Comparative metabolomics provides insights into the metabolic reprogramming of the predatory Arma custos (Fabricius) during low-temperature storage.

Abstract

Introduction: Arma custos (Fabricius) is a promising generalist predator capable of controlling a wide range of insect pests; however, a temporal mismatch between mass-rearing supply and pest outbreaks limits its commercial application. Although cold storage is commonly used to extend shelf life, it imposes substantial physiological stress that may compromise insect quality.

Methods: To investigate the metabolic mechanisms underlying cold adaptation, we conducted comparative metabolomic analyses combined with enzyme activity assays on A. custos adults exposed to a gradual cooling protocol.

Results: Despite a decline in survival during cold storage, the insects underwent extensive metabolic reprogramming in response to thermal stress. In total, 1,434 metabolites were identified, among which lipids and lipid-like molecules accounted for the largest proportion (43.72%). A total of 1,275 differentially expressed metabolites (DEMs) were detected, indicating pronounced metabolic reorganization and overall downregulation during prolonged cold exposure. KEGG pathway enrichment analysis identified eight major metabolic pathways and 46 key DEMs, suggesting that lipid and carbohydrate metabolism are central to cold tolerance. Mechanistically, the accumulation of long-chain polyunsaturated phospholipids and sphingomyelin is hypothesized to represent a crucial strategy for maintaining membrane fluidity, whereas the downregulation of ceramide may contribute to the suppression of apoptosis. In addition, elevated trehalase activity and the accumulation of compatible solutes likely function as essential cryoprotectants and antioxidants.

Discussion: Collectively, these results provide a systematic characterization of the metabolic landscape of A. custos under low-temperature stress and offer a theoretical foundation for future functional studies and for optimizing cold storage strategies to enhance the performance of this biocontrol agent.