본 연구에서는 주요 발생지인 구례 지역의 산수유, 때죽나무를 중심으로 2018년 8월에서 9월 사이에 갈색날개매미충 월동 난괴를 채집하여 날개매미충알벌(phanuromyia spp.)의 온도별(15℃, 20℃, 25℃, 30℃) 발육기간, 수명 및 우화 후 15일간의 총 산란수를 조사하였다. 날개매미충알벌의 발육기간은 25℃에서 알 2.6일, 유충 5.4일, 번데기 15.0일, 30℃에서 알 1.9일, 유충 7.6일, 번데기 13.7일이 소요되었다. 날개매미충알벌 성충의 온도별 수명은 15℃에서 암컷 77.4일, 수컷 66.6일, 20℃에서 암컷 49.0일, 수컷 44.0일, 25℃에서 암컷 27.6일 수컷 28.4일, 30℃에서 암컷 18.0일, 수컷 14.0일로 암수 모두 사육온도가 높아질수록 수명이 짧아졌으며 15℃와 30℃에서만 암수 수명의 차이가 있었다. 또한 온도별 총 산란 수는 15℃를 제외한 나머지 세 가지 사육온도에서 산란 수 차이는 없었으나 25℃에서 평균 23.2개로 가장 높았다.

RNA interference (RNAi) has been considered as an alternative strategy to control agricultural pest whereby double-stranded RNA triggers a potent and specific inhibition of its homologous mRNA. Since small dsRNAs are required for various RNAi applications, there is a need for cost-effective methods for producing large quantities of high-quality dsRNA. In this study, Bacillus thuringiensis (Bt) based dsRNA production platform was established under control of sporulation-dependent promoter and vp1 gene of Sacbrood virus (SBV) was introduced. The dsRNA against vp1 gene produced from the Bt suppressed the replication of SBV. In addition, the dsRNA was assembled into inulin coated-nanoparticle to increase stability of dsRNA in environment.

Streptomyces has been reported to produce various secondary metabolites which have the potential to become environmentally safe insecticides. In this study, 1,274 streptomyces culture filtrates were screened for their JHAN activity in order to identify novel insecticidal compounds. 34 isolates with high levels of JHAN activity were selected, and their insecticidal activities were tested against Plutella xylostella larvae. Among them, IMBL-263 which was revealed to be Streptomyces anulatus by 16s rRNA sequencing showed the highest insecticidal activity. Also, systemic activities of secondary metabolites extracted from the S. anulatus on plant, Brassica napus, were investigated. These results suggested that secondary metabolites from the S. anulatus might be useful for development of novel environmentally benign insecticides.

The development of entomopathogenic fungi has received increasing interest as part of integrated pest management strategies as biocontrol agents. It is reasonable to assume that entomopathogenic fungi might produce secondary metabolites modulating juvenile hormone for their survival against defense mechanisms of host insects. In this study, acetone extracts of 189 entomopathogenic fungi cultured on unpolished rice medium were screened for their juvenile hormone antagonist (JHAN) activities using the yeast-two hybrid system. Among 14 extracts showing JHAN activities, extract of the F-145 showed high level of insecticidal activities against both Plutella xylostella and Aedes albopictus. This isolate was identified as Lecanicillium attenuatum. These results suggested that the Lecanicillium attenuatum could be useful for development of eco-friendly insecticides.

Beet armyworm, Spodoptera exigua, is known to be hard-to-kill pest by having high resistance to insecticides and its control is intensely dependent on fewer insecticides. In this study, the ethyl acetate extract of Streptomyces sp. was evaluated to find novel insecticidal agents against S. exigua. In order to determine the identity of insecticidal compounds, the crude ethyl acetate extract was fractionated based on the TLC profiling and bioassay-guided monitoring. These results indicated that the non-polar fraction have high level of insecticidal activity against second instars of S. exigua. These findings suggested that secondary metabolites produced by Streptomyces sp. could be considerable potential resources as novel insecticidal formulation candidates.

Insect growth regulators (IGRs) are insecticides that disrupt the normal development of target insects. Among the IGR insecticides, juvenile hormone (JH)-related IGRs are of particular interest because they stimulate or interfere with the formation of JH receptor complex. In the precious studies, novel JH-related IGRs with JH agonist (JHA) and antagonist (JHAN) activity were identified by using yeast two-hybrid system transformed with the Aedes aegypti JH receptor complex. In this study, the transcriptomic responses of Aedes albopictus were investigated upon JHA and JHAN, respectively. These results will provide important information about understanding of impact of JH-related IGRs in transcription level.

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.

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.

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.

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.

This study investigated the effect of Charcoal:Dextran Stripped fetal bovine serum (CDS FBS) and heat-inactivated FBS (HI FBS) in embryo culture medium on their ability to support in vitro development of bovine embryos. The developmental ability and quality of bovine embryos were determined by assessing their cell number, lipid content, mitochondrial activity, gene expression, and cryo-tolerance. The percentages of embryos that underwent cleavage and formed a blastocyst were significantly (P<0.05) higher in medium containing CDS FBS than in medium containing HI FBS (42.84 ± 0.78% vs. 36.85 ± 0.89%, respectively). Furthermore, the beneficial effects of CDS FBS on embryos were associated with a significantly reduced intracellular lipid content, as identified by Nile red staining, which increased their cryo-tolerance. The post-thaw survival rate of blastocysts was significantly (P<0.05) higher in the CDS FBS than in the HI FBS group (85.33 ± 4.84% vs. 68.67 ± 1.20%). Quantitative real-time PCR showed that the mRNA levels of acyl-CoA synthetase long-chain family member 3, acyl-coenzyme A dehydrogenase long-chain, hydroxymethylglutaryl-CoA reductase, and insulin-like growth factor 2 receptor were significantly increased upon culture with CDS FBS. Moreover, the mRNA levels of sirtuin 1, superoxide dismutase 2, and anti-apoptotic associated gene B-cell lymphoma 2 in frozen-thawed blastocysts were significantly (P<0.05) higher in the CDS FBS group than in the HI FBS group, however, the mRNA level of the pro-apoptotic gene BCL2-associated X protein was significantly reduced. Taken together, these data suggest that supplementation of medium with CDS FBS improves in vitro bovine embryo developmental competence and cryo-tolerance.