Milano N J, Barber N A, Adler L S
Department of Biology, University of Massachusetts-Amherst, 611 North Pleasant St., Amherst, MA 01003.
Department of Biological Sciences, Northern Illinois University, 155 Castle Dr., DeKalb, IL 60115.
Environ Entomol. 2015 Apr;44(2):317-24. doi: 10.1093/ee/nvv003. Epub 2015 Feb 26.
Insect herbivores damage plants both above- and belowground, and interactions in each realm can influence the other via shared hosts. While effects of leaf damage on aboveground interactions have been well-documented, studies examining leaf damage effects on belowground interactions are limited, and mechanisms for these indirect interactions are poorly understood. We examined how leaf herbivory affects preference of root-feeding larvae [Acalymma vittatum F. (Coleoptera: Chrysomelidae)] in cucumber (Cucumis sativus L.). We manipulated leaf herbivory using conspecific adult A. vittatum and heterospecific larval Spodoptera frugiperda Smith (Lepidoptera: Noctuidae) herbivores in the greenhouse and the conspecific only in the field, allowing larvae to choose between roots of damaged and undamaged plants. We also examined whether leaf herbivory induced changes in defensive cucurbitacin C in leaves and roots. We hypothesized that induced changes in roots would deter larvae, and that effects would be stronger for damage by conspecifics than the unrelated caterpillar because the aboveground damage could be a cue to plants indicating future root damage by the same species. In both the greenhouse and field, plants with damaged leaves recruited significantly fewer larvae to their roots than undamaged plants. Effects of conspecific and heterospecific damage did not differ. Leaf damage did not induce changes in leaf or root cucurbitacin C, but did reduce root biomass. While past work has suggested that systemic induction by aboveground herbivory increases resistance in roots, our results suggest that decreased preference by belowground herbivores in this system may be because of reduced root growth.
植食性昆虫会对植物地上和地下部分造成损害，并且每个领域的相互作用都可以通过共享宿主影响另一个领域。虽然叶片损伤对地上相互作用的影响已有充分记录，但研究叶片损伤对地下相互作用影响的研究有限，而且这些间接相互作用的机制也知之甚少。我们研究了叶片取食如何影响黄瓜（Cucumis sativus L.）中取食根部的幼虫[Acalymma vittatum F.（鞘翅目：叶甲科）]的偏好。我们在温室中使用同种成年A. vittatum和异种幼虫草地贪夜蛾Spodoptera frugiperda Smith（鳞翅目：夜蛾科）食草动物来操纵叶片取食，在田间仅使用同种食草动物，让幼虫在受损和未受损植物的根之间进行选择。我们还研究了叶片取食是否会诱导叶片和根中防御性葫芦素C的变化。我们假设根部的诱导变化会阻止幼虫，并且同种造成的损害比无关毛虫造成的影响更强，因为地上损害可能是植物表明未来会受到同一物种根部损害的线索。在温室和田间，叶片受损的植物根部吸引的幼虫数量均显著少于未受损植物。同种和异种损害的影响没有差异。叶片损伤并未诱导叶片或根中葫芦素C的变化，但确实降低了根生物量。虽然过去的研究表明地上食草动物的系统诱导会增加根部的抗性，但我们的结果表明，在这个系统中地下食草动物偏好降低可能是由于根生长减少。
