• Korean Journal of Ecology and Environment
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• v.47 no.1
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• pp.24-31
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• 2014

This study was conducted to clarify the seasonal and elevational pattern of herbivore's feeding pattern in a temperate deciduous forest. We investigated the herbivore's feeding activity for three years (2011~2013) at three survey sites in Mt. Jirisan National Park (Piagol, Siamjae, Nogodan). We selected target tree species based on the dominance across the sites (Quercus, Acer, Rhododendron and Carpinus) and scored herbivore's feeding activity every one or two weeks from April to June using leaf damage index. We found that the herbivory started early at the low elevation site (Piagol, ${\approx}300m$), and the highest feeding activity occurred at the mid elevation site (Siamjae, ${\approx}900m$). At the highest elevation site (Nogodan, ${\approx}1300m$), the herbivory started late, but the total feeding activity accumulated quickly. Compared to the breeding time of Varied tit, an insectivore bird, it was overlapped with the feeding activity period of herbivores, suggesting close interaction among plants, insects and birds in this deciduous forest. We suggested a need of long-term monitoring of this tri-trophic interaction since duration of herbivore activity can be changed followed by climate change.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.32 no.3
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• pp.302-309
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• 1987

One hundred rice varieties were tested for their level of resistance to sheath blight disease at adult plant stage in field condition through 1984 to 1986. Rice plants were grown under ordinary seasonal culture and inoculated by k-2 fungus isolate during three years. k -1 isolate was also inoculated separately in 1984 and test under late seasonal culture was conducted in separate field in 1985. Degree of damage by the disease observed at 25 days after heading was used to identify the level of resistance of the rice varieties tested. Varietal differences of degree of damage were significant in five tests during three years, and the genotypic variance of degree of damage was always higher than environmental variance among varieties tested. Positive correlations between testing years, between cultural seasons, and between isolates inoculated were found in degree of damage of varieties tested for two or three years continuously. Degree of damage by the disease was correlated negatively with heading date of rice varieties except 1984 tests. Thus, the level of resistance should be compared among the variety group having almost same heading date in field condition, and late and extremely late variety groups should be tested for their level of resistance under appropriate environmental condition. Gayabyo, an early heading variety, and SR9713-54-3, a medium heading breeding line, showed consistent lower value of degree of damage during two or three years. These two varieties were selected as moderate resistant germplasm.

• Korean Journal of Environment and Ecology
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• v.15 no.3
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• pp.267-275
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• 2001

This study was conducted to investigate the characteristics of bird community and to suggest a proper way how to manage and protect bird community in Mt. Paldal, Suwon City. The survey was carried out by line transect method from March 1992 to February 1993, and from October 1998 to August 1999. Twenty-seven birds were recorded, and these birds were also classified into 14 species for residents, 8 species fur summer visitors, 4 species for winter visitors and 1 species fur passage migrant in 1992. Twenty-one birds were recorded, and these birds were also belonged to 16 species fur residents, 2 species fur summer visitors, 2 species for winter visitors and 1 species for passage migrant in 1999. In 1992, seasonal change of number of species and individuals showed a typical pattern of temperate deciduous forests, however, seasonal pattern in 1999 was somewhat differed from that of temperate deciduous forest. According to data of migration habits of bird community in same months, percentage of residents were higher in 1999 and that of summer visitors were higher in 1992. In guild analysis of breeding bird community, bush-nesting and foraging guild that utilize the bush layer as nest and food resources showed the decreasing number of species and individuals, also summer visitors did the same decreasing trends from 1983. Therefore, it should be suggest that protection of bush layer for inhabitation of bush-nesting and foraging guild and summer visitors, and it will be considered that construction of green net-work among urban forests such as Mt. Kwanggyo, Mt. Chilbo, Mt. Paldal, Mt. Sukgi and Mt Yeogi in Suwon City.

• Korean Journal of Environment and Ecology
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• v.22 no.6
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• pp.648-657
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• 2008

This research was conducted to investigate the breeding density and seasonal food items of the magpies in Jeju Island and the near-manned islets. The examination of nest distribution to determine breeding density was performed during breeding season from February 2006 to April 2008, and that of food items from May 2006 to February 2008. A total of 2,113 nests were found across Jeju Island, the average density was $1.33\;nest/km^2$, and the magpies were distributed up to 600 meters above the sea level. The nest density was the highest in the central areas of Jeju Island, with 688 nests at $3.61\;nest/km^2$, while that in the eastern areas was the lowest, with 214 nests at $0.66\;nest/km^2$. In terms of the number of nests depending on the height above the sea level, 1,172 nests, which was equivalent to the density of $1.85\;nest/km^2$, was observed below 100m and highest among the intervals of height, but 16 nests found at 500-600m were the lowest, corresponding to $0.20\;nest/km^2$. The number of nests found in the manned islets near Jeju Island was eight in Biyang-do with the density of $15.38\;nest/km^2$, nine in U-do with $1.49\;nest/km^2$, and one in Gapa-do with $1.15\;nest/km^2$, whereas none of nests were observed in Mara-do. The contents of stomach consisted of 17 types of prey sources including countless bones, eggshells, plants, and seed, most of which were the individuals of the order Coleoptera. In spring and summer, the foraging frequency for invertebrate animals such as insects was high, but less than 30% in winter. In contrast, the magpies preyed upon plants and seeds at the frequency of 10% and 30%, respectively, in spring, while the foraging frequencies for both of them were 100% in winter and higher than any of other seasons. Eggshells and bones of birds were also detected infrequently. If the density of the magpies, which may play role as the upper predator within the ecosystem, increases, it would be expected to affect directly the reduction of the number of the species and population of endemic animals such as small birds and reptiles, etc. Therefore, it is considered that long-term monitoring for the density of the magpies and precaution is prerequisite to minimize adverse effects on ecosystem.

• Parasites, Hosts and Diseases
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• v.23 no.1
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• pp.139-150
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• 1985

In order to determine the seasonal prevalence and population density of vector mosquitoes in Kyungpook Province, a survey based on average numbers of female mosquito per trap-night, were carried out during the period from May to November in 1984. Among the 34, 571 mosquitoes collected in Kyungsan county in animal shelters and human dwellings by light traps, approximately 45.0 per cent were Culex tritaeniorhynchus, 34.0 per cent Culex pipiens pallens, and 19.0 per cent Anopheles sinensis. By comparison, distribution of mosquito species in Ankang town, in which Japanese encephalitis had been reported in the past, were quite different and A. sinensis was the most abundant species, being constituted in 75.8 per cent, followed by C. tritaeniorhynchus(23.2 per cent), and C. pipiens pallens(O.6 per cent). In the general pattern of seasonal prevalence, C. tritaeniorhynchus first appeared in mid-June, and trapped in large numbers during the periods from mid-August to early September, showing a simple sharply pointed one-peaked curve, while C. pipiens pallens was found to be active through almost the entire season showing irregular curves with several peaks. The trend of seasonal distribution of A. sinensis was similar to that of C. tritaeniorhynchus, but the earliest dates of appearance and disappearance differed from that of C. tritaeniorhynchus. The results of hourly catches of mosquitoes by human baited traps have clearly shown the differences in the biting rhythm among the vector mosquitoes of this Province, such as the facts that C. tritaeniorhynchus and A. sinensis are rather constantly active all through a night with more or less inconspicuous peaks twice a night, while C. pipiens pallens exhibits an irregular curve, and the numbers of A. vexans nipponii, C. vagans and Armigeres subalbatus are very small and are not sufficient for estimating the biting rhythm. Four genera and fourteen species of larval mosquitoes collected from eighteen kinds of habitats which classified according to the categories followed by Bates (1949). The main breeding sites contributing to peak C. tritaeniorhynchus adult densities in this surveyed areas were evidently ricefields, ground pools, puddles and swamps and marshes, etc. Summarizing the results, this study indicated that the highest population density of C. tritaeniorhynchus was encountered in late August and early September, showing a simple sharply pointed one-peaked curve.

• Journal of Photoscience
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• v.9 no.2
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• pp.255-257
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• 2002

In birds, the photoperiodic seasonal breeding involves encephalic photoreception at the initial step of triggering the well-known endocrinal cascade. Especially in Japanese quail (Coturnix coturnixjaponica), the reproductive neuroendocrine function responds to a single long day, and hypothalamic regions are known to be important for the reproductive response. However, little is known about where and how the light and time signals are integrated to detect daylength information and transduced to the endocrinal responses. To gain insights into this issue, we are interested in the c-Fos expression in the hypothalamus of the Japanese quail. Meddle and Follett (1997) previously identified two hypothalamic regions where c-Fos-like immunoreactivities were induced in response to a long day by using an antibody to carboxyl terminal region of human c-Fos (Lys$^{347}$ -Leu$^{367}$ ). In the present study, we used a different anti-c-Fos antibody recognizing a region from Lys$^{128}$ to Ala$^{152}$ of human c-Fos, and found in long-day- stimulated quails many c-Fos-like immunoreactive nuclei localizing within two regions, nucleus anterior medialis hypothalami and nucleus periventricularis hypothalami, which are distinct from those identified in the previous study. Then, we focused on the difference in the cross-reactivities of the antibodies used, and determined the whole coding sequence of quail c-Fos to compare the antigenic sequences of the two antibodies with the amino acid sequence of quail c-Fos. We found that the antibody we used would recognize quail c-Fos more specifically than that used in the previous study.

• Journal of Ecology and Environment
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• v.35 no.1
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• pp.41-50
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• 2012

To determine the movement patterns, home range, and use of structural features of captive-bred one- or two-year-old Amur ratsnake (Elaphe schrenckii) juveniles in the natural habitat, we radio-tracked a total of 11 juvenile snakes in a mountain valley in Chiaksan National Park, South Korea, between August 21 and September 20, 2010 and between June 13 and July 13, 2011. During the first week of the release, most juveniles moved short distances, daily, but they increased their distances after the first week. The body weight of the juveniles was negatively related with the movement rate (dividing the number of movements by the number of relocations), which was positively related with the mean daily distances moved and the size of both a kernel 50% and 95% home range. During the study period, the juveniles moved daily, approximately 17 m, and the size of the minimum convex polygon and the 50% and 95% kernel home ranges were 1.8 ha, 0.4 ha, and 3.0 ha, respectively. The released captive-bred juveniles were more frequently confirmed underground or on the ground rather than on rocks or on trees. Our results suggest that the body condition of released individuals, the seasonal time of the release, and the existence of available prey and shelters in the habitat should be carefully considered when releasing captive-bred Amur ratsnake juveniles for the rehabilitation of field populations.

• International Journal of Industrial Entomology and Biomaterials
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• v.33 no.2
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• pp.92-95
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• 2016

The black soldier fly is economically important because its prepupae are used as feed for many animals, including fish and swine. In Korea, black-soldier-fly farms have attempted to increase annual breeding and mass egg production for use in animal feed, as well as the decomposition of organic waste. Such efforts require an understanding of optimal mating and oviposition techniques. Specifically, adult densities and cage size may both improve the efficiency of mass egg production. Our study used four sizes of nylon cages ($1.0{\times}1.0{\times}2.5m$, $1.5{\times}1.5{\times}2.5m$, $2.0{\times}2.0{\times}2.5m$, $2.5{\times}2.5{\times}2.5m$) and three density treatments (4 kg, 8 kg, and 10 kg of pupae) to investigate optimal habitat size and adult density. We found that cage size (independent of density) did not significantly influence female fecundity (number of egg clutches and egg weight), whereas higher densities increased egg number and weight regardless of cage size. Thus, we recommend manipulating adult density to enhance productivity in commercial black-soldier-fly farming. However, we also propose further detailed research to develop methods that account for seasonal changes and environmental conditions, as climatic variables (temperature, sunlight) likely influence female fecundity as well.

• Development and Reproduction
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• v.7 no.1
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• pp.35-40
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• 2003

Gonadotropin releasing hormone(GnRH), which is secreted from the hypothalamus, has a pivotal role in the reproduction of mammals. Golden hamsters are seasonal breeding mammal and their sexual activity is determined by photoperiod(length of light per day). Long photoperiod(LP, $\leq$ 12.5 hours of light) maintains the reproductive activity and short photoperiod(SP, $\leq$ 12 hours of light) suppresses it. In order to investigate in detail, the sexual activity was individually examined in SP-housed male golden hamsters received a vector at three different concentrations which contains rat GnRH cDNA. The gonadal regression was significantly(P<0.05) accelerated by the highest concentrations of the vector at 8 and 10 weeks after the treatment in comparison to the other groups. In the light of pulsatile release of GnRH in maintaining reproductive activity, the vector containing GnRH cDNA might secrete the GnRH in a constant high level. These results suggest that the GnRH-containing vector might desensitize the anterior pituitary, leading to acceleration or testicular regression.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.38 no.4
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• pp.232-238
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• 2005

This paper describes reproduction, population structure, growth and size at sexual maturity of a deep-water mud shrimp (Solenocera melantho) in the adjacent waters of Geomun Island, Korea. The shrimp was caught by a beam trawl from November 1998 to December 1999. Spawning period was estimated by gonadosomatic index to be from August to early November with a peak in October to early November. Female shrimps were $12\%$ matured at 16 mm in carapace length, $33\%$ matured at 18 mm and $75\%$ matured at 22 mm. The size at $50\%$ maturity for female was estimated to be 20.65 mm in carapace length. Breeding season was estimated to be from August to early November with a peak in October to early November. The size at $50\%$ inseminated was 19.81 mm CL. The fecundity was 87,500-405,200 and related exponentially to carapace length and total weight. This species survived between 25 and 26 months. The maximum carapace length of females and males were 48 mm and 34 mm respectively. Sex ratio was $51.3\%$, and the females were preponderant. Growth was estimated by modified von Bertalanffy growth function incorporating seasonal variation in growth in both years females (K=1.019/yr and $L_{\infty}$=51.731 mm CL) grew faster, reaching a larger size at a given age than males (K=1.848/yr, and $L_{\infty}$=27.499 mm CL). This is indicated by differences in growth performance indices $(\varphi')$ between females (3.291) and males (3.145).