• Korean Journal of Fisheries and Aquatic Sciences
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• v.8 no.4
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• pp.234-241
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• 1975

Reproductive cycle of Haliotis discus hannai Ino was studied based on the samples which were collected in Yeosu area from January, 1973 to December, 1974. Particular emphasis was paid on the seasonal variation of gonad maturity factor, coefficieot of gonad maturity, fatnesss, and relationship of gonad weight to growth of the abalone. seasonal fluctuation of water temperature and induction of artificial spawnings were also checked. The abalone of this area spawns twice a year: spring spawning(early May-late July) and Autumn spawning(early September-late November). peak spawning occurs from late May to middle of June for spring spawning: it occurs from late September to early November for Autumn spawning. Gonad maturity factor was closely related to the spawning seasons. For the spring spawning Gonad maturity factor reached to its maximum value as 18.84 in April; for the Autumn spawning it reached to its maximum value as 22.65 in September. Annual minimum value was 12.65 in January. Annual maximum values of coefficient of gonad maturity were 44.10 in May and 49.05 in September and the annual minimum was 10.09 in January. Fatnesswas highest in July as 0.221 and it was lowest in October as 0.1058. Ratios of shell length to gonad weight were formulated as follows : $$In\;September\;GW=0.000003710SL^{3.7860}$$ $$In\;January\;GW=0.000021198SL^{2.8564}$$ $$Annual\;mean\;GW=0.00000005013SL^{4.2273}$$ Relations of total weight to gonad weight were formulated as follows : In September GW=0.1918TW-4.9231 In January GW=0.0992TW-0.1759 Annual maan GW=0.1568UW-3.5256.

• Korean journal of applied entomology
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• v.58 no.1
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• pp.69-76
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• 2019

This study was evaluated to increase the production efficiency of Gryllus bimaculatus De Geer, which are recently increasing attention as industrial insects in Korea. In this study, the hatching rate and larval period were investigated along with temperature and humidity, as well as the survival rate and ovipositional temperatures along with rearing density. The optimum relative humidity for hatching was highest at 90%, which shows the hatching rate of 90%. The highest hatching rate was 98.3% at $20^{\circ}C$. The hatching period was shortest at $35^{\circ}C$ incubation, which shows 7.1 days in average. The survival rate at 3,000-20,000 individuals in the breeding container was 34-18% after rearing for 35 days. In the effect test of feeding vegetables, the survival rate was 1.8 times and the biomass weight 2.5 times higher than that of normal individuals respectively. The number of laying eggs by temperature was highest at $25^{\circ}C$, which shows 1,710 eggs after reading for 30 days.

• Korean Journal of Environment and Ecology
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• v.36 no.6
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• pp.615-626
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• 2022

This study investigated the habitat characteristics and spawning ecology of Hippocampus haema (Syngnathidae) in Soando Island, Korea, from May 2015 to December 2016. The survey site where seahorses inhabit was mainly formed by seagrass of Zostera marina populations. Total density and biomass (Mean±SE) of Z. marina were the highest at 136±14.4 shoots/m² and 489.8g DW/m², respectively, in spring (May), while the total density was lowest at 93±7.0shoots/m²in autumn (October), and biomass was the lowest and at 122.3g DW/m² in winter (February). During the study period, 293 individuals were identified through a diving and kick net survey, and the total length of H. haema ranged from 10.1 to 87.0mm. Male individuals nurturing fertilized eggs or larvae appeared beginning in May and were collected until October in both 2015 and 2016. Juvenile individuals were captured beginning in July 2015 and June 2016. As a result of a comprehensive analysis of the spawning season characteristics, it was estimated that the spawning season of H. haema was from April to October. The number of fertilized egg or larvae inside the male brood pouch were 38.3±14.8 (20-76), and the number of fecundity identified from female were 47.2±8.6 (31-59). The male-to-female ratio of H. haema was 1:1.7, indicating the dominance of males.

• Korean journal of applied entomology
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• v.44 no.4 s.141
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• pp.277-282
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• 2005

This study was conducted to investigate morphological characteristics and effects of temperature on the development of Piezodorus hybneri on soybean. The unibanded stink bug, Piezodorus hybneri, is a serious insect pest in soybean fields giving damage to seeds in pod and leaves of soybean lowering both quality and yield. Eggs were spherical and laid in two raws on the leaves and pods of soybean plants. Body lengths of females and males were 9.8 mm and 8.7 mm, respectively. Egg hatch rates were better in higher temperature within the range of examined temperatures, which ranged in $81.2{sim}93.2%$. The development periods of eggs at the temperatures of 20, 25, 30 and $35^{\circ}C$ were 10.7, 5.0, 4.0, and 3.0 days, respectively. Mean developmental periods of 1st, 2nd, 3rd, 4th and 5th nymphs at $25^{\circ}C$ were 3.2, 3.4, 3.4, 3.3 and 5.9 days, respectively. Development threshold and effective accumulative temperature were $13.3^{\circ}C$ and 65.5 DD (day degree) for egg stage, $9.9^{\circ}C$ and 322.8 DD for nymph stage, $10.7^{\circ}C$ and 386.4 DD from egg to adult, respectively. Oviposition began from 10 days after emergence at $25^{\circ}C$, and the longevity of female and male were 52.5 and 38.2 days, respectively. Total number of eggs and egg masses laid by a female at $25^{\circ}C$ were 496 and 21.3, respectively, The longevity of adult female was shortened with increasing temperature, whereas the total numbers of eggs laid by a female were decreased.

• Korean Journal of Environmental Biology
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• v.38 no.4
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• pp.586-593
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• 2020

This study was conducted to investigate the biological characteristics of Phanuromyia ricaniae (Hemiptera: Platygastroidea), an egg parasitoid of Ricania sp. (Hemiptera: Ricaniidae) as a biological control agent to control Ricania sublimata. The developmental period of P. ricaniae was 3.8 days for eggs, 11.1 days for larvae, and 16.3 days for pupae at 25℃, and 3.4 days for eggs, 7.8 days for larvae, and 15.3 days for pupae at 30℃. Except for the larval stage, the developmental periods were not significantly different, but the egg-to-pupa period at 30℃ was significantly shorter than that at 25℃. P. ricaniae emerged at the photophase in 24 hours, but not at the scotophase. A higher emergence rate (34.5%) was seen from 10:00 to 12:00 after the lights were turned. The female-to-male ratio of P. ricaniae was 3:1. The longevity of P. ricaniae adults was 49.0 days for females and 44.0 days for males at 20℃, 27.6 days for females and 28.4 days for males at 25℃, and 18 days for females and 14.0 days for males at 30℃. Its longevity at a low temperature (20℃) was longer than that at higher temperatures (25 and 30℃). Adult females laid eggs during all days except from 00:00-02:00 (scotophase time). The ovipositional distribution rate was 26.1% from 20:00 to 22:00, which was the peak, and the next peak was 15.7% at 10:00 to 12:00. P. ricaniae showed arrhenotokous parthenogenesis in which unfertilized eggs develop into males. Therefore, the results suggest that P. ricaniae may be a biological control agent for R. sublimata.

• Korean Journal of Ichthyology
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• v.19 no.4
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• pp.306-317
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• 2007

Reproductive cycle with the gonad developmental phases, first sexual maturity, spawning frequency, sex ratio of the dusky mud hopper, Periophthalmus modestus were investigated by histological observations. Monthly variations of the gonadosomatic index (GSI) began to increase in May and reached a maximum in June when the gonad was getting mature during the period of higher ground (water) temperature-long day length. Changes in the GSI showed a negative correlation to the HSI, but coincided with the fatness index. The reproductive cycle can be classified into five successive stages: in female, early growing stage (April to May), late growing stage (April to May), mature stage (May to June), ripe and spent stage (June to August), and recovery and resting stage (August to March); in males, growing stage (April to May), mature stage (May to June), ripe and spent stage (June to August), and recovery and resting stage (August to March); According to the frequency distributions of egg diameters during the breeding season, Periophthalmus modestus is presumed to be a summer breeder, asynchronous group and polycyclic species to spawn 2 times or more during the spawning season. Total eggs and mature eggs in absolute fecundity and relative fecundity (per cm) increased with the increase of body length. Total eggs and mature eggs in absolute fecundity and relative fecundity (per g) did not increase with the increase of body weight. Percentages of first sexual maturity of females and males ranging from 5.1 to 5.5 cm in body length are over 50%, and 100% for fish over 7.1 cm in body length. The sex ratios of females to males over 5.1 cm in body length were not significantly different from a 1 : 1 sex ratio.

• Development and Reproduction
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• v.9 no.2
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• pp.95-103
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• 2005

Reproductive cycle, gonadosomatic index(GSI), egg diameter composition, first sexual maturity, sexually matured length(50% of first sexual maturity), and sex ratio of Amusium japonicum japonicum, were investigated by histological observations and morphometric data. Samples were collected monthly from the subtidal zone of Sogwipo, Jejudo, Korea, for two years. The sun and moon scallop Amusium japonicum japonicum is dioecious. Monthly variation in the GSI showed similar patterns with the reproductive cycle. Ripe oocytes were about $70{\sim}90\;{\mu}m$ in diameter and had thick egg membranes. The spawning period was from November to January, and the main spawning occurred between November and December when the seawater temperature was relatively low. From monthly changes in egg diameter composition, the spawning period was once a year, although the number of spawning frequencies is assumed to occur more than twice during the spawning season. The reproductive cycle of this species could be divided into five successive stages: early active stage(April to June), late active stage(June to September), ripe stage(October to November), spawning stage(November to January), and spent/resting stage(February to April). First sexual maturities in female and male scallops ranging from 85.1 to 90.0mm in shell length were over 50% and they were 100% for scallops over 90.0mm in shell length. In this population, sexually matured shell lengths(50% of rate of group maturity) in females and males were 86.96 and 86.59mm, respectively. The female to male sex ratio among individuals over 85.1mm in shell length was not significantly different from 1:1($X^2=0.18$, p>0.05). No evidence of hermaphrodite was found in histological sections of any scallop examined.

• Korean Journal of Environment and Ecology
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• v.33 no.6
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• pp.677-685
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• 2019

We investigated the ecological characteristics of kumgang fat minnow (Rhynchocypris kumgangensis) in the Eocheon stream from October 2017 to September 2018. The water temperature was 10.2- 14.3℃ and remained below 15℃ during the year. The fishes in cohabitation with kumgang fat minnow were Cottus koreanus (16.62%), Phoxinus phoxinus (10.74%), Rhynchocypris oxycephalus (1.55%), Oncorhynchus mykiss (0.56%), Zacco koreanus (0.28%), and Iksookimia koreensis (0.14%%). The ratio of females to males was 1:0.91 and did not vary widely. The frequency analysis of total length indicated that the fishes with less than 40 mm in total length were one year old, those with 40 - 69 mm were two years old, those with 70 - 84 mm were three years old, and those with 85 mm or more were four years old for individuals collected in May through June. The sexually mature fishes were over two years old. The spawning season was from late May to late August, and the water temperature was 12.5~14.5℃ during the period. The prosperous spawning season was from June to July, and the water temperature was 13.6 - 14.5℃ during the spawning period. The average number of eggs in the ovaries was 1,006 (664 - 1,666) per matured female, and the matured eggs were yellowish and spherical with a mean diameter of 1.34±0.17 mm. The length-weight correlation of R. kumgangensis was BW = 0.00003TL^2.77 with the constant a as 0.00003, b as 2.77, the average condition factor (K) as 1.04(0.65~1.48), and the slope as -0.0012. The kumgang fat minnows inhabiting in the spring water had a longer spawning period, a fewer number of eggs in ovaries, and the lower condition factor (K) than those inhabiting other areas.

• Korean journal of applied entomology
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• v.38 no.1
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• pp.23-28
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• 1999

This study was conducted to determine the effect of temperatures, 24"C, 28$^{\circ}$C and 32"C,and food sources on pupal development, adult longevity and oviposition of tobacco cutworm, Spodopteralitura Fabricius. Percent pupation of S. litura was became higher at higher temperature from 23% to 88%.And its percent pupation was highest on soybean leaf (SL), followed by perilla leaf (PL), sweet potato leaf(SPL) and artificial diet (AD). Pupal weight ranged from 0.28g on SPL to 0.40 g on PL and was tended toheavier with decreasing temperature. The mean pupal duration was 14, 10 and 7 days at 24"C, 28$^{\circ}$C and32"C, respectively. Percent emergence was in range of 21% to 89% with higher percent emergence as thetemperature increased and both 28$^{\circ}$C and 24$^{\circ}$C was highest on SL, followed by PL, SPL and AD, but at24$^{\circ}$C the order was SPL, PL, SL and then AD. Preoviposition duration was 3.2 days at 24"C, 2.8 days at28$^{\circ}$C and 2.5 days at 32$^{\circ}$C. Adult longevity became shorter as the temperature increased from 6.4 to 3.9days. Male longevity was longer than that of female. Adults lived longest when they were reared on PL,followed by SL, SPL and AD. Total number of eggs laid per female varied from 803 to 1,441 regardlessof the treatments, but those were significantly more on natural foods than on AD. Number of eggs per eggmass was 97.4 at 24$^{\circ}$C 155.8 at 28$^{\circ}$C and 104.7 at 32$^{\circ}$C. Number of egg mass was 12.0, 6.7 and 11.3 at24"C, 28$^{\circ}$C and 32"C, respectively.4"C, 28$^{\circ}$C and 32"C, respectively.

• Korean Journal of Poultry Science
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• v.37 no.2
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• pp.181-190
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• 2010

Mycoplasma gallisepticum (MG) infection results in severe economic loss in the poultry industry. In the previous reports, F strain, one of the MG live vaccine strains, could protect the bird from field infection of MG strains. In this study, efficacy of PoulShot$^{(R)}$ MG-F vaccine againset mycoplasma gallisepticum infection was evaluated for filed application in commercial layers. Commercial layers from two different farms received with PoulShot$^{(R)}$ MG-F, MG-F live vaccine at 9~14 weeks of age. Serological immune response to MG vaccine, the persistency of MG vaccine strain in the upper respiratory tracts and egg production rate were evaluated in the vaccinated, contacted or nonvaccinated flocks. The serological response was first detected at 3 weeks after vaccination (WAV) and persisted for 31 WAV. The MG vaccine strains were also persisted for 31 WAV based on the reisolation and PCR detection. There was no difference between the vaccinated or non-vaccinated flocks in the egg production rate but in the abnormality rate of eggs. Based on the above results, we suggested that the PoulShot$^{(R)}$, MG-F live vaccine was fully immunogenic and had characteristics of long persistence in the upper respiratory trachea which will reduce economic loss caused by MG infection in the layer farms.