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.

Females of adzuki bean beetle (ABB), Callosobruchus chinensis (L.), a cosmopolitan field-to-storage pest of legumes, release sex pheromone consisting of two isomeric components, 2Z-homofarnesal and 2E-homofarnesal. Two day old virgin ABB adults were exposed to sub-lethal fumigation doses (LC25=0.0056 and LC50=0.0076 mgL-1) of phosphine (PH3) to evaluate the effects on adult longevity, fertility and 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 GC-MS for solid phase micro extraction exhibited the significant reduction of release of both of the pheromone components; 2Z-homofarnesal (P < 0.0038) and 2E-homofarnesal (P = 0.0009) when the females were exposed to LC25 dose of PH3. This study unveils the detrimental effects of PH3 fumigation on some of the biological parameters of ABB.

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)

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)

소나무재선충병의 예방을 위하여 실시하는 예방나무주사는 소나무재선충 피해를 예방할 수 있는 매우 효과적인 방제방법이지만 매개충에 대해서는 효과가 밝혀진 바 없다. 본 연구는 살선충제와 살충제가 혼합된 약제를 나무주사하여 소나무재선충병의 예방효과 뿐만 아니라 신초를 후식하는 하늘소류에 대해 소화중독에 의해 매개충살충까지 동시에 가능한 방제방법을 개발하기 위하여 실시하였다. Abamectin+Sulfoxaflor DC을 비롯한 3개 약종 2018년 3월 6일에 소나무에 나무주사 후 90여일 이 경과한 6월 5일에 소나무 가지에 망대를 설치하고 각 망대에 솔수염하늘소 1마리씩을 접종하여 7, 14, 21일의 살충율을 조사하였다. 나무주사된 3약종 모두 솔수염하늘소에 대하여 살충력이 우수한 것으로 나타났으며, 경기도 남양주시 잣나무림에 Abamectin+Sulfoxaflor DC를 나무주사 후 산란유인목을 설치하여 현장 실험을 실시한 결과 대조구와 비교하여 유충에 의해 발생된 목설흔이 매우 적게 나타나 소나무재선충병 방제에 적용 가능성을 확인할 수 있었다.

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.

The current protocols of methyl bromide (MeBr) fumigation on imported nursery plants, which are seriously infested with quarantine mealy bugs and scales, could be reevaluated because there were no limited uses of loading ratio, packing types etc. Another emerging issues is that the workplace health issues on MeBr fumigation are related with poor ventilation etc as well as well-known phytotoxic damages on them. In previous report, we have evaluated the efficacies of ethyl formate (EF) and phosphine (PH3) on different types of mealybugs. Herein, the phytotoxic damages of EF and PH3 on Alocasia, Sansevieria, Cactaceae and Croton genera were evaluated in terms of chlorophyll contents, color changes etc. This study showed that EF and PH3 fumigation on imported plants could be applicable to replacement of MeBr with further confirmation trials.

Methyl bromide (MeBr) is well-known as a hazardous chemical to exposed fumigators and related workers as well as a ozone depletion chemical. According to recent report in USA and Korea, when MeBr fumigated on orange and grape at low temperature (<10℃), absorbed MeBr on fruits was slowly released to workplace. To replace MeBr practices urgently, ethyl formate (EF) fumigation is considered safer to worker (TLV of EF = 100 ppm compared to MeBr's = 1 ppm) and free from residual problem. We reports confirmative liquid EF (FumateTM) with N2 trials, which is cost-effective and non-CO2 gas emitted, on imported grapes. The 4hr-fumigation of 70 gm-3of EF (CTP > 114 gh-3) in scale-up chamber (10m3) fumigation (20% l.r.), showed efficacies to many kinds of insect pests, non-phytotoxic damage, providing safer guideline at workplace.

The spotted wing drosophila (SWD), Drosophila suzukii, is classified exotic quarantine pest in Australia and EU, soSWD-free must be supported by evidence of surveys and phytosanitary measures in exported host agricultural commoditiesin Korea. From a quarantine control point of view, SWD is importantly considered as model insect pest for exotic fruitflies (Bactrocera dorsalis) in Korea as well because of similarity in ecological cycles. In evaluations of ethyl formate(EF) only and combined cold treatment to kill eggs and larvae of SWD, the combined EF fumigation applied at LCt50%(50% killed lethal concentration X time) and cold treatement (5℃) for > 5 days showed the promise to new conceptfor eradicating quarantine pest and these could be helpful to pre-develop exotic fruit fly management in Korea.

The spotted wing drosophila (SWD), Drosophila suzukii, is a severe pest of berry fruits like strawberry, blueberry, sweet cherry and grape in terms of quarantine. For the disinfestation of SWD, methyl bromide (MeBr) is the only option in quarantine practice. However, MeBr's current use will be phased out due to chronic inhalation toxicity to fumigators and related worker as well as ozone depletion properties. To replace MeBr, we evaluated the efficacy of ethyl formate (EF) and phosphine gas (PH3) to all different developmental stages of SWD at practical fumigation condition (>25 ℃). To achieve complete control of all stages of SWD, PH3 required > 6 hr exposure when applied at > 1.0 g m-3. In case of 4hr EF fumigation, the LCt99 (LCt99, 99% lethal concentration × time) of EF to egg, larvae and pupae of SWD was 198.09, 77.42 and 115.55 g·h m-3, respectively.

The bulb mite (BM), Rhizoglyphus echinopus, is hard to control in the harvested onion and garlic. Methyl bromide (MeBr) fumigation is the only option to eradicate BM at present. However, MeBr causes phytotoxic damage (index 3) to onion and garlic and highly toxic to fumigators. To replace MeBr, we evaluated ethyl formate (EF) and phosphine gas (PH3) to BM at 5℃ which is current practical fumigation temperature. The >140 g·h m-3 of EF for 24 h could completely control BM and this CT (concentration × time) product was slightly (index 1) phytotoxic to onion and garlic. Fumigation of 2 g PH3 required >120 h exposure to kill 100% of BM without any pyhtotoxic damage. Further researches are being planned to shorten the exposure time with synergistic effect between EF and PH3.