Project description:<p>Telenomus remus, an egg parasitoid capable of penetrating multi-layered egg masses, has emerged as a promising candidate for the biological control of Spodoptera frugiperda. Nevertheless, our prior investigations have uncovered that its limited cold tolerance represents a critical bottleneck in mass rearing. To overcome this challenge, the overarching objectives were to identify candidate genes and metabolites associated with cold tolerance, investigate the dynamic changes of cryoprotectants under different stress conditions, and elucidate the cold tolerance mechanisms of T. remus. The results revealed that the survival rates of T. remus declined progressively as temperature decreased. Notably, a significant accumulation of trehalose was observed as the stress temperature decreased. Integrated multi-omics analysis indicated that the starch and sucrose metabolism pathway played a key role in mediating cold tolerance in T. remus. Within this metabolic pathway, the expression levels of GAA (α-glucosidase) and GYS (glycogen synthase) exhibited a clear temperature-dependent upregulation trend. Collectively, these findings suggest that T. remus adopted a cold-tolerance strategy centered around trehalose accumulation. These research advances our understanding of the molecular and biochemical foundations of cold adaptation in T. remus, while also highlighting trehalose-mediated osmotic regulation as a prioritized research direction for future ectotherm thermotolerance studies.</p>