Efficacy and Phytotoxicity Assessment of Successive Application of Methyl Bromide and Cold Treatment on Export Strawberry Fruits

SIMPLE SUMMARY: Spotted wing Drosophila, Drosophila suzukii, is an important quarantine pest in Korea due to its oviposition behavior. In this study, insecticidal effects of methyl bromide (MB) alone and successive application of methyl bromide and cold treatment were compared to examine their potential to reduce methyl bromide usage and shorten the cold treatment periods. Eggs, larvae, and pupae were subjected to treatment with fumigants to determine the 50 and 99% lethal concentration time values. The results show that, through treatment with methyl bromide plus cold, control can be achieved at lower concentrations than for treatment with methyl bromide alone and with shorter treatment periods than for treatment with cold treatment alone. Phytotoxic effects from successive treatment on strawberry were not observed. Therefore, methyl bromide plus cold treatment can effectively control D. suzukii in strawberry without damage to fresh fruits. ABSTRACT: Recently, spotted wing Drosophila, Drosophila suzukii, is globally prevalent and causes agricultural losses to many fruits. To export Korean strawberry, methyl bromide fumigation is required to remove D. suzukii infestations, but Korean strawberry farmers are worried about fruit damage because methyl bromide can cause phytotoxicity on fresh commodities. In this report, we assessed the efficacy and phytotoxicity of single and successive application of methyl bromide and cold treatment on an export variety of strawberry to reduce fruit damage. The currently recommended dosage of methyl bromide, 40 g/m(3) for 3 h at 18 °C, was enough to control all stages of D. suzukii without phytotoxicity. A dosage of 20 g/m(3) of methyl bromide treatment for 3 h, followed by 1 d of cold (0 °C) treatment, showed 100% mortality in all growth stages of D. suzukii without fruit damage. Successive application of methyl bromide and cold treatment shows potential as a method of decreasing phytotoxicity and reducing the use of methyl bromide for environmental considerations.