De novo transcriptome sequencing to identify the neuropeptides and neuropeptide receptors of the paulownia bagworm <i>Clania variegata</i> (Lepidoptera: Psychidae)

In insects, neuropeptides are important signal molecules, mainly synthesized and released from neurosecretory cells within the central nervous system. Neuropeptides regulate multiple behavioral and physiological processes by acting on their corresponding receptors and are increasingly being considered as targets for new environmentally friendly insecticides. In this study, RNA-seq technology and bioinformatics were used to explore neuropeptides and their receptors by comparing the transcriptome profiles of the larval heads of male and female Clania variegata Snellen (Lepidoptera: Psychidae), a pest with significant agricultural and ecological impact. The clean transcriptome reads were assembled into 41,283 unigenes, with 2,461 differently expressed genes (DEGs) between the male and female groups. Fourteen neuropeptides were identified, of which allatotropin, allatostatin, and eclosion hormone can be used as potential pest control agents based on their pivotal roles in regulating growth and development. Several amidated neuropeptides were also identified, including neuropeptide IMFamide, myosuppressin-like isoform X2, neuropeptide F, short neuropeptide F, FMRFamide-related peptides, and CCHamide-2 isoform X2. Additionally, neuropeptides such as ion transport peptide-like, diuretic hormone class 2, diuretic hormone 41 isoform X4, and pro-corazonin are believed to regulate ion and water balance through modulation of the excretory system. Fifteen neuropeptide receptors were found, including those for allatostatin-A, neuropeptide CCHamide-2, neuropeptide F, FMRFamide, and neuropeptide SIFamide, several of which are implicated in behavioral regulation. However, no significant differences in neuropeptide or receptor expression were observed between sexes. These results enrich the neuropeptide gene database and offer insights into the neuropeptidergic signaling system in C. variegata.