Davidson-Lowe Elizabeth, Zainuddin Nursyafiqi, Trase Olivia, McCarthy Nathaniel, Ali Jared Gregory
Center for Chemical Ecology, The Pennsylvania State University, University Park, PA 16802, USA.
Center for Chemical Ecology, The Pennsylvania State University, University Park, PA 16802, USA; Department of Plant Protection, University Putra Malaysia, 43400 Serdang, Selangor, Malaysia.
J Invertebr Pathol. 2024 Nov;207:108200. doi: 10.1016/j.jip.2024.108200. Epub 2024 Oct 5.
As primary producers, plants play a central role in mediating interactions across trophic levels. Although plants are the primary food source for herbivorous insects, they can protect themselves from herbivore damage. Many plants produce toxic compounds that directly reduce herbivore feeding, but plants also protect themselves indirectly by attracting natural enemies of the attacking herbivore through volatile signaling. These so-called tri-trophic interactions have historically been documented aboveground in aerial plant parts but are also known to occur belowground in root systems. In addition to herbivores, plants directly interact with other organisms, which can influence the outcomes of tri-trophic interactions. Arbuscular mycorrhizal fungi (AMF) are symbiotic soil microbes that colonize the roots of plants and facilitate nutrient uptake. These microbes can alter plant chemistry and subsequent resistance to herbivores. Few studies, however, have shown how AMF affect tri-trophic interactions above- or belowground. This study examines how AMF colonization affects the emission of root volatiles when plants are under attack by western corn rootworm, a problematic pest of corn, and subsequent attraction of entomopathogenic nematodes, a natural enemy of western corn rootworm. Mycorrhizal fungi increased rootworm survival but decreased larval weight. Differences were detected across root volatile profiles, but there was not a clear link between volatile signaling and nematode behavior. Nematodes were more attracted to non-mycorrhizal plants without rootworms and AMF alone in soil, suggesting that AMF may interfere with cues that are used in combination with volatiles which nematodes use to locate prey.
作为初级生产者，植物在介导不同营养级之间的相互作用中起着核心作用。尽管植物是食草昆虫的主要食物来源，但它们能够保护自己免受食草动物的侵害。许多植物会产生有毒化合物，直接减少食草动物的取食，而且植物还通过挥发性信号吸引攻击它们的食草动物的天敌来间接保护自己。这些所谓的三级营养相互作用在历史上已在地上部分的气生植物器官中得到记载，但也已知在地下的根系中发生。除了食草动物外，植物还与其他生物体直接相互作用，这可能会影响三级营养相互作用的结果。丛枝菌根真菌（AMF）是共生土壤微生物，它们定殖在植物根系中并促进养分吸收。这些微生物可以改变植物的化学成分以及随后对食草动物的抗性。然而，很少有研究表明AMF如何影响地上或地下的三级营养相互作用。本研究考察了在玉米的一种害虫西部玉米根虫攻击植物时，AMF定殖如何影响根系挥发物的释放，以及随后对西部玉米根虫的天敌昆虫病原线虫的吸引。菌根真菌提高了根虫的存活率，但降低了幼虫体重。在根系挥发物谱中检测到了差异，但挥发性信号与线虫行为之间没有明确的联系。线虫对没有根虫的非菌根植物以及单独存在于土壤中的AMF更有吸引力，这表明AMF可能会干扰线虫用来定位猎物的与挥发物结合使用的线索。
