• Journal of the Korean Society of Environmental Restoration Technology
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• v.18 no.2
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• pp.1-17
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• 2015

Ecological reservoir is a multifunctional space where provides the functions of retention, animal habitat and improvement of ecosystem health and landscape. The ecological reservoir of Anteo Eco Park located in Gwangmyeong-si has established to functions for water purification, maintenance of healthy aquatic ecosystem. Because the Anteo Eco Park is located in the site where nonpoint pollutant materials flow in, Anteo Eco Park has potential factors which aquatic ecosystem health deteriorates and damages the habitat of golden frog(Rana plancyi chosenica) which is restoration target species. Therefore, the purpose of this study is to suggest the plan to manage the variables which impede the right functions of aquatic ecosystem by understanding the causal loop diagram for the change of water quality environment and the interaction of predator-prey through system thinking. The results are as follows. First, the study showed that the individual number of golden frog which is an indicator species of Anteo Eco Park is threatened by snakeheaded fish, which is an upper predator. Therefore, balanced food chain should be hold to protect golden frog by capturing the snakeheaded fish which is individual number's density is high, and the monitoring management of the individual number for predator(snakeheaded fish)-prey(golden frog) should be performed. Second, the study represented that water pollution and carnification is caused by the sediment as the dead body of the large emergent vegetation in the winter cumulates as sediment. Ecological reservoir in Anteo Eco Park has been managed by eliminating the dead body of the large emergent vegetation, but the guideline for the proper density maintenance of vegetation community is additionally needed. Lastly, the study showed that aquatic ecosystem of Anteo Eco Park where is contaminated from the inflow of nonpoint pollutants affects the individual number's decline of golden frog and snakeheaded fish. Accordingly, the creation of a buffer area and a substitution wetland is needed in the periphery of the Anteo Eco Park to control the inflow of nonpoint pollutants including organic matters, nutrients and heavy metals. This study will be helpful that Anteo Eco Park improves the regional landscape and maintain healthy aquatic ecosystem space for the park visitors including local residents.

• Korean journal of applied entomology
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• v.39 no.4
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• pp.251-258
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• 2000

These studies were conducted to investigate the prey consumption and suppression of cotton aphid and green peach aphid by Chrysopa pallens Ramber as a predator. The 3$^{rd}$ instar of C. pallets fed on 29.8, 77.9, 133.6, and 155.7 individuals of apterous Aphis goussypii Glover a day at 17,22, 27, and 32$^{\circ}C$, respectively. A preovipositing female fed on 73.1 individuals, ovipositing female on 86.6 individuals, and adult male on 69.7 individuals of apterous Myzus persicae (Sulzer) a day at the 27$^{\circ}C$. The functional response curve of the larvae and adults of C. pallens to the densities of A. gossypii indicated Helling’s Type II: the consumption of prey by the C. pallens increased with the prey density but the consumption rate decreased. The attack rate of 3rd instar of C. pallens was the highest among the 2nd instar, 3$^{rd}$ instar, adult male and adult female, and handling time was the shortest. The critical ratio of the predator vs. the prey to effectively suppress the population of A. gossypii by releasing C. pallets eggs was 1 : 4 on red pepper and egg plant, and 1 : 3 on cucumber. Release of second larval stave of C. pallens at the ratio of 1 : 30 of the predator vs. the prey controlled satisfactorily A. gossypii on red pepper, and 1 : 20 on cucumber and tomato. The three-times introduction of the eggs of C. pallens was as effective as four applications of insecticides from mid-June to late September.r.

• Korean Journal of Ecology and Environment
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• v.40 no.4
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• pp.581-585
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• 2007

Swarm formation of Scapholeberis kingi Sars 1903 was observed in a shallow reservoir on 27 May 2007 (Dongpan Reservoir) for the first time. Dense swarms composed of asexual females, only occurred during daytime (13:00-17:00, local time) at the littoral zone. Correlation between density of S. kingi and environmental factors such as water temperature and density of juvenile fish were positively significant. Therefore, it is suggested that the swarming of S. kingi seems to be induced for predator avoidance than increase of mating chance, and water temperature may affect their swarming behavior.

• Korean journal of applied entomology
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• v.42 no.3
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• pp.257-262
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• 2003

Spider mites and their predacious mites were surveyed in an apple orchard where pesticides have not been applied for a long time, to understand the undisrupted predacious mite complex and their role in the controling spider mites. Spider mites occurring in the orchard were different to those in conventional orchards. A few Tetranychus urticae and Panonychus ulmi were observed, while T. kanzawai was abundant during growing season. Four species of phytoseiids, Amblyseius eharai, A. kokufuensis, A. womersleyi and Typhlodromus vulgaris, and one stigmaeid species of Agistemus terminalis were observed from leaf samples in the orchard. Among them, T. vulgaris occurred from early cool season with low T. kanzawai densities through to mid-and late-season. A. womersleyi was observed only during mid-season when T. kanzawai densities were high with hot weather. Amblyseius eharai and A. kokufuensis occured only in early season, but A. terminalis density increased from mid-season and lasted to late-season. The predacious mite complex regulated the density of T. kanzawai approximately under 8 mites per leaf. Tentatively concluding, T. vulgaris is an adaptable predator at lower prey density under cool weather condition, and A. womersleyi is effective predator at higher prey density under hot weather condition. Further, the biological control strategies of spider mites in Korean orchards were discussed based on the predacious mite complex.

• Korean journal of applied entomology
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• v.36 no.3
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• pp.237-242
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• 1997

Comparative studies on suppression possibility with three phytoseiid mite species (An.thly,seiu,sw omersleyi Schicha. A. ,fidIrrc~i.Gs arman and T\ulcornerphlorlrotiiu.s oc~c~idetitaliNs esbit) to the two-spotted spider mite (Te~trrrt~yc.Iir~l~l\ulcorner.i\c .(re Kwh) on kidney bean leaves in field and greenhouse were carried out. In the field experiments with the initial prey -predator ratio of 4 : 1. I0 : I and 20: I . A. ,firllrrcis suppressed successfully the prey populations at all three ratios 17 days after the initial infestation. A. wornc,r-;leyi \uppressed the prey population only at the ratio of 4 : 1, while T. oc~c~ideritcr1iw.s as unable to suppress the prey population at all tested ratios. In the greenhouse experiments with the initial prey-predator ratio of 10: 1, A. jil1ltrci.s could suppress the prey population continuously during the infestation period. A. ~~otnc~r,slceoyuil d suppress the prey population for 13 days after the initial infestation, while T. occie1mttrli.s could suppress the prey population for 8 - 23 days after the initial infestation.

• Korean journal of applied entomology
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• v.39 no.1
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• pp.13-19
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• 2000

This studies was carried out to investigate the natural enemies of citrus red mite, pononychus citri and seasonal occurrence of its major beneficial insects in Yuzu groves (Chonnam province) from 1996 to 1998. Natural enemies against citrus red mite were 9 species including Oligota kashmirica benifica, 0. yasumatsui, Stethorus punctillum, Chrysopa pallens, Propylea japonica, Orius sauteri, Scolothrips takahashii, Amblyseius womersleyi and one unidentified species of thrips (Family: Phlaeothripidae). Among them, Oligota kashmirica benzficu and Stethorus punctillum were found to be dominant species. 0 . kushmirica henifica had 4-5 generations from middle May to middle November with peak in early September. S. punctillum had 3 generations from late May to late October with peak of late June to middle July. Population dynamics between predator ( 0 . kushmiricu benifica and S. punctillum) and prey (Panonychus citri) were quite well synchronized until September but predator density was decreased abruptly after October.

• Korean journal of applied entomology
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• v.48 no.3
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• pp.347-354
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• 2009

This study was conducted on the biological control effects of the natural enemy, Amblyseius cucumeris, against Polyphagotarsonemus latus. The broad mite moved to a new habitat after the carrying capacity of the preferred habitat on the upper leaf has been reached. Population dynamics between predator, Amblyseius cucumeris, and prey, P. latus, were quite well synchronized since the predator followed the movement of the prey. In predation test by Amblyseius cucumeris on P. latus, A. cucumeris fed on 8.8, 15.2, 27.0 and 30.3 individuals/day under the temperatures of 15, 20, 25, and $30^{\circ}C$, respectively. The A. cucumeris larva, protonymph, deutonymph, adult male, and adult female fed on 0.5, 1.6, 5.2, 3.8, and 27 individuals of adult P. latus per day, respectively, under $25^{\circ}C$ condition. The functional response curve of adult P. latus to the densities of A. cucumeris showed Holling's Type II curve. The consumption of prey by A. cucumeris increased with the prey density increase, but the consumption rate decreased. The critical ratio of predator vs. prey effectively to suppress (98% over) the population of P. latus by releasing A. cucumeris was 1:40 on red pepper.

• Ocean and Polar Research
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• v.39 no.4
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• pp.257-267
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• 2017

Although Pacific mackerel (Scomber japonicus) is an important commercial species in Korea, its recruitment mechanism remains largely unknown. Diel vertical positioning of larvae in the water column, which is affected by their specific gravity and the surrounding water density, may help to provide an understanding on recruitment success through predator avoidance and prey availability. The specific gravity measurement on Pacific mackerel eggs and larvae would seem to be essential information necessary to learn about the transport process from spawning to nursery grounds, and consequently the recruitment success. Eggs were artificially fertilized, and larvae were fed with rotifer when their mouths opened 3-4 days after hatching. We conducted the experiment using a density gradient water column to measure the ontogenetic changes in specific gravity from fertilization to 10 days after hatching. Egg specific gravity was stable during most of the embryonic period, but a sudden increase to $1.0249g\;cm^{-3}$ happened just before hatching. However, the specific gravity of newly hatched larvae was much lighter ($1.0195g\;cm^{-3}$), and specific gravity tended to increase continuously after hatching. Comparison of specific gravity with seawater density reveals that eggs and newly hatched larvae can float in the surface layer of the ocean. For the later period of the experiment, the specific gravity showed a cyclic diel pattern: the highest in the evening while the lowest at dawn. The fullness of larval stomach may be responsible for the observed differences in specific gravity, because stomach fullness was lower (40-60%) at midnight, and higher (80-85%) in evening. The diel pattern of specific gravity might provide clues regarding how larvae match the diel vertical migration of prey organisms.

• Korean Journal of Ecology and Environment
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• v.37 no.4 s.109
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• pp.385-393
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• 2004

The herbivorous rotifers community (Brachionus spp.) and population dynamics of the predator rotifer (Asplanchna spp.) in three tributaries (Kumho R., Nam R., and Hwang R.) of the Nakdong River were evaluated on biweekly intervals from Jan. 2001 and Dec. 2002. High abundance of the herbivorous rotifers (peak density: - ca.>1000 Ind. $L^{-1}$) was observed from two tributaries (Kumho R. and Nam R.) during the spring and fall seasons, respectively. The high peaks of herbivorous rotifers were not evident in one tributary (Hwang R.). Among the herbivorous rotifers, brachionid rotifers (Brachionus spp. consisting of 7 species) were the characteristic rotifer community in this study. Brachionus spp. tended to occur together with the other perennial species, Asplanchna. Asplanchna was also present while two species of B. angularis and B. calyciflorus were highest in density. Subsequently, two populations (B. angularis and B. calyciflorus) rapidly declined, becoming rare after high peaks of Asplanchna occurred, except in one tributary (Hwang R.). We found community shifts in rotifer groups in mid-spring and mid-fall at the study site. The Asplanchna population could be appeared to play an important role in regulating the rotifer community and total plankton biomass in spring and fall at high trophic levels.

• Journal of Environmental Science International
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• v.16 no.2
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• pp.227-232
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• 2007

Water pollution in enclosed water bodies such as lake and river has become a serious problem over the world. Domestic wastewater is responsible for more than 60 % pollution load in public water area in Korea. Effluent of the treated domestic wastewater at low removal level is abundantly fed rivers and lakes and thus be an serious cause of lake pollution. Therefore, effective implement of domestic wastewater treatment in basin of lake and river must be prepared. The septic tank is one of the effective domestic wastewater treatment equipment and used in individual treatment for a unit of household, The purpose of septic tank as biological treatment system is simultaneously to remove BOD, T-N, T-P and reduce turbidity from influent. Accordingly, the appropriate control of functional microorganisms is important subject for the establishment of stability and economy of the biological treatment method. Especially, microanimals as a high-ranked microorganisms of food-chain are important, because microanimals control the other microorganisms especially various bacteria and effect on function of treatment. Therefore, it is necessary that functional predator like rotifers are attached in wastewater treatment process. In this study, the methods for attachment high density the rotifer to and improvement of transparency in the effluence by a dense rotifer was examined using laboratory scale biological treatment reactor simulated septic tank and real one.