Université Côte d'Azur, INRAE, CNRS, UMR ISA, 06000 Nice, France.
Université Côte d'Azur, INRAE, CNRS, UMR ISA, 06000 Nice, France.
Sci Total Environ. 2021 Nov 1;793:148544. doi: 10.1016/j.scitotenv.2021.148544. Epub 2021 Jun 19.
Nitrogen (N) and water are crucial in crop production but increasingly scarce environmental resources. Reducing their inputs can affect the whole plant-arthropod community including biocontrol agents. In a multitrophic system, we studied the interaction of the bottom-up effects of moderately reduced N concentration and/or water supply as well as the top-down effects of pests of different feeding guilds on plant nutritional quality (N and carbon concentration), direct defense (alkaloids and phenolics), and indirect defense (plant volatile organic compounds); on herbivore performance and host quality (N and carbon) to parasitoids and the latter's performance. Studied organisms were tomato plants, the sap feeders Macrosiphum euphorbiae and Bemisia tabaci, the leaf chewers Tuta absoluta and Spodoptera littoralis, and the parasitic wasps Aphelinus abdominalis and Necremnus tutae. Resource limitation affected plant quality, triggering bottom-up effects on herbivore and parasitoid performance, except for T. absoluta and N. tutae. Feeding guild had a major influence: bottom-up effects were stronger on sap feeders; N effects were stronger on sap feeders while water effects were stronger with leaf chewers (S. littoralis). Top-down effects of leaf chewer herbivory partly attenuated bottom-up effects and partly suppressed plant defenses. Bottom-up effects weakened when cascading up trophic levels. In summary, the interaction between plants, pests, and beneficial insects was modulated by abiotic factors, affecting insect performance. Simultaneous abiotic and biotic impact shaped plant biochemistry depending on the feeding guild: the biotic top-down effect of leaf chewer herbivory attenuated the bottom-up effects of plant nutrition and hence dominated the plant biochemical profile whereas in sap feeder infested leaves, it corresponded to the abiotic impact. This study highlights the plant's finely tuned regulatory system facilitating response prioritization. It offers perspectives on how smart manipulation of plant nutrient solutions might save resources while maintaining efficient biocontrol in crop production.
氮（N）和水是作物生产中至关重要的资源，但它们在环境中日益稀缺。减少这些投入可能会影响整个植物-节肢动物群落，包括生物防治剂。在一个多营养层次系统中，我们研究了中度降低 N 浓度和/或供水的自上而下的影响以及不同取食群体的害虫的自上而下的影响对植物营养质量（N 和碳浓度）、直接防御（生物碱和酚类）和间接防御（植物挥发性有机化合物）的影响；对草食动物的表现和对寄生蜂的寄主质量（N 和碳）的影响，以及后者的表现。研究的生物是番茄植物、刺吸式口器的麦长管蚜和烟粉虱、咀嚼式口器的烟实夜蛾和斜纹夜蛾，以及寄生蜂金小蜂和暗黑赤眼蜂。资源限制影响植物质量，引发对草食动物和寄生蜂表现的自上而下的影响，但烟实夜蛾和暗黑赤眼蜂除外。取食群体有重大影响：对刺吸式口器的自上而下的影响更强；N 对刺吸式口器的影响更强，而水对咀嚼式口器的影响更强（斜纹夜蛾）。咀嚼式口器的食叶性害虫取食的自上而下的影响部分减弱了自上而下的影响，并部分抑制了植物防御。当营养层次级联时，自上而下的影响减弱。总之，植物、害虫和有益昆虫之间的相互作用受到非生物因素的调节，影响昆虫的表现。同时受到非生物和生物的影响取决于取食群体：食叶性害虫的生物性自上而下的影响减弱了植物营养的自上而下的影响，因此主导了植物的生化特征，而在刺吸式口器为害的叶片中，它与非生物影响相对应。这项研究强调了植物精细调节系统促进了响应的优先级。它提供了关于如何通过智能操纵植物营养液来节约资源，同时在作物生产中保持高效生物防治的观点。
