Entomopathogenic fungi have been widely studied for their potential as the effective biological control agents. Theyproduce variety of secondary metabolites with insecticidal activities, and it is reasonable to assume that entomopathogenicfungi might produce secondary metabolites modulating juvenile hormone for their survival against defense mechanismsof host insect. In this study, Acetone extracts of 189 entomopathogenic fungi cultured on unpolished rice medium werescreened for their juvenile hormone antagonist (JHAN) activities using the yeast-two hybrid system. Among them, 14extracts showed high level of JHAN activities and their insecticidal activities against Aedes albopictus were investigated.

The small brown planthopper (SBPH), Laodelphax striatellus, is one of the most serious pest insects of rice plants.Buprofezin has been used to control SBPH for more than a decade, however, the occurrence of buprofezin resistant SBPHwas reported recently. To develop an alternative pest control an alternative pest control strategy, RNA-seq of buprofezin-treatedSBPH was performed to screen the insecticidal target genes for RNA interference (RNAi). Six genes were selected fordsRNA synthesis, and applied to SBPH to assess the insecticidal efficacy. Two and three of those dsRNAs showed moderatedand substantial insecticidal activity up to 60% of mortality in one week, respectively. These results demonstrated the potentialof gene screening strategy for the development of RNAi-based pest management program.

Widespread use of chemical insecticides has resulted in development of insect resistance and natural products withbiological activities could become an attractive alternative to control insect pests. In order to find more effective insecticidesfor controlling mosquito, various mosquitocidal compounds are studied. Recently, juvenile hormone antagonists (JHANs)are known to be to safe and effective insecticides for control mosquito. In order to identify novel insecticidal compoundswith JHAN activity, several chalcones were surveyed on their JHAN activities and larvicidal activities against Aedes albopictuslarvae. Among them, 2’-hydroxychalcone and cardamonin showed high level of JHAN and mosquito larvicidal activities.These results suggested that chalcones with JHAN activity could be useful for control of mosquito larvae.

Actinobacteria have been known to produce variety of bioactive metabolites that include antibiotics and plant growthfactor. Also, Insecticidal compounds such as avermectin and tetranectin have been reported from actinobacteria. In thisstudy, to identify novel insect growth regulator (IGR)-based insecticidal compounds, 1,283 actinobacteria isolates weretested for their juvenile hormone antagonist (JHAN) activity using the yeast-two hybrid β-galactosidase assay. Amongthem, 25 isolates showed high level of JHAN activity and insecticidal activity against 3rd larvae of diamondback moth,Plutella xylostella. These results suggested that actinobacteria could be unparalleled source of novel IGR-based compounds.

Streptomyces species have been studied to find potent pest control agents as an alternatives to chemical insecticides.Previously, one of the ethyl acetate extract of Streptomyces isolates cultured on unpolished rice medium showed highlevel of juvenile hormone antagonist and larvicidal activities against pest insects including Aedes albopictus, Plutella xylostellaand Laodelphax striatellus. It has been known that the biosynthesis of secondary metabolites of Streptomyces could beinfluenced by a variety environments such as nutritional composition and growth conditions. In this study, to optimizeculture conditions for stable production of insecticidal compounds from this isolate, binding assay and bioassay-guidedmonitoring were conducted using various culture conditions.

Recently, it has been reported that plants produce variety of phytochemicals against insect pests as a part of their defencemechanism. In this study, to identify novel compounds that disrupt juvenile hormone (JH) receptor complex, plant essentialoil compounds were tested using in vitro yeast two-hybrid system transformed with the Aedes aegypti JH receptor complex.Among the plant essential oil compounds, farnesol interfered with pyriproxyfen-mediated binding of A. aegypti Met-FISC.In contrast, farnesyl acetate induced the binding of A. aegypti Met-FISC. Also, both compounds caused retardation ofovarian development and change of transcription level in female A. albopictus. These results could provide insights onthe plant-insect coevolution and may be useful for the development of insect specific and safe pesticides.

RNA interference (RNAi) has been considered as an alternative strategy to control agricultural pests whereby double-strandedRNA triggers a potent and specific inhibition of its homologous mRNA. Since small double-stranded RNAs are requiredfor various RNAi applications, there is a need for cost-effective methods for producing large quantities of high-qualitydsRNA. Bacillus thuringiensis produces much insecticidal proteins with expression of their encoding genes being drivenby sporulation-dependent promoters. To develop dsRNA mass-production platform utilizing Bt, the pHT1K-EGFP plasmidvector which has cyt1Aa sporulation-dependent promoter was constructed. The transcriptional level of target gene (EGFP)is higher 113 times than Bt reference gene (ssPE). It was applied to protect honeybee from Sacbrood virus, so targetgene was replaced to SBV-vp1. By ingestion of Bt-derived dsRNA to honeybee shows positive effect on SBV suppression.

Oyster mushrooms are one of the most famous mushrooms for foods in Korea. ‘Santari’ developed on this study is P. pulmonarius of oyster mushroom species. ‘Santari’ is a new variety of oyster mushroom for the bottle culture. It was bred by mating with monokaryons isolated from ‘GMPO20404’ and ‘Hosan’. The optimum temperature for the mycelial growth was 26～29°C on PDA medium and that for the primordia formation and the growth of fruiting body of ‘Santari’ was 22°C and 20°C on sawdust media. It took 34 days to finish spawn running, 3 days to finish primordia formation, 3 days to finish fruitbody growth in the bottle culture. In the characteristics of fruit body, pilei were round type and brownish, stipe color was white and stipe shape was long and thick. The yield per bottle was 172g/1,100ml and was 43% higher than that of control variety(Hosan). As results of the physical properties of fruit body, springness, cohesive, gumminess and brittleness of stipe tissue were 87%, 82%, 193g and 16kg, respectively. The values of them are lower than those of control except cohesive.

Oyster mushrooms are one of the most famous mushrooms for foods in Korea. ‘Santari’ developed on this study is P. pulmonarius of oyster mushroom species. ‘Santari’ is a new variety of oyster mushroom for the bottle culture. It was bred by mating with monokaryons isolated from ‘GMPO20404’ and ‘Hosan’. The optimum temperature for the mycelial growth was 26~29°C on PDA medium and that for the primordia formation and the growth of fruiting body of ‘Santari’ was 22°C and 20°C on sawdust media. It took 34 days to finish spawn running, 3 days to finish primordia formation, 3 days to finish fruitbody growth in the bottle culture. In the characteristics of fruit body, pilei were round type and brownish, stipe color was white and stipe shape was long and thick. The yield per bottle was 172g/1,100ml and was 43% higher than that of control variety (Hosan). As results of the physical properties of fruit body, springness, cohesive, gumminess and brittleness of stipe tissue were 87%, 82%, 193g and 16kg, respectively. The values of them are lower than those of control except cohesive.

에너지 음료는 카페인을 주성분으로 타우린, 비타민 같은 다른 energy-enhancing 성분을 함유하고 있다. 미국과 유럽에서는 글루쿠로노락톤이 에너지 음료에 첨가될수 있으나, 국내에서 의약품으로는 허가되어 있다. 따라서 식품 첨가물로는 그 사용이 금지 되어 있어, 지속적으로 수입 및 유통 음료에서 시험검사를 하여 규제하고 있다. 현재 분석법으로 사용하는 LC-PDA 법은 복잡한 유도체화 과 정을 거치고, 음료 중에 당류들이 위양성 결과를 나타내 기도 한다. 이런 기존 방법의 단점을 개선하기 위해 HILICESI- MS/MS (hydrophilic interaction liquid chromatography coupled to electrospray ionization tandem mass spectrometry) 를 이용한 분석법을 개발하고, 선택성, 직선성, 검출한계, 정량한계, 정밀도, 정확성, 재현성에 대하여 분석법 유효성 검증을 수행했고, AOAC, EURACHEM 가이드라인에 부합되는 결과를 얻었다.

The green peach aphid, Myzus persicae, is one of the most important pests of vegetable crops worldwide. This species cause direct damage by feeding on plant nutrients and indirect damage as transmits many virus vectors. The control of aphid has relied on the use of chemical insecticides and their intensive use over many years has led to the development of resistance. To surmount or avoid these problems, we screened the entomopathogenic fungi against green peach aphid and evaluated their virulences. Several entomopathogenic fungal isolates were selected with high virulence to green peach aphid. Additionally, the antimicrobial activity of the selected fungal isolates was tested and analyzed to phytopathogens. Consequently, these entomopathogenic fungi would be used effectively for dual control agents for the green peach aphid and phytopathogen.

Secondary metabolites isolated from Actinomycete have been studied to find potent pest control agents as their insecticidal and growth inhibitory activities. In order to investigate novel insecticidal compounds, second metabolites from 363 Actinomycete isolates were evaluated for their insect growth regulatory activities. Among them, ethyl acetate extracts from ten Streptomyces spp. showed high level of Juvenile hormone antagonist activity. In addition, their insecticidal activities were tested against larvae of Aedes albopictus, Plutella xylostella and Laodelphax striatellus. These results suggested that secondary metabolites from Streptomyces spp. could be used for development of novel IGR-based insecticides.