• Journal of Sericultural and Entomological Science
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• v.19 no.1
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• pp.25-32
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• 1977

The flacherie (FV) and Ina-flacherie (Ina-FV, named arbitarily) viruses of the silkworm, Bombyx mori was isolated from infectious larvae. Two types of infectious particles were purified by sucrose density gradient centrifugation. Some properties of the purified particles were investigated. Electron micrographs showed that FV and Ina-FV were spherical particles with diameters of 27nm and 20nm, respectively. The sedimentation coefficient of Ina-FV was 80S.

• Korean journal of applied entomology
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• v.32 no.1
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• pp.105-114
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• 1993

Series of studies were conducted to establish biological and chemical control method for Meloidogyne spp to medical herbs by applied of nematophagous fungi, Arthrobotrys spp, Fusarium spp, and egg parastic fungi, Paecilomyces lilacinus were applied for root-knot nematodes on medicinal herbs, Paeonia albiflora, Codonopsis lanceolata, Cnidium officinale. The results are as follow. In pot experiments, The no. of root gall and egg mass and larvae of Cnidium officinale. The results are as follow. In pot experiments. The no. of root gall and egg mass and larvae of Cnidium officinale, Codonopsis lanceolata, Paeonia japonica lowered in P. Lilacinus treated plots compare to untreated control plots. But A. thaumasia F. oxysporum treated plots were less effective. Effect of egg parasitic fungi and chemical treatment at divided root of Paeonia japonica after sterilized in pot were increased in the fresh weight, root weight, control effect in P. lilacinus treated plots as chemical, Carbo G treated plots compare to untreted control plots. I field experiment, the number of root gall, egg mass and nematode density of Paeonia were also suppressed in P. lilacinus treated plots. It was very effective continuous 2 years and transplanting time on Paeonia japonica infested soil with the M. hapla in field in both region, Chillgok and Euisung treated P. lilacinus as chemical treated plots. Soaking effect of insecticide for Paeonia japonica at diving shoot before transplating in pot were effective for 12hours immersion into 1,000 ppm of Benlate T + Mep Ec, Benlate T + Fenthion EC in pot and field Experiment. In the Examination of fungi activily on P.japonica field 1 year after soil treatment, Number of spore of P. lilacinus were 1,000~1,300 in 3 region except Euisung.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.54 no.3
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• pp.262-270
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• 2018

We examined the characteristics of egg and larval distributions and catch changes of anchovy in relation to abnormally high sea temperature in the South Sea of Korea in summer 2015 and 2016. The densities of anchovy eggs and larvae in the southern coastal region were lower in July-August 2016 than in July-August 2015. In particular, anchovy eggs and larvae (approximately 5 mm TL) were rarely observed in the coastal region in August 2016 due to the abnormally high SST (up to $28^{\circ}C$), which was above the optimum spawning temperature of anchovy. The catch of non-swimming stage (< 2 cm TL) larval anchovy was lower in July-August 2016 than in July-August 2015. The decreased catch of larval anchovy in July-August 2016 could be attributed to decreased spawning density in June-July 2016. In contrast, the catch of swimming stage (> 2 cm TL) anchovy was increased in July-August 2016. In the summer of 2016, prominent sea temperature near the southern coast of Korea and sea temperature higher than $30^{\circ}C$ in the offshore region of the South Sea of Korea could greatly enhance the retention of swimming anchovies in the coastal fishing grounds.

• Journal of the Korea Organic Resources Recycling Association
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• v.20 no.1
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• pp.50-60
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• 2012

This study was carried out to evaluate the ecotoxicological effects of Alum and Ferric chloride on the population of Eisenia fetida in vermicomposting of sewage sludge. Using contact filter toxicity test, it was shown that LC50 of Alum and Ferric chloride on adult Eisenia fetida were 457.4 mg $kg^{-1}$ and 1,665.2 mg $kg^{-1}$, respectively,which meant Ferric chloride had much higher acute toxicity on earthworm than Alum. Alum didn't affect on cocoon production, hatchability and number of hatched larvae of Eisenia fetida. Ferric chloride didn't have any efects on number of hatched larvae per cocoon, but reduced cocoon production and hatchability. Larval density of next generation was reduced by the food containing Alum and Ferric chloride. Above results indicated that the Alum and Ferric chloride could be one of the hazardous materials that made extinction of earthworm population when the sewage sludge treated with Alum and Ferric chloride was supplied to the earthworms.

• Korean Journal of Environmental Biology
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• v.25 no.4
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• pp.378-384
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• 2007

Some of ecological factors and the early life history of endangered freshwater fish, Pseusobagrus brevicorpus, were investigated to proliferate artificially and to restore the population by release seedlings. The density of population in restricted area by small scale dam was 1.25 ind. $m^{-2}$, and the low capacity for reproduction having 200$\sim$250 eggs ind$^{-1}$. were thought to be a reason of this endangered situation. From the result of induction of natural spawning in aquarium after hormone injection it was considered that the spawning substrate would be aquatic plants with slender branches. The hatching was observed after 50 hrs after fertilization and the larvae showed aggressive behavior. Yolk was almost absorbed 3 days after hatching, and the larvae shaped tad-pole grew up to fry after 30 days. We discussed on the strategies for conservation of this species according to those results from investigation on ecology and early life history.

• Journal of Aquaculture
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• v.21 no.3
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• pp.125-132
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• 2008

Seed production of olive flounder Paralichthys olivaceus was performed in a pilot RAS. The growth of juvenile olive flounder and changes in water quality were monitored for the entire production period. The pilot RAS consisted of 8 circular culture tanks($4.0mD{\times}1.0mH$), 2 trickling biofilters($1.7mD{\times}2.0mH$), 2 protein skimmers ($0.8mD{\times}2.5mH$), and 4 sedimentation chambers($0.7mD{\times}1.5mH$). The culture surface area was about $100.5m^2$ and the actual working volume was about $106.9m^3$. As many as 300,000 fertilized olive flounder eggs were initially distributed into 2 culture tanks with the water temperature at $19.0^{\circ}C$. Live feeds such as rotifers and Artemia nauplii were fed until the 32nd day after hatching, and a commercial diet was fed from the 19th day to the end of the experiment. After 70 days, 150,256 juveniles with a body length of $65.8{\pm}3.9mm$ were produced in the RAS, with a daily growth rate for body length of 4.7%/day. At this time, the final culture density was 1,495 individuals $m^{-2}$, and 13.6 L of makeup water, 0.071 kW of electricity and 0.025 L of diesel fuel were used to produce a juvenile olive flounder. During metamorphosis of the larvae, the TAN concentration increased to 0.99 mg/L, which made the larvae sensitive to result in some mortality. However no more massive mortality occurred at the juvenile stage after metamorphosis even at a TAN concentration of 4.25 mg/L and a ${NO_2}^{-}-N$ concentration of 2.45 mg/L.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.26 no.3
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• pp.258-265
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• 1993

Monthly changes in the occurrence and infection levels of a parasitic copepod Acanthochondria yui(Poecilostomatoida, Chondracanthidae) on a gobiid fish Acanthogobius flavimanus were studied for a year from April 1990 to March 1991. This parasite was not found on the fish for four months from September to December. Prevalence of the parasite increased from $2.9\%$ in January to $88.9\%$ in June. Relative density and mean intensity also increased from January to June. Prevalence of A. yui increased with host size. A. flavimanus samples were never found carrying A. yui larvae of three copepodid stages(CI to CIII), although a few CIV and CV larvae were identified from April and May samples. This indicates that A. flavimanus was not the sole host of A. yui. Adult females and copepodites of A. yui were usually found in the gill arch($74.8\%$) and gill filament($80.6\%$), respectively. This suggests that copepodites select the gill filament as the most suitable place on their host A. flavimanus, and the adult females move toward the gill arch.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.54 no.3
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• pp.298-310
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• 2021

Freshwater eel Anguilla japonica is a commercially important species in East Asia. However, given the continuously decreasing resources due to many problems as climate change, habitat destruction and overfishing, mass seed production is crucial. In particular, the eel larvae present a unique life history, spending prolonged periods in the Pacific Ocean. Therefore, finding suitable feed that lasts through the long larval stages is rather difficult. In the present study, we histologically observed the development of digestive organs for 50 days after hatching (DAH). The endogenous reserves were completely absorbed at 7 DAH, and the first exogenous feeding started thereafter. The teeth appeared at 4 DAH and dramatically changed from needle-like to broad-based types by 50 DAH. The intestine remained as straight gut until 50 DAH. The intestinal cilia appeared first at 6 DAH and their density continuously increased thereafter. Interestingly, goblet cells appeared in the intestine, but not in the esophagus, where these cells are commonly observed in other teleosts. In addition, high amounts of eosinophil substances, assumed to be zymogen granules, accumulated in the pancreas, suggesting a specific digestive strategy of this species. Overall, these observations largely update the previous reports and can be useful to improve A. japonica seed production.

• Korean journal of applied entomology
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• v.40 no.1
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• pp.45-45
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• 2001

Development and predation of an aphidophagous gall midge, Aphidoletes aphydimyza (Rondani) , on the green peach aphid, Myzus persicae Sulzer, were studied under laboratory and greenhouse conditions. The developmental threshold temperature of the gall midge larvae was estimated to be $13^{\circ}C$. Larval and total developmental periods were 5.3 and 29 days at 25 $\pm$$2^{\circ}C$. The gall midge attacked more aphids as increasing density of peach aphids, and consumed 4 out of 10 peach aphids per day in a petri dish (9 cm in diameter) at maximum. In green house, the gall midge could control the density of the green peach aphids efficiently with a delayed density dependent-like pattern.

• Ocean and Polar Research
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• v.23 no.3
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• pp.245-253
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• 2001

To investigate the community structures and the their seasonal variation of phytoplankton and zooplankton, a study was conducted at 6 selected stations during the period from April 1999 to October 2000 in the marine ranching ground off Tongyeong. One hundred ninety species of phytoplankton were identified, including 146 diatoms, 38 dinoflagellates, 4 silicoflagellates and 2 euglenophytes. Phytoplankton standing crops varied extensively by months and stations, ranging from $3.0{\times}10^4\;cells/l\;to\;1.0{\times}10^6\;cells/l.$. The dominant species varied from the vertical distribution as well as seasonal changes. In April and July 1999, Skeletonema costatum and Ceratium fusus were predominant in both the surface and the bottom water columns. Leptocylindrus danicus was the dominant species in April and June 2000, and Thalassiosira spp. were also predominant in bottom waters in June 2000. Pseudonitzschia pungens and Chaetoceros spp. were the dominant species at both surface and near bottom waters in August and October 2000, respectively. Zooplankton abundance was comparatively high in April and July in 1999, and April, June, and October in 2000, but extremely low in November 1999. The density of dominant zooplankton was higher in 2000 than in 1999. Copepods were the most predominant group except for July 1999 when the bivalve larvae showed extremely high abundance. Acartia omorii and Oithona similis were the dominant or subdominant copepod species mainly in April 2000, and June/July, while O. davisae and O. plumifera had peaks in August and October 2000. Corycaeus affinis and Paracalanus sp. also showed higher peaks in April and June (or July), even though they occurred in all sampling time. Centropages abdominalis occurred abundantly only in April 1999. Oikopleura dioica, a gelatinous zooplankton, was another important zooplankton, showing high density in all samples except in July 1999.