A Thermo-Sensitive Molecular Switch: Pyrexia-1 Dynamically Regulates Low-Temperature Adaptation in Chrysoperla nipponensis

Cold tolerance of natural enemy insects is a critical determinant of their overwintering survival and efficacy in biological control. The green lacewing (<i>Chrysoperla nipponensis</i>) is an important natural enemy insect that overwinters as adults in nature; however, its high overwintering mortality severely limits its effective application in spring. To investigate the molecular mechanisms underlying low-temperature adaptation, this study focuses on the temperature-sensitive Transient Receptor Potential (TRP) channels and their roles in the cold tolerance of <i>C. nipponensis</i>. The TRPA subfamily gene, <i>Pyrexia-1</i>, was identified and found to be significantly downregulated upon cold exposure. A functional analysis indicates RNAi-mediated knockdown of <i>Pyrexia-1</i> significantly lowered both the supercooling point and the freezing point of <i>C. nipponensis</i> adults, enhancing their survival rate at -10 °C. These results indicate <i>Pyrexia-1</i> as a negative regulator of cold tolerance. Further mechanistic investigation revealed that inhibition of <i>Pyrexia-1</i> function specifically down regulates the expression of trehalase (<i>TRE1</i>) genes, resulting in a marked accumulation of the cryoprotectant trehalose in adults. This metabolic adjustment was accompanied by the upregulation of heat shock protein Hsp70. Overall, these findings establish <i>Pyrexia-1</i> as a critical molecular switch linking temperature-sensing signals to the metabolic pathways governing freeze resistance, thereby orchestrating the systemic cold adaptation in <i>C. nipponensis</i>. This discovery provides novel insights into the molecular basis of insect low-temperature adaptation and suggests a potential strategy for enhancing the overwintering capacity of natural enemy insects by targeting this regulatory node.