Trehalose accumulation contributes to enhanced cold stress tolerance in Telenomus remus, a dominant egg parasitoid of Spodoptera frugiperda.

Telenomus remus is a highly efficient biological control agent against Spodoptera frugiperda, owing to its capacity to successfully locate and parasitize inner layer eggs of egg masses. However, our previous studies have revealed its limited cold tolerance, a critical bottleneck in mass rearing of this wasp species. Understanding the cold tolerance mechanism of T. remus is crucial for improving rearing techniques, optimizing storage protocols, and enhancing the overall effectiveness of biological control strategies. Therefore, the overarching objectives of this study were to investigate the dynamic changes in mortality and cryoprotectant levels under different cold stress conditions, identify candidate genes and metabolites associated with cold tolerance, and elucidate the cold tolerance mechanisms in T. remus through physiological measurements, integrated transcriptomic and metabolomic analyses, and qRT-PCR validation. The results revealed that the survival rates of T. remus declined significantly with decreasing temperature. Interestingly, substantial accumulation of trehalose was observed under cold stress. Integrated multi-omics analysis indicated that the starch and sucrose metabolism pathway was crucial for mediating cold tolerance in T. remus. In this metabolic pathway, the expression levels of GAA (α-glucosidase) and GYS (glycogen synthase) exhibited a pronounced temperature-dependent upregulation. Collectively, these findings suggest that T. remus employs a cold-tolerance strategy centered on trehalose accumulation. This research advances our understanding of the molecular and biochemical foundations of cold adaptation in T. remus, and provides a theoretical basis for optimizing the storage strategies of T. remus biocontrol products.