种间植物化学多样性如何影响害虫侵袭。我们将代谢组学的最新进展与生态学中使用的经典指标相结合，以检验一系列基于植物防御理论的假设。根据“植物化学介导的协同进化”假说，我们的研究强调了食草动物侵袭与特定类别的特殊代谢产物（如芥子油苷）之间的关系。在代谢产物与食草率之间的178个显著关系中，只有20%是负相关的。在植物水平上，植物化学物质的丰度和丰富度对害虫调控的预测能力较差。这对“协同效应”假说提出了挑战。在作物覆盖水平上，与“联合抗性”假说一致，相邻植物之间的植物化学差异限制了害虫侵袭。我们讨论了联合抗性与自下而上的害虫控制之间的复杂联系。弥合农业生态系统中不同组织水平之间的差距有助于剖析植物化学与昆虫食草作用之间的多尺度关系。
