Evaluation of Ethyl Formate, Phosphine, and Their Combination to Disinfest Harvested Celery against Purple Scum Springtails

Abstract

<jats:p>Export celery (<jats:italic>Apium graveolens</jats:italic> var. <jats:italic>dulce</jats:italic>) from Australia has been affected by a natural infestation of purple scum springtails (<jats:italic>Hypogastrura vernalis</jats:italic>). These insects live inside the celery head, contaminating fresh celery, but do not cause any visible damage. As a result, purple scum springtail-infested celery has led to rejection for export with an impact on market value for fresh produce. In this study, fumigation with ethyl formate (EF), phosphine (PH<jats:sub>3</jats:sub>), and their combination on mortality of purple scum springtails in naturally infested celery was evaluated. Laboratory experiments were conducted using concentrations of 50, 60, and 90 mg·L<jats:sup>−1</jats:sup> of EF for 1, 2, and 4 hours; 1, 1.5, 2, and 2.5 mg·L<jats:sup>−1</jats:sup> of PH<jats:sub>3</jats:sub> for 2, 4, and 6 hours; and 20, 30, and 40 mg·L<jats:sup>−1</jats:sup> of EF combined with 1 mg·L<jats:sup>−1</jats:sup> of PH<jats:sub>3</jats:sub>, for 2 and 4 hours at the laboratory temperature 25 °C. Complete control was achieved at 90 mg·L<jats:sup>−1</jats:sup> of EF for 2 hours; however, phytotoxicity was observed in celery treated by EF at all concentrations. PH<jats:sub>3</jats:sub> at 2.5 mg·L<jats:sup>−1</jats:sup> achieved 100% mortality within 6 hours, and no phytotoxicity was evident. Mortality of 100% was achieved also at 30 and 40 mg·L<jats:sup>−1</jats:sup> EF combined with 1 mg·L<jats:sup>−1</jats:sup> of PH<jats:sub>3</jats:sub> for 2 and 4 hours exposure time; however, phytotoxicity occurred with EF alone treatments and with the combination. From these data, we conclude that PH<jats:sub>3</jats:sub> alone has potential as a fumigant for the preshipment treatment of celery infested with purple scum springtails.</jats:p>

Ethyl Formate Fumigation against Pineapple Mealybug, Dysmicoccus brevipes, a Quarantine Insect Pest of Pineapples

“…One of the limitations of EF is that it can negatively affect the quality of fresh commodities, including discoloration and accelerated decay of fruit [35,51,54]. However, EF phytotoxicity often depends on its concentration and the species and cultivar of treated plants [55,56] and can be minimized by optimizing treatment parameters, such as treatment concentration, time of exposure, and temperature [35,57,58]. Although EF treatment can cause phytotoxicity on pineapples at 100 g/m 3 EF for 4 h at 8 • C (personal observation, THK), in this study, there was no significant impact on sugar content, crown color, firmness, and weight loss when pineapples were treated with 70 g/m 3 EF for 4 h at 8 • C. This suggests a need for careful attention to treatment conditions, such as EF dosage, temperature, and duration of treatments.…”

Synergistic Effects and Toxic Mechanism of Phosphine with Ethyl Formate against Citrus Mealybug (Planococcus citri)

“…MB can be completely replaced only when a clear combination treatment efficacy and mechanism of action are evaluated. The efficacy of combination treatment of PH 3 with EF has been evaluated in several studies [1,7,35], but there is a lack of understanding of the mechanisms. PH 3 is used as the most global alternative fumigant to MB, but there are still some issues to be solved: a relatively long treatment time with slow activity and high resistance [8].…”