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 (B. dorsalis) 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 B. scutellata, 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 LT99% values for cold treatment (1.7 °C) were 8.6 and 12.4 days under naked and inoculated conditions, respectively. EF LCt99% values were 265.7 and 1111.0 g h/m3. EF (LCt50%) combined with PH3 (1.0 g/m3) achieved up to 100% mortality, while EF (LCt50%) 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 B. dorsalis, supporting shorter treatment times and more cost-effective quarantine practices. Future studies should validate these findings under practical field conditions.