Evaluating the feasibility of ethyl formate fumigation as a stand-alone phytosanitary treatment of Bactrocera dorsalis in mandarin fruit

Authors: KWON, TAE HYUNG - Orise Fellow; KIM, DONG-BIN - Kyungpook National University; KIM, KYEONGNAM - Orise Fellow; ROH, GWANG-HYUN - Gyeongsang National University; KIM, BONG-SU - Animal And Plant Quarantine Agency; LEE, SUNG-EUN - Kyungpook National University; LEE, BYUNG-HO - Gyeongsang National University; Cha, Dong

Submitted to: Journal of Asia-Pacific Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/24/2025
Publication Date: 8/30/2025
Citation: Kwon, T., Kim, D., Kim, K., Roh, G., Kim, B., Lee, S., Lee, B., Cha, D.H. 2025. Evaluating the feasibility of ethyl formate fumigation as a stand-alone phytosanitary treatment of Bactrocera dorsalis in mandarin fruit. Journal of Asia-Pacific Entomology. 28(3). https://doi.org/10.1016/j.aspen.2025.102466.
DOI: https://doi.org/10.1016/j.aspen.2025.102466

Interpretive Summary: Oriental fruit fly (OFF) is a major pest and key trade barrier of tropical fruit, such as citrus. During an OFF outbreak, all fruits and potential host materials within the quarantine area are destroyed to prevent further spread, causing serious economic losses to citrus and other fruit growers. Currently, there is no emergency treatment commercially feasible to move impacted fruit out from an OFF quarantine area. In this study, stand-alone 4 hr ethyl formate fumigation treatment was evaluated for its feasibility as a phytosanitary treatment during an emergency situation. Although stand-alone EF treatment was effective at controlling OFF infested in citrus fruit, the high EF dose required to control OFF inside fruit caused significant damage on fruit quality, indicating the need of alternative approaches. We discuss future research directions aimed at maintaining treatment efficacy while minimizing fruit damage by combining different phytosanitary treatment options.

Technical Abstract: Oriental fruit fly, Bactrocera dorsalis, is one of the most destructive quarantine pests of fruits and vegetables, with increasing incursions reported worldwide. During a B. dorsalis outbreak, all fruits and potential host materials within the quarantine area are destroyed to prevent further spread. As a first step toward developing an emergency treatment to allow fruit movement from a B. dorsalis quarantine area, we evaluated the feasibility of using ethyl formate (EF) fumigation as a stand-alone phytosanitary treatment against B. dorsalis. In EF efficacy trials with B. dorsalis eggs and larvae in the absence of fruit (naked conditions), eggs were the most tolerant life stage, with LCt99 values—lethal concentration x time products that cause 99% mortality—of 716.9 and 1,271.0 g h/m³ at 20 and 4°C, respectively, followed by first and third larvae. When B. dorsalis were artificially inoculated into mandarin fruit, significantly greater EF doses were necessary to control B. dorsalis inside fruit, with the LCt99 values for eggs increased to 1,606.0 and 1,761.0 at 20 and 4°C, respectively. Although these calculated EF doses were effective against B. dorsalis, they caused significant damage on quality of mandarins, including reduced sugar content and increased fruit decay. These findings indicate that EF fumigation alone is not a feasible stand-alone treatment for disinfesting B. dorsalis in mandarins. We discuss future research directions aimed at maintaining treatment efficacy while minimizing fruit damage by combining EF fumigation with other phytosanitary treatments.