• Journal of Korean Society of Forest Science
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• v.107 no.4
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• pp.486-496
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• 2018

Pine wilt disease (PWD) in Gyeonggi province was first detected in Gwangju in 2007, and ever since has caused extensive damage. Insect vector and host tree in Gyeonggi province are Monochamus saltuarius and Pinus koraiensis, respectively, which are different from the southern region that consist of Monochamus alternatus and Pinus densiflora. Consequently, spread and mortality characteristics may be different, but our understanding is limited. In this research, we utilized the spatial data of newly infected trees in Gyeonggi province from 2008 to 2015 to analyze how it is related to various environmental and human factors, such as elevation, forest type, and road network. We also analyzed the minimum distance from newly infected tree to last year's closest infected tree to examine the dispersal characteristics based on new outbreak locations. Annual number of newly infected trees rapidly increased from 2008 to 2013, which then stabilized. Number of administrative districts with infected trees was 5 in 2012, 11 in 2013, and 15 in 2014. Most of the infected trees was Pinus koraiensis, with its proportion close to 90% throughout the survey period. Mean distance to newly infected trees dramatically decreased over time, from 4,111 m from 2012 to 2013, to approximately 600 m from 2013 to 2014 and 2014 to 2015. Most new infections occurred in higher elevation over time. Distance to road from newly infected trees continuously increased, suggesting that natural diffusion dispersal is increasingly occurring compared to human-influenced dispersal over time.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.52 no.2
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• pp.129-133
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• 2007

To breed virus resistant rice variety, developing an efficient screening method is the most important. Two screening methods such as field screening and tray screening method have been used, but the efficiency of the field screening method is too low because of environment factors and the that of the tray screening method is good but screening capability is limited with only $200{\sim}300$ lines per year. To overcome those problems, mass screening method using screen house was developed. Barely as host plant of vector insect was grown in screen house in winter season. Then viruliferous insects are spread in the first spring of the initiation year and sustain them annually. Screening of virus resistance was tested two times in a year, the first screening was from April to June and the second from July to September. The virus infected rate of each susceptible varieties was increased to 92% for RSV and 100% for RDV from the second year. Also, this method can evaluate as many as $1,500{\sim}2,000$ pedigree lines in one time compared with the tray screening method. The result indicates that the mass screening method using screen house, which combines the advantages of the field and tray screening methods, is proven to be more efficient and reliable.

• Korean journal of applied entomology
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• v.16 no.2 s.31
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• pp.79-86
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• 1977

Four experiments were carried out under farmer's field conditions to determine economic threshold levels of major rice pests aad attempt a reduction in the number of insecticide applications. In the experiments were included check treatments, insecticide schedules representing the official recommendations to farmers, and several corrective treatments. A careful record was kept of insect pest densities and disease incidence. i) In the north at Suweon and Icheon where Chilo suppresalis. (Walk.), the striped rice borer, was active in the first generation, no significant yield differences were obtained between plots receiving several insecticide applications and those left totally unprotected. The mean yields were high (5.2-7.6t/ha). ii) First generation borer activity rising to $8.6\%$ injured tillers was below the economic threshold since no yield reduction was recorded in either japonica varieties or the high-yielding Tongil variety. iii) Evidence was obtained thst berer damage was made good by replacement of infested tillers (compensatory growth), C. suppressalis populations were always low in the second generation. iv) The experimental results obtained at Suweon and Icheon do not justify the present official recommendations of 6-7 pesticide applications. v) further south at Iri a substantial yield reduction occurred due to an early outbreak of stripe disease transmitted by Laodelphax striatellus (Fallen), the small brown planthopper; a mean of 1-2 individuals/hill was recorded immediately after transplanting. C. suppressalis probably contributed to this yield reduction. vi) Several applications against the vector failed to prevent the rapid spread of stripe to the susceptible variety in the Iri experiment: in surrounding fields the resistant Tonsil varivety was ralatively unaffected. vii) Pests of lesser importance were Nephotettix cinctieps (Uhler), Nilaparvata lugens (Stil), Sogatella furcifera (Horv..), and leaf miners.

• Journal of Life Science
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• v.17 no.8 s.88
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• pp.1129-1134
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• 2007

In the previous our study, a cDNA that encodes protein disulfide isomerase from Bombyx mori (bPDI)was isolated and characterized. bPDI has an open reading frame of 494 amino acids contained two PDI-typical thioredoxin active site of WCGHCK and ER (endoplasmic reticulum) retention signal of the KDEL motif at its C-terminal. Recent studies have demonstrated that misfolded proteins are accumulated in many diseases including Alzheimer’s, goiter, emphysema, and prion infections. bPDI was over-expressed or knock-downed in Sf9 cells to study the relationship between bPDI expression and protections against protein misfolding. bPDI gene was cloned in insect expression vector pIZT/V5-His for over-expression and bPDI double-stranded RNA (dsRNA) was generated for knock-down. Over-expression of bPDI significantly improved survival rate, but bPDI dsRNA transfection significantly reduced survival rate after 48 hours exposure. In mock-transfected or wild-type cells had no significant effect. The results support the view that bPDI is one of the important intracellular components for cell protect mechanism, especially, against ER stress such as protein misfolding.

• The Journal of Korean Society of Virology
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• v.28 no.3
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• pp.247-265
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• 1998

To determine the sequence and expression of the VP7 gene of Korean isolates (CAU-9), viral RNA was purified and used for cDNA amplification by RT-PCR. The VP7 cDNA was cloned, sequenced, and expressed using baculovirus expression system. The result showed that the sequence homologies CAU-9 compared with foreign isolated strains Wa, 417, TMC-II, 95B and SA11 were ranged from 74.0% to 95.1 % of nucleotide sequence and 35% to 43% of amino acid sequence, respectively. High homology of CAU-9 was observed in Japanease isolates 417 (nucleotide sequence homology was 95.1% and amino acid sequence homology was 43%). To express VP7 gene, the VP7 cDNA was cloned into pCR-Bac vector and inserted into the genome of baculovirus adjacent to the polyhedrin promoter by cotransfection of Spodoptera frugiperda (Sf9) insect cells with wild type baculovirus DNA. In antigenic analysis of Sf9 cells inoculated with the recombinant VP7, immunofluorescence assay revealed positive for viral antigens. In metabolic labeling of Sf9 cell lysates infected with recombinant baculoviruses, it was revealed that the protein of 34 kDa was expressed. The limited study of expressed VP7 protein inoculated with guinea pigs failed to elicit neutalizing antibody. As a results, the sequence analysis and expression of VP7 protein of rotavirus CAU-9 isolated from an infant in Korea could permit the conformation and development of virus like particles which may be useful in designing vaccine strategy.

• The Korean Journal of Zoology
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• v.38 no.3
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• pp.340-347
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• 1995

We have used two kinds of P element constructs, Pc[(ry+)B] and p[(ry+)$\Delta$SX9], for genetic transformation by microinjection of D. melanogaster. Pc[(ry+)B] construct carrying the rosy gene within an autonomous P element was injected into a true M strain caring the ry506. mutation. The source of transposase for microinjection and transformation was provided by a P element helper plasmid designated p-$\Delta$2-3hs$\pi$, which was co-injected with nonautonomous P[(ry+)$\Delta$SX9] construct into same ry506 M strains. A dechorination method was adopted and 35 independent transformed lines were obtained froin 1143 G0 Injected (35/1143). About 20% of the injected embryos eclosed as adults. Among G0 eclosed flies, approximately 40% exhibited eye color that was similar to wild-type (ry+), but about 60% of fertile G0 transformed lines appeared to have no G1 transformants. Therefore it is unlikely that G0 expression requires integration of the rosy transposon into chromosomes. Pc[(ry+)B] and P[(ry+)$\Delta$SX9] constructs were found to be nearly same in the frequency of element-mediated transformation. On the basis of these results, nonautonomous P elements constructs could he used as same effective vectors in P element-mediated transformation for introducing and fixing genes in insect populations.

• Korean Journal of Environment and Ecology
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• v.29 no.4
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• pp.590-598
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• 2015

Despite various control methods for pine wilt disease, the disease has been increasing at an alarming rate every year in Korea. Still there is a lack of research on the problems of the current methods used to curb the disease. One main method to control pine wilt disease is fumigation for eliminating the larva of the pine sawyer beetle (Monochamus alternatus) which is known as the vector insect for pine wilt disease. We surveyed and analyzed the amount of destroyed uninfected trees in the fumigated area by studying 32 survey plots ($100m^2$) in Miryang city. The destroyed trees' crown area was estimated by induced regression between root collar area and crown area of the remaining trees (coniferous tree: $R^2=57.4$, deciduous broad-leaved tree: $R^2=63.8$). According to the analysis results, the infected trees (cut trees) were 18.7% and cut trees which were not infected were 35.5% of the total tree population of the study area on the basis of total crown area. In case of pine trees, 8.4% of uninfected trees were cut off but 62% of uninfected deciduous broad-leaved trees including Quercus spp. were affected and damaged during the fumigation process. Since these broad-leaved trees dominate the sub-canopy layer of the forest, this indiscriminate interruption of broad-leaved trees has the adverse effect of depriving the public benefits such as shadow, a cooler weather, controlling humidity, etc.

• Korean journal of applied entomology
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• v.54 no.4
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• pp.443-448
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• 2015

The attractant effect to Platypus koryoensis (Murayama), an insect vector of Korean oak wilt disease, was determined using a multi-funnel trap and trap logs treated with ethanol and ethanol extract of the bark of the Mongolian oak Quercus mongolica (Fisher). The number of entrance holes in ethanol and bark ethanol extract treatments was higher than that in the control (blank bottle). However, the number of entrance holes in ethanol and bark ethanol extract treatments was not significantly different. The number of entrance holes in the logs increased with increase in diameter of the logs. The lower part of the trap logs had significantly more number of entrance holes than that in the upper part (p < 0.05). The lower part of trap logs tends to be rarely exposed to direct sunlight resulting in desiccation of the logs, which in turn provides good conditions for microbial growth, a food source for P. koryoensis. The results show, that ethanol could be used effectively in the monitoring and maintenance of P. koryoensis because of the cheaper cost of ethanol than bark ethanol extracts, and thus, having a higher economical advantage. Further research of oak bark ethanol extracts is necessary to improve its efficiency.

• Korean journal of applied entomology
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• v.54 no.4
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• pp.419-423
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• 2015

Small brown planthopper (SBPH), Laodelphax striatellus, gives a lot of damage to the rice by insect vector of rice stripe virus (RSV). This study compared the RSV acquisition and infection rates according to wing form, sex, and life stage of SBPH. The RSV acquisition rate in macropterous and brachypterous was 60.7% and 63.1%, respectively. The RSV acquisition rate by sex was 61.9% in female and 52.2% in male. However, there was no difference in significance. The RSV acquisition rate of nymphs and adults was 51.2% and 58.7%, respectively. The RSV infection rate by wing form was 53.3.% in macropterous and 48.2% in brachypterous. According to life stage, nymphs was 38.2% and adults was 42.6%. There was no difference in significance. On the other hand, female and male of RSV infection rate was 50.5% and 22.3%, respectively. There was a significant difference. Additionally, developmental periods of SBPH by RSV infection, the longest when inoculated with RSV-infected SBPH in healthy rice, while the shortest when inoculated healthy SBPH in healthy rice.

• Korean journal of applied entomology
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• v.5_6
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• pp.1-7
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• 1968

The present investigation was initiated to find out the possible insect vector of the paulownia witches'-broom virus disease. 1. Among a number of piercing-sucking mouth type insects that were feeding on the witches'-broom infected Paulownia leaves, the tobacco leaf bug, Cyrtopeltis tenuis REUTER, was most abundant. Eggs, nymphs and adults of Cyrtopeltis tenuis were observed from the mid-August through the end of October. 2. It was found that Paulownia witches'-broom virus is transmitted by Cyrotopeltis tenuis. 3. On young Pnulownia plants, first symptom appeared twenty days after exposure to virus-bearing colonies of Cyrtopeltis tenuis. Forty days after exposure to these viruliferous insects, the characteristic symptom of Paulownia witches'-broom was apparent. 4. Paulownia witches' -broom virus was also transmitted by Cyrtopeltis tenuis to calendula and morning glory. No app"rent symptom was observed from tomato, carrot. aster, zinnia, cosmos, soybean and plantago at least until sixty days after exposure to the viruliferous colonies of Cyrtopeltis tenuis. 5. Calendula and morning glory appear to be highly suitable test plants for Paulownia witches'-broom vims because of their relatively short incubation period and distinct symptom appearance.