Integrated Approaches to Invasive Fruit Fly Disinfestation: Ethyl Formate Fumigation and Cold Treatment for Bactrocera scutellata as a Surrogate in Korea

The oriental fruit fly (<i>B. dorsalis</i>) poses a critical threat to domestic mandarin trade, necessitating effective phytosanitary measures. This study evaluated ethyl formate (EF) and phosphine (PH₃) fumigation as alternative disinfestation methods, either alone or in combination with cold treatment, using <i>B. scutellata</i>, pumpkin fruit fly, as a surrogate species. Eggs and third-instar larvae were tested under both naked and inoculated conditions. Results indicated that larvae were more susceptible to treatment than eggs. The LT_99% values for cold treatment (1.7 °C) were 8.6 and 12.4 days under naked and inoculated conditions, respectively. EF LCt_99% values were 265.7 and 1111.0 g h/m³. EF (LCt_50%) combined with PH₃ (1.0 g/m³) achieved up to 100% mortality, while EF (LCt_50%) followed by cold treatment (1.7 °C for 1-3 days) significantly enhanced mortality compared to cold treatment alone. This study offers foundational data to optimize EF-based quarantine treatments against <i>B. dorsalis</i>, supporting shorter treatment times and more cost-effective quarantine practices. Future studies should validate these findings under practical field conditions.