Insect chemosensation is crucial for many aspects related to food seeking, enemy avoidance, and reproduction. Different families of receptors and binding proteins interact with chemical stimuli, including odorant receptors (ORs), ionotropic receptors (IRs), gustatory receptors (GRs), odorant binding proteins (OBPs) and chemosensory proteins (CSPs). In this work, we describe the chemosensory-related gene repertoire of the worldwide pest Spodoptera exigua (Lepidoptera: Noctuidae), focusing on the transcripts expressed in larvae, which feed on many horticultural crops producing yield losses. A comprehensive de novo assembly that includes reads from chemosensory organs of larvae and adults, and other larval tissues, enabled us to annotate 200 candidate chemosensory-related genes encoding 63 ORs, 28 IRs, 38 GRs, 48 OBPs and 23 CSPs. Of them, 51 transcripts are new annotations. Fifty ORs are expressed in larval heads based on RNA-seq and reverse transcription PCR analyses. Fourteen OBPs are expressed in larval, but not in adult heads. We also observe that expression profiles of ORs are strongly and non-specifically up-regulated upon pre-exposure of larvae to single volatile organic compounds (VOCs). Finally, we develop a behavioural assay to study the attraction/repellence to VOCs in S. exigua larvae and thus identify candidate ecologically relevant odours. A single-dose assay demonstrated that 1-hexanol triggers attraction and indole repels larvae at any timepoint. This work establishes the foundation for the study of chemosensation in S. exigua larvae, allowing further studies aimed to characterize chemosensory-related genes that underlie the ecologically relevant behaviours of larvae.

昆虫化学传感对于与觅食，躲避敌人和繁殖有关的许多方面至关重要。受体和结合蛋白的不同家族与化学刺激物相互作用，包括气味受体（OR），离子型受体（IR），味觉受体（GR），气味结合蛋白（OBP）和化学感觉蛋白（CSP）。在这项工作中，我们描述了全世界害虫夜蛾（Spodoptera exigua）（鳞翅目：夜蛾科）的化学感官相关基因库，着重于幼虫中表达的转录本，这些转录本以许多园艺作物为食，导致产量下降。全面的从头包括从幼虫和成人的化学感应器官以及其他幼虫组织读取的装配，使我们能够注释200个候选化学感应相关基因，这些基因编码63个OR，28个IR，38个GR，48个OBP和23个CSP。其中，有51个笔录是新的注释。根据RNA-seq和逆转录PCR分析，在幼虫头部表达五十个OR。在幼虫中表达了十四种OBP，但在成年头中则没有。我们还观察到，在幼虫预先暴露于单一挥发性有机化合物（VOC）后，OR的表达谱强烈且非特异性上调。最后，我们开发了一种行为分析方法，以研究对S. exigua的VOC的吸引/排斥幼虫，从而识别出与生态相关的候选气味。单剂量试验表明1-己醇可在任何时间点触发吸引力，并吲哚排斥幼虫。这项工作为研究S. exigua幼虫的化学感觉奠定了基础，允许进行进一步的研究，以鉴定与幼虫的生态相关行为相关的化学感应相关基因。