Fruit Quality Improvement by Applying Salt Stress and Root Zone Limitation in Hydroponically Grown Tomatoes

Sihyeon Jeong,Michiko Takagaki,Changhoo Chun 한국원예학회 2012 한국원예학회 학술발표요지 Vol.2012 No.10

Establishment of Entomopathogenic Fungal Virulence Assay System Against Riptortus clavatus (Heteroptera: Alydidae)

Sihyeon Kim,Se Jin Lee,Jeong Seon Yu,Sung Duk Seo,Han Wool Cho,Yu-Shin Nai,Jae Su Kim 한국응용곤충학회 2014 한국응용곤충학회 학술대회논문집 Vol.2014 No.04

Bean bug, Riptortus clavatus Thunberg (Heteroptera: Alydidae) causes serious damage to Leguminosae. Herein an entomopathogenic fungal virulence assay system against bean bugs was established to construct a fungal database which can be used in integrated pest management (IPM). First to obtain as many bean bugs as possible at the same stage, host plant-preference and developmental synchronization of bean bugs were investigated. In the preference assay, five pairs of adults were infested in a plastic cage, where a pot of green bean, pea or cowpea was previously placed. The highest fecundity and the fastest development of bean bug was observed in the green bean cage. Secondly, in the synchronization experiment, eggs were collected from the cage of adults in 1, 3, 5 and 7 days after oviposition and transferred to a fresh cage with green beans. From the every 4 days of survey, similar stages of bean bugs were found in the cages with the oviposition for 1 and 3 days, rather than the longer times of oviposition. A fungal bioassay against bean bugs was conducted using the bean bugs from the above insect rearing system. Ten Beauveria bassiana isolates were cultured on quarter-strength Sabouraud dextrose agar (¼SDA) for 7 days at 25°C. Ten 4th instar of nymphs were placed on a cultured plate for 1 hour and tranferred to a fresh moisturized plate with grains of green bean. ERL836 isolate treatment showed the highest virulence and fungal mycosis was observed on the bean bugs. In conclusion, these results can be useful to establish an entomopathogenic fungal database for IPM.

Control of Entomopathogenic Fungal Disease in Mealworm Rearing System

Sihyeon Kim,Se Jin Lee,Jeong Seon Yu,Yu-Shin Nai,Jae Su Kim 한국응용곤충학회 2014 한국응용곤충학회 학술대회논문집 Vol.2014 No.10

Mealworm, Tenebrio molitor L. (Coleoptera: Tenebrionidae) has high and safe protein contents, which enables it to be animal feed. However, occurrence of entomopathogenic fungi in mealworms is one of the limitations for mass production. In this work, we investigated relationships between abiotic conditions and occurrence of fungal pathogens and established an effective control method using fungicides. In virulence assay, third instar mealworm larvae were sprayed by six entomopathogenic Beauveria bassiana isolates and kept under high relative humidity; B. bassiana ERL1575 isolate had highest virulence. Under normal humidity, ERL1575 conidia showed different virulence between spray (~0% virulence) and digestion (~80% virulence) method. Furthermore, mealworms, which digested conidia, were exposed to various temperature (20-35°C) and humidity (1-3 ml distilled water spray/35 mm diam. dish) conditions for 5 days. All the treatments showed ~90% virulence except 35°C incubations (~20% virulence), but irrespective to the humidity conditions. Forty chemical fungicides were assayed against conidial germination and hyphal growth of ERL1575. Fluazinam and mancozeb showed strong inhibition of conidial germination at standard application dose (SD), 1/2 SD and 1/5 SD; besides, fluazinam showed strong inhibition of hyphal growth. When fluazinam and mancozeb were applied to the fungal conidia-inoculated wheat bran, most of mealworms were alive after 3 days post application. However, high mortality rate (~100%) were observed in the conidia-inoculated wheat bran without any fungicides. In conclusion, this work suggests that B. bassiana isolates could be pathogens at <30°C when they were digested by mealworms, and fluazinam and mancozeb would be used as effective control agents against the pathogen.

Production of thermotolerant insect-killing Beauveria bassiana and Metarhizium anisopliae granules in Italian millets

Jeong Seon Yu,Se Jin Lee,Sihyeon Kim,Min Ho Song,Jae Su Kim 한국응용곤충학회 2015 한국응용곤충학회 학술대회논문집 Vol.2015 No.04

Entomopathogenic Beauveria bassiana and Metarhizium anisopliae are well-known biological control agents worldwide and have high potential in industrialization. However their thermo-susceptibility limits long-term storage under high temperature conditions and high insecticidal activity after application to target pests. Herein we isolated highly virulent isolates, B. bassiana JEF006 and JEF007 and M. anisopliae JEF003 and JEF004, and produced in three grains, such as sorghum, millet and Italian millet as substrates for solid cultures, followed by thermotolerance assays to compare the potential of the three substrates for thermotolerance. The JEF isolates were exposed to dry and wet heat at 50°C and overall conidia were more stable under dry heat condition rather than wet heat. Of the three grains, Italian millet was superior to the other grains in the production of thermotolerant conidia. Additionally Italian millet did not severely aggregated, which enabled air to penetrate into the substrate well compared to the sorghum and millet. JEF isolates were more thermotolerant when they were kept in oil conditions as carriers of an oil-based formulation. This work suggests that Italian millet can be used as an effective substrate to produce more thermotolerant conidia, thus maintaining viability for long times under unfavorable environment and biological activity against target pests.

Relationship between substrate and conidial heat resistance in entomopathogenic Beauveria and Metarhizium

Jeong Seon Yu,Se Jin Lee,Sihyeon Kim,Min Ho Lee,Jae Su Kim 한국응용곤충학회 2015 한국응용곤충학회 학술대회논문집 Vol.2015 No.10

Hypocreales entomopathogenic Beauveria bassiana and Metarhizium anisopliae are well-known biological control agents worldwide and have high potential in industrialization. However their thermo-susceptibility limits long-term storage under high temperature conditions and high insecticidal activity after application to target pests. Herein we isolated highly virulent isolates, B. bassiana JEF006 and JEF007 and M. anisopliae JEF003 and 004, and produced in three grains, as substrates for solid cultures, followed by thermotolerance assays to compare the potential of the three substrates. The JEF isolates were exposed to dry and wet heat at 50°C and overall conidia were more stable under dry heat condition rather than wet heat. Of the three grains, Italian millet was superior to the other grains in the production of thermotolerant conidia. Additionally Italian millet did not severely aggregated, which enabled air to penetrate into the substrate well compared to the sorghum and millet. JEF isolates were more thermotolerant when they were kept in oil conditions. The conidia of JEF 007 and 003 wild type and AtMT-based generating random mutants were subjected to SDS-PAGE. A significant relationship between conidial thermotoelrance and detected proteins was observed. This work suggests that Italian millet can be used as an effective substrate to produce more thermotolerant conidia, thus maintaining viability for long times under unfavorable environment and biological activity against target pests.

Optimization of entomopathogenic fungal production to induce high mortality against Riptortus pedestris

Min Ho Song,Jeong Seon Yu,Sihyeon Kim,Se Jin Lee,Jae Su Kim 한국응용곤충학회 2015 한국응용곤충학회 학술대회논문집 Vol.2015 No.10

Bean bug, Riptortus pedestris is an agriculturally serious pest in north eastern Asian countries, damaging to several legumes and fruit trees. Chemical pesticides have been largely used to control the pest but it encounters insecticide-resistance and environmental toxicity issues. Alternatively different mode of action and environmentally sound pest management system can be found in entomopathogenic fungal insecticides. Herein we developed a platform to optimize the fungal production to express their maximum virulence against bean bug, by focusing on solid culture system for thermotolerance, formulation to select effective surfactants to carry the fungal conidia on the cuticles, and relationship between environmental abiotic factors and fungal mortality. First to produce highly thermotolerance fungal conidia, Beauveria bassiana and Metarhizium anisopliae isolates were cultured on several granular cereal substrates, which could be subjected to formulation process. Among the tested media, four media (millet, non-glutinous italian foxtail millet, glutinous italian foxtail millet, brown rice) were superior to the other grains in the spore production and thermotolerance. Next to efficiently deliver the fungal conidia on the cuticles of bean bug, total of six surfactant (CO-2.5, CO-12, LE-7, PE-61, TED-3 and Siloxane) was used to experiment. CO-12 was superior to the other surfactant in mortality of 100 ppm consistence. This work suggests that solid culture system and formulation and application should be seriously considered to reach an optimal level of mortality by inducing their maximum virulence.

Construction of entomopathogenic fungal library based on Tenebrio molitor larval assay system

Jong Cheol Kim,Sihyeon Kim,Min Ho Song,Jeong Seon Yu,Mi Rong Lee,Se Jin Lee,Jae Su Kim 한국응용곤충학회 2015 한국응용곤충학회 학술대회논문집 Vol.2015 No.10

Entomopathogenic fungi are facultative microorganisms, dwelling in soil or infecting host insects, and some of the genera have been used as biological control agents worldwide. Collection of fungal isolates should be a platform for the development of highly effective resources, thus in this work we constructed a fungal library using a mealworm pathogenecity-based fungal collection method and further characterized some isolates with high virulence. A phylogenetic three was generated, and of the isolates 17 isolates’ biological features were characterized, such as morphology, spectrum of virulence, cultural characteristics, thermo-stability of fungi, production of biologically active materials, such as enzymes. This work reports an attractive entomopathogenic fungal library including the information of effective isolates in pest management.

PBDEs and methoxylated-BDEs in antarctic toothfish (Dissostichus mawsoni)

Sihyeon Bak,Minkyu Choi,Jeong-Bae Kim,In-Seok Lee 한국분석과학회 2017 학술대회논문집 Vol.2017 No.11

전국 주요 양식장 퇴적물과 양식생물 내 PBDEs와 대사체 분포

박시현 ( Sihyeon Bak ),이인석 ( In-seok Lee ),최민규 ( Minkyu Choi ),김정배 ( Jeong-bae Kim ) 한국환경분석학회 2017 환경분석과 독성보건 Vol.20 No.3

In this work, the concentrations of several polybrominated diphenyl ethers (PBDEs) and methoxylated BDEs (MeO-BDEs) in the sediment and organisms collected from aquaculture farms along the Korean coasts were evaluated in order to study their occurrence and distribution. The concentrations of the PBDE and MeO-BDE congeners were measured by using a high-resolution gas chromatograph coupled to a mass spectrometer based on selected ion monitoring. It was found that the concentrations of the PBDEs and MeO-BDEs in the sediment and organisms from the southern coasts were higher than those found in samples from the western and eastern coasts (p<0.05). Similar results were obtained for the persistent organic pollutants (POPs) such as polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs), and dioxin-like polychlorinated biphenyls (DL-PCBs), indicating a similar contamination source or environmental behavior of these compounds. Relatively higher concentrations of PBDEs and MeO-BDEs were found in bivalves and urochordates as compared to those determined in seaweed, which could be related to their lipid contents. Deca-BDE and tetra-MeO-BDE were the predominant homologues of PBDE and MeO-BDE groups present in both the sediment and the organisms, respectively. Meanwhile, the concentration of MeO-BDEs appeared to be higher than that of PBDEs, which might be attributed to both the natural formation of MeO-BDEs in the marine ecosystem and the transformation of PBDEs to MeO-BDEs.

Growth and Total Polyphenolic Compounds Contents of Vegetable Sprouts as Affected by Light Quality and Intensity of Light-Emitting Diodes

Hyunseung Hwang,Sihyeon Jeong,Suyeon Lee,Changhoo Chun 한국원예학회 2014 한국원예학회 학술발표요지 Vol.2014 No.5