The effect of fumigation on the phosphine-susceptible and -resistant strains in the T. castaneum was evaluated using phosphine, ethyl formate, and combination with phosphine and ethyl formate (phosphine+ethyl formate). The Lethal Concentration Time (LCT)50 analysis of susceptible strains, late larva showed that phosphine (0.13 mg·h / L), ethyl formate (80.91 mg·h / L), and phosphine + ethyl formate (19.36 mg·h / L). The LCT50 of adult was 0.05 mg·h / L, 68.58 mg·h / L and 17.84 mg·h / L when treated with phosphine, ethyl formate, and phosphine + ethyl formate. The LCT50 of resistant strains, late larva was found to 33.32 mg·h / L of phosphine, 113.46 mg·h / L of ethyl formate and 129.85 mg·h / L of phosphine + ethyl formate, and the LCT50 of adult was 55.71 mg·h / L of phosphine, 85.39 mg·h / L, phosphine + ethyl formate 85.83 mg·h / L. The treatment of three fumigants (phosphine, ehtyl formate, and phosphine+ethyl formate) showed the possibility of controlling against T. castaneum of phosphine-susceptible and –resistant strains.

Spotted wing drosophila (SWD), Drosophila suzukii (Diptera: Drosophilidae), is an important quarantine insect pest on blueberry and strawberry exportation in Korea. Due to IPPC recommendations of replacement of methyl bromide (MB) and recent critical issue about its chronic inhalation toxicity to fumigator and related workers along with post-fumigation, alternatives to MB is urgently required. Thus, we evaluated efficacies of ethyl formate (EF) to SWD eggs using two different bioassay methods; using eggs oviposited on artificial diet and on blueberries naturally infested with SWD adults. In results, there was no differences between two bioassay methods in terms of LCT99 value of EF.

Methyl bromide (MB) has been still routinely used in quarantine fumigation on imported citrus, although there had been issuing chronic inhalation toxicity to fumigators and related workers as well as phytotoxic damages after fumigation. Ethyl formate (EF), is the only option to replace MB in terms of its safety for consumers (food additive and naturally occurred) and worker with higher threshold level limit (TLV = 100 ppm). Its application technology also provide cost effectiveness, good commercial practice in terms of application time (< 10 min) for 40 ft container. The replacement of MB with EF is recommended not to fumigate with hazardous and phasing-out MB on imported oranges.

To replace hazardous methyl bromide (MB) post-fumigation on imported fruits, due to insufficient ventilation process in industrial practice, alternative fumigation with liquid ethyl formate (EF) with N2 application, which is multi benefits to safe to workplace and environment, has been developed by APQA. Although EF was found to be shown proven efficacy to invasive external feeders such as mealybugs and scales on export and imported fruits and vegetables, there was still some conflicts to accept one of the phytosanitary disinfestation method somewhere because of on reliable and confirmative studies on between MB and EF in terms of efficacy to mealybugs on perishable commodities. In here, we evaluated comparative efficacy of EF and MB to target citrus mealybug, which was seems to be hard control pest, based on the current disinfestation guideline of them in Korea. The potential benefits of using liquid ethyl formate (EF) for future quarantine use could provide for safer workplace involved on and post-fumigation such as cold and packing storages, cost-effectiveness as well as meet the environmental friendly solution.

Stored grain pests can cause reduction of grain quantity, quality, commercial value and germination rate. Susceptibility of three fumigants, methyl bromide, ethyl formate and phosphine, were assessed on Tribolium castaneum, which is an important stored grain pest. On susceptible insects, LCT50 of phosphine was 0.654mg h/L for egg, 0.127mg h/L for late larvae, 0.105mg h/L for pupae and 0.048mg h/L for adult stage, respectively. LCT50 of methyl bromide was 33.193mg h/L for egg, 14.585mg h/L for late larvae, 8.616mg h/L for pupae and 11.967mg h/L for adult stage, respectively. LCT50 of ethyl formate were 25.165mg h/L for egg, 80.912mg h/L for late larvae, 176.326mg h/L for pupae and 68.578mg h/L for adult stage, respectively. On resistant insects, LCT50 of phosphine were 82.325mg h/L for egg, 33.315mg h/L for late larvae, 73.546mg h/L for pupae and 55.707mg h/L for adult stage, respectively. LCT50 of methyl bromide were 19.250mg h/L for egg, 43.413mg h/L for late larvae, 76.842mg h/L for pupae and 19.387mg h/L for adult stage, respectively. LCT50 of ethyl formate were 87.552mg h/L for egg, 113.457mg h/L for late larvae, 200.122mg h/L for pupae and 85.394mg h/L for adult stage, respectively.

The susceptibility of three fumigants, methyl bromide, ethyl formate and phosphine, and concurrent treatment of ethyl formate and phosphine were tested on Lasioderma serricorne. Susceptibility assessment were performed by treating 5 to 6 initial dosage on every growth stages of L. serricorne. The LCT50 of methyl bromide was 13.896mg h/L for egg, 36.038mg h/L for late larvae, 25.172mg h/L for pupae and 21.758mg h/ L for adult, respectively. The LCT50 of phosphine was 0.317mg h/L for egg, 0.649mg h/L for late larvae, 3.748mg h/L for pupae and 0.703mg h/L for adult, respectively. In case of ethyl formate, the LCT50 was 43.657mg h/L for egg, 137.606mg h/L for late larvae, 72.676mg h/L for pupae and 52.951mg h/L for adult, respectively. Concurrent treatment of ethyl formate and phosphine was performed by treating 5 to 6 initial dosage of ethyl formate with 0.5 mg/L phosphine for 4 hours on every growth stages of L. serricorne. The LCT50 of ethyl formate concurrent treatment was 13.746mg h/L for egg, 8.156mg h/L for late larvae, 27.087mg h/L for pupae and 11.353mg h/L for adult, respectively, and these results indicate that concurrent treatment can control pest with lower dosage and shorter period. Sorption rates and ventilation periods of each fumigants were also calculated for efficacy and safety

The existing ethyl formate fumigant is carbon dioxide (CO2) mixed liquified gas in metal cylinder, but this product type costs a lot to manufacture, translate and maintain cylinder. To supplement these problems, we have developed a new ethyl formate fumigation technique with nitrogen (N2) carrier. We assessed the susceptibility of mealy bugs, the most frequently detected pests in imported banana, and phytotoxicity of banana fruits. Ethyl formate and nitrogen were concurrently treated on citrus mealybug, one of the most resistant mealybug to fumigant, and ethyl formate was treated with LC50 product of independent treatment dosage. Nitrogen was treated with 7 dosages from 79% to 95% concentration. Phytotoxicity of banana was assessed by treating EF 35 mg/L with N2 79% for 14 days, and color, sugar contents and loss of weight were measured. EF with N2 treatment showed more than 50% of mortality on every growth stages, and there was no significant difference between control and treatment banana fruits. These results indicate that concurrent treatment of EF and N2 can be used to control mealybug in banana fruits.

Spotted wing drosophila, Drosophila suzukii, is an important pest of grape and strawberry because it lays egg inside fruit by damaging fruit surface. Recently, D. suzukii has been widely spreaded and causes several problems, so many countries include Australia designated D. suzukii as an important quarantine pest. Because of this, Korean farmers have trouble to export strawberry. In this study, we tested ethyl formate and phosphine to control D. suzukii, and also tested concurrent treatment of ethyl formate and phosphine to reduce phytotoxicity and enhance efficacy. When treated 35g/m3 of ethyl formate for 4 hours, mortality of egg, larvae, pupae and adult stages of D. suzukii was 22.2%, 21.1%, 19.2% and 28.3%, respectively. When treated 1g/m3 of phosphine for 24 hours, all stages of D. suzukii was completely controlled, but caused phytotoxic effect on strawberry. When treated with 35g/m3 of ethyl formate and 1g/m3 of phosphine concurrently for 4 hours, efficacy has been increased with less phytotoxicity than separate treatment. This result indicates that concurrent treatment enhanced efficacy with less phytotoxicity.

Ethyl formate (EF) fumigation under green house condition is a new concept. Its concentrations inside and surrounding of the glass house (GH) and vinyl house (VH) were evaluated for 4 h (during daytime) and 12 h (during nighttime) after fumigation along with the evaluation of post-fumigation EF concentrations. The cumulative EF concentration × time (Ct) value of the 6 sampling positions in VH were 22.67 and 17.53 g·h/m3, respectively for day and night fumigation, which were 2.62 and 4.53 g·h/m3 respectively for day and night application in GH. The EF level (PPM) outside the VH and GH as well as after 20-min post fumigation were < 50 ppm revealing its safety level as its’ threshold limit value (TLV) is 100 ppm. The new technology using liquid EF fomulation could be a key option in smart-farm technologies in future. (Supported by PJ0133562018, RDA)

It is uncommon to fumigate the live plants in quarantine. Ethyl formate (EF) fumigation was carried out in a 0.275 m3 chamber in laboratory for 12 h (over-night) to evaluate the mortality of 4 insect pests and to evaluate the phyto-toxic effect on their host plants. The tested doses were 1, 1.5 and 2 mg/L EF with or without nitrogen gas (N2). The phytotoxicity was evaluated 7 days post-fumigation based on the damage index (DI) scaling 0-4. Mortality >80% were recorded against thrips, whitefly and aphid in all the EF or EF + N2 treatments. Two-spotted spider mite was highly tolerant (<20% mortality at the highest dose tested) to EF. Except for perilla and sesame (DI = 4), EF was non-toxic to other vegetable crops at 1.5 mg/L EF. However, 1.5 mg/L EF+N2 increased DI by 3 for tomato, watermelon and green pumpkin. This new method fumigating live plants certainly demands lots of further experiments to ensure its practical application in farm level. (Supported by PJ0133562018, RDA)

수출입 묘목류에 있어서 깍지벌레류는 주요한 해충으로 다양한 묘목류에서 검출되고 있다. 깍지벌레류 중 우리나라의 소나무에 피해를 주고 있는 소나무굴깍지벌레는 연 2회 발생하는 해충으로 1세대는 4월, 2세대는 8월에 발생하여 소나무 잎에 피해를 준다. 따라서 본 연구에서는 수출입 묘목류에서 검출되는 깍지벌레류의 소독효과에 대한 정보를 제공하기 위하여 포스핀과 에틸포메이트 그리고 메틸브로마이드를 이용하여 소나무굴깍지벌레를 대상으로 훈증효과를 검정하였다. 포스핀을 소나무굴깍지벌레 알을 대상으로 0.06 mg/L 이상 처리시 난부화억제율은 100%였으며, 에틸포메이트 처리의 경우 성충은 2.6 mg/L, 알은 7.4 mg/L에서 100% 살충활성을 보였다. 그리고 메틸브로마이드를 40 g/㎥으로 2시간 훈증처리시 소나무굴깍지벌레 성충은 100% 치사하였으며, 알의 경우 26.0 mg/L을 처리했을 때 100%부화억제 효과를 보였다.

Azuki bean beetle (ABB), Callosobruchus chinensis (L.) is a cosmopolitan field-to-storage pest of legumes. Its female sex pheromone consists of two isomeric components, 2Z-homofarnesal and 2E-homofarnesal. Two day old virgin adults were exposed to sub-lethal fumigation doses (LC25=2.80 and LC50=3.32 mgL-1) of ethyl formate (EF) to see the effects on adult longevity, fecundity, sterility and female sex pheromone production. Longevity (female; P < 0.001, male; P < 0.001), fecundity (P < 0.001) and sterility (P < 0.001) were significantly affected. The Gas Chromatography-Mass Spectrometry for solid phase micro extraction revealed that release of both of the pheromone components were not affected by LC25 dose of EF. However, the fecundity (per female/day) was significantly (P < 0.001) stimulated by the tested EF doses when the female adults were treated irrespective of the male treatment, probably revealing a hormetic effect. This study provides insight into the effect of EF fumigation on biological activities of C. chinensis.