Comparative Metabolic Profiling in Drosophila suzukii by Combined Treatment of Fumigant Phosphine and Low Temperature

Background/Objectives: The mechanisms of action of phosphine are diverse and include neurotoxicity, metabolic inhibition, and oxidative stress; however, its efficacy at low temperatures is unclear. Methods: Comparative metabolomics is suitable for investigating the response of the spotted-wing fly Drosophila suzukii to exposure toward a combination of cold stimuli and fumigant PH₃. Results: Under this combined exposure, 52 metabolites exhibiting significant differences in stress were identified and their physiological roles were analyzed in the Drosophila metabolic pathway. Most metabolites were involved in amino acids, TCA cycle, and nucleic acids. In addition, the alteration levels of cell membrane lipids, such as glycerophospholipids, sphingolipids, and glycerolipids, clearly showed changes in the combined treatment compared to PH₃ and low temperatures alone. Aconitic acid, a component of the TCA cycle, was completely inhibited by the combined treatment. Conclusions: These results suggest that treatment-specific indicators could be useful biomarkers to indicate the synergistic effects of PH₃ and low temperature on energy metabolism.