Chemical cues linked to risk: cues from belowground natural enemies enhance plant defences and influence herbivore behaviour and performance

1. Chemical cues are essential for many ecological interactions. Previous studies of chemically mediated multitrophic interactions have typically focused on responses to cues from plants or herbivores aboveground. It is increasingly clear, however, that belowground cues and those produced by organisms at higher trophic levels also have ecological importance. Prey animals often avoid predator odours to improve survival, and previous research documented enhanced plant resistance following contact with belowground natural enemies, though the ecological basis was unknown. 2. Here we investigated plant and insect responses to chemical cues from belowground natural enemies and explored the ecological significance of these cues for multitrophic interactions. More specifically, we examined the influence of odours emitted by entomopathogenic nematodes (EPNs), a natural enemy of insect herbivores, on the performance and behaviour of their insect prey and the defence responses of nearby plants....1. 化学信号（chemical cues）对诸多生态互作至关重要。此前针对化学介导多营养级互作的研究，多聚焦于地上植物或植食性昆虫释放的信号所引发的生物响应。但愈来愈多的研究证实，地下信号以及高营养级生物产生的信号同样具有重要生态意义。猎物动物常通过规避捕食者释放的气味来提升生存概率；既往研究曾记录植物接触地下天敌后抗性增强的现象，但其背后的生态机制尚未明确。 2. 本研究针对植物与昆虫对地下天敌释放的化学信号的响应展开探究，并解析了此类信号在多营养级互作中的生态意义。具体而言，我们考察了昆虫病原线虫（entomopathogenic nematodes, EPNs，植食性昆虫的天敌）释放的气味，对其猎物昆虫的生长表现与行为，以及邻近植物防御响应的影响。