Lepidoptera (moths and butterflies) and Trichoptera (caddisflies), belonging to the superorder Amphiesmenoptera, are the most diverse insect orders as representatives of the terrestrial and aquatic insects, respectively. The insects of the two orders possess different biological and behavioral characteristics, especially their larvae, presumably resulting in the differences of the ionotropic receptor (IR) genes in numbers, sequence characteristics or gene structure. Here, we employed genomics, transcriptomics, bioinformatics, phylogenetics and molecular biology strategies to characterize the IR gene repertoire in Lepidoptera and Trichoptera. Genome and transcriptome analyses with exhaustive homology-based searches and manual efforts, in 32 lepidopterans and five trichopterans, led to the identification of 1449 genes encoding IRs with 1170 full-length sequences, representing the most comprehensive set of chemoreceptor superfamilies across the Amphiesmenoptera. Analysis of gene gains and losses in orthologous groups implied that some IRs were lost in related species, and multiple gene copies occurred mainly in divergent IRs (D-IRs) by gene duplications. Phylogenetic analysis of 2442 IR proteins from 67 species revealed that Lepidoptera and Trichoptera IRs could be classified into three subfamilies, i.e., 14 antennal IRs (A-IRs), five Lepidoptera-specific IRs (LS-IRs) and four D-IRs. Of the three subfamilies, A-IRs and LS-IRs members within orthologous groups exhibited high conservation of gene structure, but D-IRs shared extremely low amino acid identities (below 30%). Expression profiles revealed functional diversities of IRs from Bombyx mori and Papilio xuthus involving smell, taste or reproduction, in which some genes displayed sex-biased expression in antennae associated with specific chemosensory behaviors of female or male adults. Our current study has provided insights into the evolution, conservation and divergence of IRs between/within Lepidoptera and Trichoptera, and allows for further experiments to investigate IR functions.

鳞翅目（飞蛾和蝴蝶）和毛翅目（caddisflies）属于双翅目超目，分别是陆生昆虫和水生昆虫的代表，是最多样化的昆虫目。这两个目昆虫具有不同的生物学和行为特征，尤其是它们的幼虫，推测是导致离子型受体（IR）基因在数量、序列特征或基因结构上的差异。在这里，我们采用基因组学、转录组学、生物信息学、系统发育学和分子生物学策略来表征鳞翅目和毛翅目中的 IR 基因库。通过详尽的基于同源性的搜索和手动操作对 32 种鳞翅目动物和 5 种三翅目动物进行基因组和转录组分析，导致鉴定出编码具有 1170 个全长序列的 IR 的 1449 个基因，代表了跨翅目最全面的化学感受器超家族。对直系同源群体中基因得失的分析表明，一些IR在相关物种中丢失，并且多个基因拷贝主要发生在通过基因复制的发散IR（D-IR）中。来自67个物种的2442个IR蛋白的系统发育分析表明，鳞翅目和毛翅目IRs可分为三个亚科，即14个触角IRs（A-IRs）、5个鳞翅目特异性IRs（LS-IRs）和4个D-IRs。在三个亚科中，直系同源组中的 A-IR 和 LS-IR 成员表现出高度的基因结构保守性，但 D-IR 具有极低的氨基酸同一性（低于 30%）。Bombyx mori和Papilio xuthus涉及嗅觉、味觉或繁殖，其中一些基因在触角中表现出与雌性或雄性成年人的特定化学感应行为相关的性别偏见表达。我们目前的研究提供了对鳞翅目和毛翅目之间/内部 IR 的进化、保护和分歧的见解，并允许进一步的实验来研究 IR 功能。