• Korean journal of applied entomology
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• v.50 no.4
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• pp.283-288
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• 2011

Occurrence of Scrobipalpa salinella (Zeller) was investigated on glasswort in Shinan, Jeonnam and Kimjae, Jeonbuk from 2010 to 2011. The occurrence of S. salinella observed four times in a year. Adult stages of S. salinella in two areas occurred from mid-April to late September. The peak times of 1st, 2nd and 3rd generation adults of S. salinella was observed on early May, mid-June, late July (in Kimjae) to early August (in Shinan) and early September, respectively. And larval stages of S. salinella occurred from late May to late August. The peak times of development of 1st, 2nd and 3rd generation larvae of S. salinella was observed on mid-June, mid-July and mid-August, respectively. However, the 4th generation larvae began to occur in mid-September but didn't damage in glasswort. Among the distances from the bank of glasswort field (3, 6, 9 m) and periods of damage (Jun. 16, Jul. 7, Aug. 12), larval density in 3 m distance from the bank in 1st damage season (Jun. 16) was high which resulted to severe damage. Damage of 2nd and 3rd generation larvae was progressed both density of larvae and levels of damage.

• Korean Journal of Agricultural and Forest Meteorology
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• v.25 no.1
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• pp.37-47
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• 2023

The black cutworm, Agrotis ipsilon (Hufnagel), is an important crop pest worldwide that feeds more than 80 plant species including cabbage, potato, maize, wheat and bean, and this moth is a typical pest attacking underground parts of crops. It has been known in farm booklets that the larvae of A. ipsilon overwinter in the soil in Korea, but no definitive data exist yet. This study was conducted to evaluate that the specific appearance time of A. ipsilon observed actually in the field could be explained when we assumed that this pest overwinters in a form of larvae or pupae. Degree day-based phenology models were applied for tracking forward or backward to find the predicted developmental stage which developed at a specific stage found in the field. As a result of the analysis, it was confirmed that an initial population could be established in a group that does not overwinter as larvae or pupae in Korea. In other words, the appearance of adults in early March to April could not be explained by the presence of domestic overwintering populations. Populations that overwinter as larvae or pupae in Korea were able to emerge as adults in June to July at the earliest. Therefore, the group of adults appearing in early spring is highly likely to be a population that migrated from outside Korea. Taken together, it was estimated that the colony of A. ipsilon in Korea would be formed by a mixture of a migrant population through long-distance migration and a overwintering population.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.28 no.5
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• pp.667-676
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• 1995

Settlement, recruitment, growth and production of Mactra venerifomis were investigated at Kunsan tidal flat located in the west coast of Korea from lune 1993 to May 1994. High density of planktonic larvae of M. veneriformis was observed between the mid and early July in 1993. The size of the newly settled larvae ranged from 250 to 350um in shell length with mean density of 601$inds.\cdot m^{-3}$. Recruitment of M. veneriformis larvae was occurred mainly in the mid June to mid July 1993. The larvae have no substratum preference during the larval settlement phase. Mortality of larval was affected by environment (substratum, exposure time, density of adult clams). After settlement they grew until November, and stopped growing in winter from December. The estimated turnover rate of M. veneriformis larvae was estimated as high as 4.91 and 4.94. Annual production of the 0-age group was estimated to be 2,900g $m^{-2}\;\cdot\;yr^{-l}$, which was relatively high compared with those of other age groups.

• Korean journal of applied entomology
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• v.48 no.2
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• pp.269-274
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• 2009

Rearing media were selected for the production of sterile larvae of greenbottle blowfly, Phaenicia (=Lucilia) sericata (Meigen) which is widely used in maggot therapy. Eight media available in the market were used in this study. Egg hatchability was not different among the media. Survivorship of the larvae was higher in blood agar (BA), sabouraud dextrose agar, and brucella blood agar than the others. A higher content (20${\sim}$40%) of sheep blood in BA and chocolate agar increased the survivorship of larvae. The eggs and the early 3rd larvae could be stored for 12 days at $8^{\circ}C$ and for 15 days at $6^{\circ}C$ without decrease in hatchability and larval survivorship, respectively.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.51 no.5
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• pp.549-555
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• 2018

The objectives of this study were to confirm the nutritional requirements and improve the survival of the walleye pollock Theragra chalcogramma, a cold seawater fish, by enrichment. We analyzed the fatty acids and amino acids of fertilized pollock eggs before hatching, just-hatched larvae, larvae that had absorbed only the yolk sac, and larvae starved for 2 days after yolk absorption. For the survival improvement experiment, we administered docosahexaenoic acid (DHA), eicosapentaenoic acid (EPA), and DHA-EPA enrichment. Fatty acid decreased DHA and EPA content. On the $30^{th}$ day, body growth was significantly greater in pollock given the EPA and DHA-EPA treatments (P<0.05). Larval survival at 20 and 30 days after hatching (DAH) was greatest under the DHA-EPA treatment (P<0.05). Survival was significantly lower under the EPA treatment at 10 DAH, but then increased to approach that seen under the EPA-DHA treatment (P<0.05). Therefore, we determined that reduced survival in hatchlings of high-mortality pollack could be improved by controlling EPA and DHA content during enrichment. We conclude that cold seawater fish must be given feed that meets their nutritional needs, which can be accomplished using newly manufactured enrichment products for the larvae of cold seawater fish, such as pollock.

• Korean journal of applied entomology
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• v.27 no.4
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• pp.194-199
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• 1988

The seasonal movements of Holotrichia morosa and H. diomphalia in soil were investigated during the period from 1984 to 1986 in Suwon. Most cf the eggs, active larvae and adults of the two species could be found at the soil depth of I-IDem. The larvae began downward movement in late October and early November in order for overwintering when soil tempe¬rature at 5cm below ground reached about $10^{\circ}C$. The overwintering depths of the larvae were 10-40cm for H. morosa and 30-80cm for H. diomPhalia. After the overwintering, pupation and adult emergence of H. morosa occurred at the overwintered sites, \vhereas H. diomPhalia larvae returned to near soil surface next April, and resumed feeding. H.diomphalia larvae began to move downward again in late June for pupation and adult emergence, and overwintered thereafter as adults at the depth of 1O-40cm.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.16 no.4
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• pp.395-400
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• 1983

Rock trout, Agrammus agrammus(Temminck et Schlegel) is commonly found at the coast of Korean waters. Mature adult of the rock trout were collected at the shore of Dongbaeksom in Pusan during the period from Nov. 18 to Nov. 25, 1983 through know the early developmental characters. The authors carried out the artificial insemination in the laboratory on Nov. 24, 1982, and roared the eggs and the hatched larvae. The eggs of this species are demersal and adhesive, and their diameter were varied within 1.92-2.14mm. The color of yolk is light blue in the early developmental stage, and then turned to orange before hatching out. The yolk contained numerous tiny oil globules. Hatchig toot plnace in ca. 463 hours after insemination at $11.8-17.9^{\circ}C$ of water temperature. The newly hatched larvae were elongate in share and 6.55-8.20 mm in total length with 12+26=48 myomers. Many branched melanophores were distributed on the supra-orbital, dorsal double body contour, and peritoneal, and also under the notochord of the tail.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.21 no.3
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• pp.139-144
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• 1988

The vertical distribution of eggs and larvae of anchovy. Engraulis japonica were studied based on ichthyoplankton and the temperature distribution in the southwestern part of the Sea of Japan off Korea during the summer of 1985 and 1986. Thermoclines occurred at the surface layer in the coastal area and at the sub-surface layer in the offshore area in the early summer of 1985. However, they occurred at the surface layer throughout the summer of 1986. Anchovy eggs and larvae were abundant in the offshore in 1985 and in the coastal area in 1986. It seems that the spawning ground of anchovy in 1985 shifted to the offshore owing to the sloping of thermoclines. According to the distribution layer of anchovy eggs by developmental stage, the eggs in the early developmental stage were abundant at $0\~30m$ layer about 06:00. But the eggs in the late developmental stage were abundant at $30\~100m$ loom layer about 24 : 00. These results suggest that anchovy spawn at the $0\~30m$ layer at night and eggs tend to sink to the $30\~100m$ layer in the course of development.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.53 no.1
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• pp.83-89
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• 2020

This study provides a detailed morphological description of larvae obtained from Urocampus nanus and Syngnathus schlegeli male brood fish over 20 days of culture in the laboratory. In both species, mating takes place when several males each spread their brood pouch like a wing to attract a female's attention. When the female begins to swim upward, the males follow her and receive her eggs in their brood pouches. Newborn larvae of U. nanus and S. schlegeli had already completed formation of dorsal and caudal fin rays, but not of pectoral fin rays. Pectoral fin rays were completely formed 15 days after release in S. schlegeli and 20 days after release in U. nanus. The ratio of caudal fin length to standard length increased until 8 days and decreased thereafter in S. schlegeli, while in U. nanus this ratio declined continuously after hatching. The larvae of the two species were very similar in external morphology, but well distinguished by the number of dorsal fin rays (15-16 in U. nanus vs. 39-43 in S. schlegeli), the presence of a membrane under the tail (absent in U. nanus vs. present in S. schlegeli), and the presence of melanophores in the dorsal fin (present in U. nanus vs. absent in S. schlegeli). Based on this study, U. nanus appears to be evolutionally more similar to pipefish than to seahorse.

• The Korean Journal of Zoology
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• v.32 no.1
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• pp.1-8
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• 1989

Non-diapausing larvae and diapausing pupae of Pieris rapae L. were treated with 20-HE and JH, and the concentration of 20-HE and JH in body were also measured to determine mechanisms of diapause induction and termination. When early last instar larvae of non-diapausing stage were injected with 20-HE or JH-I, diapause was not induced in both cases. 20-HE concentration of pre-diapausing last instar larvae was very low, and 20-HE peak of non-diapausing two-day-old pupae was not present in diapausing pupae. There was no difference in concentration of JH-I between diapausing and non-diapausing stages. When early and late diapausing pupae were injected with 20-HE, JH-I, or JH-III. diapause was terminated by 0.1-0.5 $\mu$g of 20-HE, but not by JH-I, or JH-III. The above results indicate that diapause of Pieris rapae was induced by decrease of 20-HE concentration and also terminated by gradual accumulation of 20-HE during diapause process.