• Korean Journal of Fisheries and Aquatic Sciences
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• v.35 no.6
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• pp.551-556
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• 2002

We have experimentally evaluated the content of thyroid hormones (THs), the growth and activity of larval rockfish (Sebastes schiegeli) born from parturient mother fish injected with 20 $\mu$g/g BW of 3,5,3-triiodo-L-thyronine ($T_{3}$). There was no difference of L-thyroxine ($T_{4}$) levels between controls (sham control and control) and $T_{3}$ groups in yolk-sac larvae just born from broodstock, while $T_{3}$level of $T_{3}$ group was significantly increased compared with controls. In addition, the both larval $T_{3}$ and $T_{4}$ levels in $T_{3}$ group were always higher than those of control during experimental period. Also, there were significant differences in the development of larvae from the two groups. The larval growth in total length and body weight according to the elapsed days after parturition showed the linear and curve equations, respectively, and the slopes of $T_{3}$ group were significantly higher than those of control. The survival rate of larvae in $T_{3}$ group was higher than that of control. Although the survival rate in $T_{3}$ group under the condition of starvation was significantly depressed compared with the control, larval swimming index in $T_{3}$ group was higher than control. Finally, these findings suggest that the exogenous $T_{3}$ could be transferred into hatched larvae in parturient rockfish by maternal injection, and subsequently the exogenous hormone could play some roles on physiological metabolism of larvae after parturition and may confer a distinct advantage to the fragile larvae during the early developmental stage.

• Journal of Aquaculture
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• v.15 no.1
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• pp.23-29
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• 2002

To develop techniques for the production of artificial seedling of Corbicula japonica, protocols for induction of spawning and larval development were developed. During the assumed spawning period of August to mid-September, attempts were first made to induce spawning by gonadal incision and UV-irradiation but all in vain. At the end of August, elevated thermal induction evoked 90 % positive response in animals maintained at $3\textperthousand$ salinity. Immersion in (1/1000~3/1000 N) ammonium hydroxide ($NH_4$OH) also induced spawning in 15~45%) of the treated animals at $3\textperthousand$ salinity. Fertilized eggs measured 86$\mum. At 23.0~24.5$^{\circ}C$, the fertilized egos developed into 4-cell stage embryos within 2 hours, trochophores 15 hours, D-shaped larvae 2 days, umbo 9 days and fully grown veligers, ready to infiltrate into the sediment, within 16 days.

• Development and Reproduction
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• v.8 no.1
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• pp.11-17
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• 2004

The larvae and juvenile development of haddock Melanogrammus aeglefinus which is significant commercial fish living north Atlantic Ocean are described here. Larvae were reared in laboratory and sampled periodically for developmental study until 67 days after hatching. An increase in total length(TL) of fish indicated continuous growth, described by the growth expression Y=4.07 $e^{0.037}$( $R^{2}$=0.9978). The newly hatched pre-larvae was 4.9 mm in TL with ellipsoid yolk. In 16 days after hatching, larvae attained 6.8 mm in TL, and absorbed the yolk completely to become post-larval stage, but first heterotrophic food could be in 7 days after hatching already. Post-larval stage continued during 16~52 days after hatching with development of organs attachment. In 61 days after hatching with 41.3 mm in TL, the fries became a juvenile stage respectively having small teed lateral line, and a black blotch on the flank same as adults, but chin barbel was not developed yet. It was presumed that haddock changed food and ecological behavior after metamorphosis ken this time.e.

• Korean journal of applied entomology
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• v.32 no.2
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• pp.236-244
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• 1993

The development of OrientaL tobacco budworm (OTE), Heticoverpa assulta, was studied at seven constant temperatures from 18 to $33^{\circ}C$ with a 14L : 10D photoperiod on the artificial diet. The egg, larval, and pupal duration comprised ca. 10, 48, and 42% of the total developmental time (from egg to adult emergence). The lower developmental threshold temperatures for egg, larval, pupal, and overall development were 8.62, 12.65, 11.64, and $11.89^{\circ}C$, respectively. The biophysical model of Sharpe & DeMichele (1977) provided a good description of OTB's development as a function of temperature ($r^2$=0.993~O.996). The Wmbull distribution was fitted to cumulative frequency distributions of normalized developmental times for each developmental stage of OTE ($r^2$== 0.987 ~0.999).

• Korean Journal of Veterinary Research
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• v.39 no.3
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• pp.602-608
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• 1999

Two-day old house fly adults were exposed to six insect growth regulators, flufenoxuron, teflubenzuron, triflumuron, diflubenzuron, methoxyfenozide, tebufenozide, as a feed additive (milk+5% sugar+chemical) in the laboratory for 6 days. The number of eggs deposited by the exposed-adults, viability of the eggs, and $F_1$ larval development were checked. All the IGRs tested were found to have no adverse effect on the reproduction of house fly, except methoxyfenozide (210ppm). The most effective inhibitor to egg hatch was flufenoxuron, followed by teflubenzuron, triflumuron, and diflubenzuron. Exposure to flufenoxuron (over 5ppm), teflubenzuron (over 25ppm), triflumuron (over 125ppm), and diflubenzuron (over 125ppm) reduced egg hatchability to 0 to 1.3%, but lower concentrations of these IGRs were less effective (6.3 to 46.3% egg hatchability). Almost all the larvae emerged from eggs deposited by the adults exposed to diflubenzuron (62.5ppm) and teflubenzuron (12.5ppm) failed to develop into pupae, causing total mortalities of 98% and 100%, respectively. However, two IGRs, methoxyfenozide and tebufenozide, did not inhibit egg hatch and $F_1$ larval development, except methoxyfenozide (210ppm) treatment These results suggest that these 4 IGRs may be used in the development of autosterilization system for house fly control. However, further work is required to develop delivery systems capable of transferring an effective dose to the fly under field conditions.

• Journal of Aquaculture
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• v.16 no.4
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• pp.240-244
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• 2003

The primitive gonad development in Paralichthys olivaceus was classified into (ⅰ) primordial germ cell (PGC), (ⅱ) genital ridge type (GRT), (ⅲ) primitive gonad type I (PGT I) and (ⅳ) primitive gonad type II stages. In the control group, PGC was recognizable on the 3rd days after hatching, and the primodial gonad after 24th days, while it was around the 22nd day after hatching in the group exposed to PCBs 3.0 $\mu\textrm{g}$/L for 30 days. Likewise, the progress of kidney development was recognized in four stages; unitubular type of mesonephric duct (UTMD), the branched mesonephric duct (BMD), convoluted tubule formation (CTF) and glomerulus appearing (GA) stage. It was structurally completed between the 25th and 30th day after hatching in two groups. There was no significant difference (p>0.05) in the time scale of development of gonad, and kidney between control and the PCBs - exposed group.

• Fisheries and Aquatic Sciences
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• v.21 no.12
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• pp.37.1-37.10
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• 2018

The larvae and juveniles of Porocottus leptosomus belonging to the family Cottidae were collected (n = 95, 3.9-16.5 mm in body length, BL) from Busan, Korea, in March 2015. The larvae and juvenile were identified using DNA barcoding as P. leptosomus, and their morphological description was presented in detail. The yolk-sac larvae (3.9-5.6 mm BL) body was slightly compressed, the head was large, the eye was round and large, and the anus was before the middle of the body. The preflexion larvae (5.2-10.0 mm BL) body length drastically increased; caudal fin rays began to occur. The flexion larvae (9.4-11.8 mm BL) notochord flexion started; dorsal, pectoral, and anal fin rays began to occur; pelvic fin buds are seen; they possessed a pair of parietal spine; and a pair of supraocular cirri was first to develop. At 12 mm BL, the notochord was completely flexed. The larva stage (3.9-12.6 mm SL) had the stellate melanophores in the head, isthmus, gut, and tail (along to the ventral midline). During the juvenile stage (11.4-16.5 mm BL), melanophores covered the head and began to form five black bands on the side of the body. The larvae of P. leptosomus spent pelagic life, but moved to the bottom during the juvenile stage. The larvae and juveniles of P. leptosomus differ from other cottid larval fishes by body shape, melanophore head pattern, and spine development. P. leptosomus can be distinguished from Porocottus allisi by morphological development and the occurrence of larval fish: preopercular spine development, melanophore pattern, and caudal fin development.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.27 no.4
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• pp.380-389
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• 1994

Larvae of the freshwater shrimp, Macrobrachium nipponense(De Haan) were reared in the laboratory under constant conditions ($25^{\circ}C,\;7\%0$ S), and their feeding rate, oxygen consumption, ammonia nitrogen excretion, and growth were measured at regular intervals during development from hatching to post larval stage. Growth was measured as dry weight, carbon, nitrogen, hydrogen, protein and lipid. All these physiological and biochemical traits revealed significant changes from instar to instar. Average feeding rate was high in intermolt stage of the molt cycle and it showed a bell-shaped pattern. Respiration(R) increased from hatching to post larval stage. Excretion(U) increased in intermolt phase of larvae and it showed a bell-shaped variation pattern, in all larval instars with a maximum near the middle of the molt cycle. Regression equations describing rates of feeding, growth, respiration and ammonia excretion as functions of time during individual larval molt cycles were inserted in a simulation model, in order to analyse time-dependent patterns of variation as well as in bioenergetic efficiencies. Carbon was initially increased and nitrogen showed a tendency to increase in premolt phase during individual molt cycles. Protein remained clearly the predominant biochemical constituent in larval biomass.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.8 no.4
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• pp.225-233
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• 1975

Morphological changes of early post-larval and young stages of Chasmichthys dolichognathus HILGEnDORF (Family Gobiidae) have been studied based on the samples of 953 individuals collected in June 1968, July 1969 and July 1971. Particular emphasis was paid on the development of fin rays, chromatophore patterns and ventral fins. The primordial fin rays of the first dorsal fin appear in the post-larvae of around 8.0 mm in total length, and dorsal fin fully develops in the larvae of around 9.2 mm. In the early young stages of 17.0 mm in total length fin rays have completely developed. According to chromatophore patterns the larvae are grouped into three successive groups. The larvae at the early stages of 6.3-14.2 mm have melanophores on the whole dorsal surface, the posterior ventro-lateral part of the tail and the basal part of the caudal fin. In the later larval stages of 17.0-24.4 mm a group of melanophores are added on medio-lateral part of the tail. These melanophores extend anteriorly and eventually cover the medio-lateral part of the whole body. In the early young stages of 97.2-34.8 mm the chromatophores cover the whole body surface in cloudy and H-shaped patterns. The chromatophore patterns of this stage are distinctive as generic characters of the fish. Fin membranes of the ventral fin appear in the post-larval stage (ca. 7.4 mm), and the primordial fin rays develop in the late post-larval stages (ca. 14.2 mm). The fin rays develop into a complete sucker in the young fish stage of around 30.0 mm in total length.

• Korean journal of applied entomology
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• v.51 no.4
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• pp.383-388
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• 2012

This study was conducted to assess damage to the welsh onion by Acrolepiopsis sapporensis Mastumura (Lepidoptera: Acrolepiidae) during the summer season, and to estimate the economic injury level (EIL) which results, providing basic data for pest management. The adult peaks of A. sapporensis in Suwon were observed in March, April, May, and September of 2009 and 2010 through the use of pheromone traps. The feeding of A. sapporensis results in white lines on the surface, and holes within welsh onions. During the entire larval period, one larva was able to damage 1.6 leaves and punch 11.9 holes, resulting in a total damaged leaf area of $1,321.6mm^2$. Through cage experiments and larval releases, a reduction of the mean number of leaves, increased percentage of leaf damage, and reduction in gross weight and marketable weight were observed. We could obtain a regression equation that showed a clear positive correlation between pest density and percentage of damaged leaf. Using this equation, the EIL of A. sapporensis on welsh onion was calculated to one larva per 10 plants based on 7% leaf damage observed for welsh onion.