Cold-Chain Compatible Ethyl Formate Fumigation for Phytosanitary Disinfestation of Drosophila suzukii in Blueberries

Ethyl formate (EF) is a promising alternative to methyl bromide for postharvest disinfestation, but berry export chains require efficacy under refrigerated handling without loss of marketable quality. Using spotted-wing drosophila (Drosophila suzukii) in blueberries as a cold-chain model, we compared stage-specific tolerance at 5 to 15 °C and identified 1-day-old eggs as the most tolerant stage, with mortality strongly temperature dependent. Egg-stage concentration to mortality relationships were quantified under 4 h exposures at 5, 10, and 15 °C to nominate temperature-specific intensities within EF flammability safety limits. Candidate schedules (69, 83, and 94 mg·L^-1 for 4 h at 5, 10, and 15 °C) were confirmed by verification-scale zero-survivor tests under simulated cold-chain conditions, achieving complete control of the most tolerant egg stage. Post-treatment quality was assessed after 1, 7, and 14 days of cold storage. Weight loss, firmness, total soluble solids, titratable acidity, sucrose, and proanthocyanidins were driven mainly by storage time and temperature. EF effects were limited to transiently elevated respiration early in storage, with no detectable injury, decay, or adverse changes in appearance or other physicochemical attributes. Overall, EF provides a cold-chain compatible processing window integrating efficacy, operational safety, and quality preservation for refrigerated blueberry export logistics.