Department of Ecology and Evolutionary Biology, Cornell University, Corson Hall, Ithaca, NY, 14853, USA.
Oecologia. 2013 Dec;173(4):1387-96. doi: 10.1007/s00442-013-2717-5. Epub 2013 Jun 27.
Plant-induced responses to multiple herbivores can mediate ecological interactions among herbivore species, thereby influencing herbivore community composition in nature. Several studies have indicated high specificity of induced responses to different herbivore species. In addition, there may be genetic variation for plant response specificity that can have significant ecological implications, by altering the competitive strength and hierarchical relationships among interacting herbivore species. However, few studies have examined whether plant populations harbor genetic variation for induction specificity. Using three distinct genotypes of Solidago altissima plants, we examined whether specialist herbivore species Dichomeris leuconotella, Microrhopala vittata, and Trirhabda virgata elicit specific induction responses from plants (specificity of elicitation), and whether induction differentially affects these herbivore species (specificity of effect). Results from bioassays and secondary metabolite analyses suggest that there is specificity of both elicitation and effect in the induced responses: D. leuconotella and M. vittata preferred and performed better on leaves damaged by conspecifics than heterospecifics, and induced qualitatively different secondary metabolite profiles. In contrast, T. virgata equally avoided but physiologically tolerated all types of damage. These patterns of specificity suggest that plant-induced responses mediate asymmetric competitive interactions between herbivore species, which potentially intensifies inter-specific relative to intra-specific competition. Plant genotypes widely differed in overall susceptibility to the herbivores and secondary metabolite production, yet we found no genotype-by-treatment interactions in insect performance, preference and plant secondary metabolite production. This lack of genetic variation for induction specificity suggests that competitive interactions between herbivore species on S. altissima are homogeneous across plant genotypes.
植物对多种草食动物的诱导反应可以调节草食动物种间的生态相互作用，从而影响自然界中草食动物群落的组成。多项研究表明，诱导反应对不同草食动物种具有高度特异性。此外，植物对诱导反应的特异性可能存在遗传变异，这种遗传变异会通过改变相互作用的草食动物种之间的竞争强度和层次关系而产生重要的生态影响。然而，很少有研究检验植物种群是否具有诱导特异性的遗传变异。我们使用三种不同基因型的紫菀属植物，检验了专食性草食动物种二斑叶螨、微红沫蝉和黑缘红瓢虫是否会引起植物产生特异性诱导反应（诱导的特异性），以及诱导反应是否会对这些草食动物种产生特异性影响（效应的特异性）。生物测定和次生代谢物分析的结果表明，在诱导反应中存在诱导的特异性和效应的特异性：二斑叶螨和微红沫蝉更喜欢并在同种个体造成的叶片损伤上表现更好，而不是异种个体造成的叶片损伤，且诱导产生了不同的次生代谢物图谱。相比之下，黑缘红瓢虫同等地回避但在生理上容忍所有类型的损伤。这些特异性模式表明，植物诱导反应介导了草食动物种之间的不对称竞争相互作用，这种相互作用可能会加剧种间相对种内的竞争。植物基因型在对草食动物的整体易感性和次生代谢产物的产生方面广泛存在差异，但我们在昆虫表现、偏好和植物次生代谢产物产生方面没有发现处理与基因型的互作。这种诱导特异性的遗传变异缺乏表明，在紫菀属植物上，草食动物种之间的竞争相互作用在不同的植物基因型中是同质的。
