In insects, neuropeptides regulate numerous biological processes, including development, growth, reproduction, metabolism, and behavior. The physiological role of Trissin, an insect neuropeptide, is poorly known. Studies on Drosophila melanogaster have shown that Trissin is involved in muscle activity and contractions in the foregut, food intake, and regulating digestive processes. Trissin activates G-protein coupled receptors (GPCRs), cell surface receptors that detect external signals and interact with G-proteins to initiate intracellular signal transduction. Trissin Receptor-like (TRL), a GPCR activated by the Trissin peptide in vitro, facilitates nutrient uptake in the foregut by increasing intracellular calcium ion levels. In this study, we investigated the physiological role of the Trissin Receptor-like (LdTRL) in the initiation and maintenance of diapause in the Colorado potato beetle (Leptinotarsa decemlineata), a major pest of Solanaceae plants worldwide. Our findings revealed that LdTRL expression levels increased during diapause. Using RNA interference (RNAi) to silence the LdTRL, we observed a nearly 50% mortality rate during diapause, highlighting the critical role of this gene in the diapause phase. Interestingly, silencing LdTRL did not affect the fertility and fecundity of the Colorado potato beetles, indicating that LdTRL does not affect reproductive capabilities while it is essential for diapause survival. These findings suggest that Trissin Receptor-like is a key factor in initiating and maintaining diapause in L. decemlineata; however, further studies are needed to elucidate its precise role in the Colorado potato beetle.
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