Assessing the quarantine potential of ethyl formate as a stand-alone phytosanitary treatment against Ceratitis capitata: A comparative study on naked condition and natural infestation in mandarin

Abstract

The Mediterranean fruit fly, Ceratitis capitata (Wiedemann) (Diptera: Tephritidae), is a globally invasive pest that threatens biosecurity and agricultural trade due to its broad host range and high adaptability. Effective quarantine treatments are essential to prevent its introduction and establishment. This study evaluated the efficacy of ethyl formate (EF) fumigation as a phytosanitary treatment against C. capitata under two conditions: (1) naked condition and (2) natural infestation in mandarin. EF fumigation was conducted at 23 °C for 4 h, and mortality was obtained across different developmental stages. Under naked conditions, LCt_99% values varied across developmental stages, with pupae showing the highest resistance (631.33 g h/m³) and adults the highest susceptibility (89.87 g h/m³) and eggs, 1st-2nd instar larvae and 3rd instar larvae were 406.86, 296.69 and 261.76 g h/m³, respectively. In naturally infested mandarins, significantly higher EF concentrations were required to achieve similar mortality levels, with LCt_99% values for eggs and 1st-2nd instar larvae recorded at 745.18 g h/m³ and 642.42 g h/m³, respectively. These findings suggest that EF fumigation is more effective in direct exposure conditions, whereas the penetration limitations in citrus fruits necessitate higher dosages. This study provides critical data for establishing effective EF based quarantine treatments against C. capitata, contributing to the development of standardized phytosanitary treatment protocols.