• The Korean Journal of Ecology
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• v.23 no.1
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• pp.65-70
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• 2000

Field collections were made from six gypsy moth (Lymantria dispar L.) Populations in Kyonggy and Cheju areas during the period 1987∼1997. Characteristics of gypsy moth populations at different phases were examined in terms of egg mass density, relative larval density, plant damage, and fecundity. Males captured in pheromone trap were recorded, and we examined if there was a relationship between numbers captured and the population density during the following generation. Egg mass density was closely related with larval density, and furthermore these densities were correlated with the level of plant damage, indicating that larval dispersion was limited in oviposition areas. The gypsy moth population cycle was short in Korea with the period from population development to innocuous level usually lasting 2∼3 years. Male caught by pheromone trap (mean number of males caught per trap per day in peak emergence period) was positively correlated with egg mass densities in the following season (r²=0.93). A low fecundity was detected from outbreak populations which accompanied defoliation. Fecundity of gypsy moth ranged from 538 to 601 at other phases.

• International Journal of Industrial Entomology and Biomaterials
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• v.21 no.2
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• pp.180-183
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• 2010

This study was performed to investigate the temperature-dependent development, longevity and oviposition of an indigenous larval parasitoid, Meteorus pulchricornis, on tobacco cutworm, Spodoptera litura. M. pulchricornis were reared at nine constant temperatures between 15 and $35^{\circ}C$. The developmental times of each three developmental stage decreased from 38.7 to 16.3 d between 15 and $30^{\circ}C$. However, M. pulchricornis showed longer developmental time at $32.5^{\circ}C$ (9.5, 7.7 and 17.2 days for each three developmental stage) than at $30^{\circ}C$ (8.9, 7.3 and 16.3 days for each three developmental stage). Immature M. pulchricornis could not develop any more at $35^{\circ}C$. The lower developmental threshold estimated by linear regression equation for the egg to cocoon, cocoon to adult emergence and egg to adult emergence were 5.1, 4.6 and $4.5^{\circ}C$. The thermal constant for each of the three stages were 217.2, 176.2 and 403.8 degree-days, respectively. When no food or 50% honey solution as a food source is provided for M. pulchricornis, the parasitoid survived for 8.3 and 55.9 days at $25^{\circ}C$, respectively. M. pulchricornis females laid 5.2 eggs daily and total of 131.6 eggs at $25^{\circ}C$ until it died. Peak age-specific fecundity was observed on $14^{th}$ day (9.6 cocoons) after parasitoid emergence and gradually decreased thereafter.

• Korean Journal of Ichthyology
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• v.6 no.2
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• pp.222-236
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• 1994

Sexual maturation and spawning of the spottybelly greenling, Hexagrammos agrammus were histologically studied under photomicroscopy by considering changes in gonadosomatic index, hepatosomatic index and fatness, egg diameter composition, first sexual maturity and fecundity. The fish samples were collected monthly at the coastal area of Tongbaeksom, Pusan, Korea from July 1991 to July 1992. The gonadosomatic index(GSI) increased in September and reached the maximum value(female 4.31, male 1.61) in November when the gonad was mature and ripe. The values were decreased suddenly during the spawning season from December, and declined from January to August. The annual variations of hepatosomatic index(HSI) appeared to be correlated with those of GSI in female but were not significantly correlated in male. HSI in female began to increase in autumn with the increase of GSI, and reached the maximum in winter when the ovary was mature. Percentages of first sexual maturity in female and male fish were 50 % in 11.0~11.9 cm and 100 % in 13.0~13.9 cm groups. Both sexes participated in reproduction from one year old. H. agrammus was considered as a polycyclic species and spawns 3 times or more in the spawning season. Number of total and mature eggs in the absolute fecundity were proportional to standard length and body weight, respectively. Number of total and mature eggs in relative fecundity were also proportional to standard length, but rather decrease with increasing of body weight. Fatness coefficients reached the maximum value(female 15.32, male 15.14) in September(growing stage), and the values were sharply decreased after spawning. Thereafter, fatness values were gradually increased, therefore, the monthly changes in fatness coefficient closely correlated with the reproductive cycle. Sex ratios of female and male sexes of this species are showed 54.18 %, 45.82 %, respectively.

• Korean Journal of Ichthyology
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• v.19 no.3
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• pp.179-184
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• 2007

Maturity and spawning of spinyhead sculpin, Dasycottus setiger were investigated using samples collected by the eastern sea danish seine and gillnet in the East Sea of Korea from January to December 2004. We analyzed monthly changes in maturity stages, gonadosomatic index (GSI), egg diameter, fecundity, total length at 50% group maturity, and sex ratio. GSI began to increase in August, reached a maximum between September and November, and decreased in December. The spawning period was August to December, and the main spawning period was September to November. The fecundity ranged from 6,210 eggs at 22.3 cm (TL) to 15,898 eggs at 32.2 cm (TL). The relationship between total length (TL) and fecundity (F) was $F=25.475TL^{1.818}$ ($R^2=0.761$), and F increased with TL. The TL at 50% group maturity was estimated to be 23.4 cm. The sex ratio was 1 : 1.3 (female : male), indicating the male population was seem to be slightly predominant.

• Journal of Aquaculture
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• v.21 no.1
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• pp.41-46
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• 2008

The purpose of the study was to suggest the optimal lipid enrichment conditions used digestive enzyme activity of rotifer changing due to water temperature and salinity. The high population growth appeared at the experiment temperature more than 28 degrees highly on the culture temperature(maximum 32 degrees, 1,453 individual/mL). The fecundity was low at high temperature, and the egg ratio was high at low temperature. Population growth of 10 and 15 ppt appeared in most highly, but the fecundity and the egg ratio were high most significantly appeared in natural seawater(32 psu). The digestive enzyme activity by the culture environment mainly showed high activity in natural seawater(amylase exclusion, 15 psu). However, the TAP activity by the water temperature showed highly at the more high temperature, but the amylase and the lipase appeared at low temperature. We carried out the lipid enrichment at 20 degrees and 26 degrees in a condition of the natural seawater. Total protein, the total essential amino acids differed not significantly. The methionine content that was essential amino acids, a total lipid content, unsaturated index of fatty acids, DHA and the DHA/EPA ratio were high significantly each in $20^{\circ}C$ enrichment trial. Therefore, we could suggest the $20^{\circ}C$ and natural seawater for the optimal lipid enrichment condition in aquaculture, because methionine contents, several indexes by the lipid, TG-lipase activity, fecundity and egg ratio are high.

• Korean journal of applied entomology
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• v.61 no.4
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• pp.563-575
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• 2022

Maruca vitrata is one of important pests in leguminous crops, especially red bean. We investigated the effects of temperature on development of each life stage, adult longevity and fecundity of M. vitrata for understanding the biological characteristics of the insect species at eight constant temperatures of 13, 16, 19, 22, 25, 28, 31, and 34℃. Eggs hatched successfully at all temperature subjected and larvae successfully developed to the adult stage from 16℃ to 31℃. The developmental period of egg decreased up to 31℃ and after then increased. The developmental period of larva and pupa, and adult longevity of M. vitrata decreased with increasing temperature. Lower and higher threshold temperature (TL and TH) were calculated by the Lobry-Rosso-Flandrois (LRF) and Sharpe-Schoolfield-Ikemoto (SSI) models. The lower developmental threshold (LDT) and thermal constant (K) from egg hatching to adult emergence of M. vitrata were estimated by linear regression as 12.8℃ and 280.8DD, respectively. TL and TH from egg hatching to adult emergence using SSI model were 14.2℃ and 31.9℃. Thermal windows, i.e., the range in temperature between the minimum and maximum rate of development, of M. vitrata was 17.7℃. In addition, we constructed the oviposition models of adult, using the investigated adult traits including survival, longevity, oviposition period and fecundity. Temperature-dependent development models and adult oviposition models will be helpful to understand the population dynamics of M vitrata and to establish the strategy of integrated pest management in legume crops.

• Proceedings of the Korean Society of Fisheries Technology Conference
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• 2002.10a
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• pp.220-221
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• 2002

The planktonic shrimp, Acetes chinensis Hansen, 1919 inhabits the coastal areas of the Info-West Pacific, Korea, China, Taiwan, and Japan and is most abundant along the coastal areas of Yellow Sea. Several studies have locally examined aspects of reproductive biology of the species such as reproductive cycle, spawning, maturity, breeding pattern and fecundity. (omitted)

• Korean journal of applied entomology
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• v.34 no.1
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• pp.1-8
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• 1995

The relationships between aphids, plants, other organisms and some physical components of the environment are reviewed. Aspects considered include year cycles, polymorphism fecundity, relationship of different groups of aphids with particular groups of plants, honeydew, alarm pheromones, aposematic colouring, camouflage, colour variation within species, morphological variation within species, multivariate analysis and problems of its interpretation, parasitism, stridulating mechanisms, predators, coevolution of plants and aphids, plant galls, trapping aphids and the interpretation of trap catches, an curation of aphid collections. References are given to sources of information about aphids, with special reference to the Korean fauna.

• International Journal of Industrial Entomology and Biomaterials
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• v.15 no.1
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• pp.69-73
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• 2007

To establish the indoor-rearing system of the emma field cricket, Teleogryllus emma, the effects of temperature on development and reproduction of the emma cricket have been studied. The influence of temperature on developmental periods of emma field cricket was investigated under the eight temperatures of 15, 18, 21, 25, 27, 29, 31 and $35^{\circ}C$, under $60{\pm}5%$ R.H. and 16L:8D photoperiod. The developmental periods of T. emma nymphs had a range of 124.8 days to 44.4 days at the temperature of $21^{\circ}C$ and $35^{\circ}C$, respectively. At $15^{\circ}C$ and $18^{\circ}C$, however, all tested individuals died before emergence. The highest survival rate was 90% at $25^{\circ}C$, but there were no statistically significant differences among the temperatures. The adult weight increased with increasing temperatures although the weight at $35^{\circ}C$ was decreased. In addition, the influence of temperature on reproduction of emma field cricket was investigated under three temperatures $22^{\circ}C,\;25^{\circ}C\;and\;28^{\circ}C$, under $60{\pm}5%$ R.H. and 16L:8D photoperiod. The longevity of female/male adults were 65.8/79.2 days, 68.5/67.8 days, 46.8/57.4 days at the temperature $22^{\circ}C,\;25^{\circ}C\;and\;28^{\circ}C$, respectively. The preoviposition periods were 32.5 days at $22^{\circ}C,\;22.9^{\circ}C$ days at $25^{\circ}C$ and 22.1 days at $28^{\circ}C$. The highest average fecundity per female was 737.3 at $25^{\circ}C$.

• Korean Journal of Environmental Biology
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• v.33 no.4
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• pp.468-475
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• 2015

Nonylphenol is one of endocrine disruptors, as structurally stable, hydrophobic compounds exhibit high condensability and long-lasting in the natural environment. The purpose of this study was to determine the toxic effects of nonylphenol on Daphnia magna. In acute toxicity test, D. magna was exposed for 48 h at concentrations of 0, 10, 18, 32, 56 and $100{\mu}g\;L^{-1}$ nonylphenol. In chronic toxicity test, D. magna were exposed through water for 21 days at concentrations of 0, 1.0, 1.8, 3.2, 5.6 and $10{\mu}g\;L^{-1}$ nonylphenol. Acute toxicity was assessed on the basis of immobility, while chronic toxicity was assessed on the basis of fecundity. The acute toxicity test on nonylphenol was showed that the values of 24 h and 48 h $EC_{50}$ were $25.0{\mu}g\;L^{-1}$ and $13.7{\mu}g\;L^{-1}$, respectively. In chronic test, fecundity was reduced significantly at $5.6{\mu}g\;L^{-1}$ of nonylphenol. These results indicated that nonylphenol have some hazard for acute or chronic toxicity to freshwater invertebrate organism.