Abstract

Soil abiotic stresses can trigger bottom-up effects on insect pests. However, it remains unknown whether the bottom-up effects differentially affect leaf chewers and sap-feeders, and whether abiotic stresses alter the extent of indirect interactions between insect herbivores sharing a host plant. We carried out a set of manipulative experiments to investigate how abiotic and biotic stresses affected performance associated with insect herbivory (eating by leaf chewer or sap-feeder) and plant physiological conditions (manipulating water and/or salt inputs). We examined the performance of response species (sap-feeder Macrosiphum euphorbiae and leaf chewer Tuta absoluta) on tomato plants Solanum lycopersicum that were exposed to eight conditions in a full factorial design based on (1) optimal or limited water inputs, (2) with or without 100 mM NaCl, and (3) with or without pre-infestation by insect herbivors showing distinct feeding habit. Water and salt stresses slowed down plant growth in terms of plant height and node number, which subsequently negatively affected the herbivores via bottom-up effects. Tuta absoluta larval development was adversely affected by water limitation, while M. euphorhiae survival and fertility were adversely affected by salinity stress. After pre-infestation by the inducing species (i.e. feeding activity on the plant), the test species (either M. euphorbiae or T. absoluta) exhibited a lower performance, that is, lower M. euphorbiae survival and fewer offspring, and extended T. absoluta developmental duration and reduced pupal weight. These results suggested an apparent competition between the herbivores; however, neither water limitation nor salt stress affected the magnitude of the negative indirect interactions between the two insect species. Our findings shed light on how cascading force(s) and induced indirect resistance(s) could be used to improve integrated pest management programs.

中文翻译：

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水分和盐胁迫不会触发自下而上的作用，对叶片咀嚼物和汁液喂料器之间的植物介导的间接相互作用

摘要

土壤非生物胁迫可以触发对害虫的自下而上的影响。然而，尚不清楚自下而上的影响是否会不同地影响叶片的咀嚼物和汁液供给器，以及非生物胁迫是否会改变共享寄主植物的昆虫食草动物之间的间接相互作用程度。我们进行了一组操作性实验，以研究非生物和生物胁迫如何影响与昆虫食草（由叶片咀嚼物或汁液进食器进食）和植物生理条件（控制水和/或盐输入）相关的性能。我们检查了响应物种（番茄给食茄）的反应物种（汁液喂食者Macrosiphum euphorbiae和叶咀嚼Tuta absoluta ）的性能。根据（1）最佳或有限的水输入量，（2）有或没有100 mM NaCl以及（3）有或没有预先表现出不同摄食习性的昆虫除草剂对它们进行全因子设计的八种条件。水分和盐胁迫在植物高度和节数方面减慢了植物的生长，随后通过自下而上的作用对草食动物产生了负面影响。番茄斑潜蝇幼虫的发育是由水限制的不利影响，而M. euphorhiae存活率和生育率却受到盐胁迫的影响。在诱导物种预先侵染（即对植物的摄食活性）后，测试物种（大戟莫拉氏菌或绝对黑麦草））表现出较低的性能，即较低的大戟支原体存活率和较少的后代，并延长了绝对的T.absoluta发育持续时间并降低了weight重。这些结果表明食草动物之间存在明显的竞争。但是，水分限制和盐胁迫都不会影响这两种昆虫之间负向间接相互作用的程度。我们的发现揭示了如何利用级联力和诱导的间接抗性来改善病虫害综合防治计划。