Oriental Fruit Fly: Factors Affecting Ethylene Dibromide Fumigation of Infested Papayas12

Abstract

The minimal dose of ethylene dibromide (EOB) needed to obtain 99.997% mortality of eggs and larvae of Dacus dorsalis Hendel in papayas, Carica papaya L., varied with the concentration of EDB in the fumigation chamber, the type and number of containers, and the fumigation temperature. The effect of container type on the EDB concentration after 0.5 h of fumigation was increased adsorption of EDB in the following order: perforated polyethylene tray < painted wooden field box < wooden field box ≤ fiberboard carton. Hot water treatments to control anthracnose of papaya improved the efficacy of EDB fumigation and reduced EDB residues more as a postfumigation treatment than prefumigation treatment. The quarantine treatment developed for oriental fruit fly-infested papayas in perforated polyethylene trays was fumigation with 7 g EDB/m3 for 2 h at 21.1°C and loading of 46% (by volume). The EDB residues in such fumigated papayas after 1-, 3-, and 5-day storage in cartons at 12.8°C were 2.1±0.12, 0.6±0.05, and 0.4±0.07 ppm, respectively. When similarly treated fruits were hot water-treated for 20 min at 46.1°C after the fumigation, the residues, at similar times and storage, were 1.8±0.2, 0.5±0.05, and 0.1 ±0.02 ppm. The quarantine treatment developed for fruits in wooden field boxes was fumigation with 8 g EDB/m3 for 2 h at 21.1°C plus postfumigation hot water treatment at 60.6°c for 20 sec. For such fruits stored 1 and 3 days in cartons at 20.0°-25.6°C (ambient temperature), the EDB residues were 0.4±0.04 and 0.05 ppm to trace, respectively; after 1, 3, and 5 days of storage at 7.2°C, the residues were 2.1±0.13, 0.7±0.06, and 0.3±0.02 ppm, respectively.