Transcriptome analysis in red palm weevil (Rhynchophorus ferrugineus Olivier) larvae in response to low temperatures

Abstract

The red palm weevil (RPW), Rhynchophorus ferrugineus, is one of the most destructive palm pests worldwide. Despite its tropical origin, this species tolerates moderately low temperatures and therefore has an expansion potential that may be enhanced by global warming. However, the molecular mechanisms underlying this cold tolerance remain poorly understood. This study provides the first comprehensive transcriptomic analysis of the RPW’s response to cold stress. Using RNA-Seq on RPW larvae exposed for seven days to either a sublethal low temperature (5°C) or control conditions (23°C), we identified 701 differentially expressed unigenes (580 protein-coding genes, 81 lncRNAs, and 40 transposable element–associated transcripts), of which 448 were upregulated and 253 downregulated under cold exposure. Functional enrichment revealed strong repression of cell cycle, along with the induction of stress-responsive pathways, including small heat shock proteins, detoxification enzymes (CYPs, UDP-glucuronosyltransferase), immune effectors (antimicrobial peptides, lectins, PGRPs), and genes involved in cuticle remodeling. A subset of differentially expressed lncRNAs and TE-linked genes was associated with immune and chaperone responses, suggesting multilayered transcriptional regulation. These results indicate that RPW larvae respond to low temperature by downregulating non-essential, energy-intensive programs while activating molecular chaperones, detoxification and immune defenses, and reinforcing structural barriers. This pattern is consistent with an integrated strategy involving cold-induced metabolic depression and enhanced cryoprotection. Our results represent a fundamental step that will guide data-driven studies to determine whether the cold-response mechanisms identified here are fully deployed in RPW, as well as for future research on novel pest control strategies.