• Korean journal of applied entomology
• /
• v.61 no.1
• /
• pp.101-108
• /
• 2022

Because of their specificity to target insects and relatively low toxicity to non-target organisms, insect growth regulators (IGRs) have been regarded as attractive alternatives to chemical insecticides. Commercially available IGRs are classified into juvenile hormone agonists (JHAs), ecdysone agonists (EAs), and chitin synthesis inhibitors (CSIs) according to their mode of action. Recently, JH-mediated interaction of methoprene-tolerant (Met), which is JH receptor, and its binding partners have been replicated in vitro using yeast cells transformed with the Met and FISC/CYC genes of A. aegypti. Using this in vitro yeast two-hybrid β-galactosidase assay, juvenile hormone antagonists (JHANs) have been identified from various sources including chemical libraries, plants, and microorganisms. As juvenile hormone (JH) is an insect specific hormone and regulates development, reproduction, diapause and other physiological processes, JHANs fatally disrupt the endocrine signals, which result in abnormal development and larval death. These results suggested that JHANs could be efficiently applied as IGR insecticides with a broad insecticidal spectrum. This review discuses JH signaling pathway mediated by Met and future prospects of JHANs as environmentally benign IGR insecticides.

• Proceedings of the Korean Aquaculture Society Conference
• /
• 2003.10a
• /
• pp.74-75
• /
• 2003

This study was conducted to investigate the effects of several additives(macroalgae, wasabi, and herb) in formulated diets on the growth, body composition, blood chemistry and non-specific immune response of juvenile flounder. Three replicates of juveniles (average weight 8.4 g) in flow-through aquarium system were fed one of six isonitrogenous (45%) and isolipidic (8%) diets containing 5 and 10% Undaria powder, 2% wasabi leaf, 2% wasabi stem, and 0.5% herb (Obosan) for 8 weeks. Survival was not affected by the different dietary additives (P>0.05). The highest weight gain and feed efficiency offish fed the diet containing 0.5% herb were significantly higher than those of fish fed the diets containing 10% Undaria powder (P<0.05). No significant differences were found in contents of moisture, crude protein, lipid and ash of whole body (P>0.05). Fish fed the diet containing 10% Undaria powder showed the highest moisture and the lowest crude lipid contents in the liver. Although hematological parameters (red blood cell, hematocrit and hemoglobin) and serum constituents (glucose, total cholesterol and glutamic-oxaloacetic transaminase) contents of fish varied between treatments, no specific trend was observed throughout feeding periods. Lysozyme activity in the serum and nitroblue tetrazolium reduction of macrophage in the head kidney from fish fed the diets containing herb was significantly higher than those of fish fed the control diet. The results of this study suggest that herb as an additive in this formulated diet may improve growth and non-specific immune response of juvenile flounder.

• Journal of Aquaculture
• /
• v.9 no.3
• /
• pp.233-237
• /
• 1996

A growth study was conducted to investigate the effect of stocking density on performance of juvenile fat cod (Hexagrammos otakii Jordan et Starks.). Fish averaging 13 g were stocked into duplicate tanks ($250\;{\ell}$ each) at four different densities of 330 g/$100\;{\ell},\;660\;g/100\;{\ell},\;990\;g/\;100\;{\ell}$, and $1330\;g/100\;{\ell}$, and fed MP diet containing $50\%$ frozen horse mackerel and $50\%$ commercial binder meal for 2 months. Weight gain, feed efficiency, survival rate, and protein retention were decreased as density increased. Whereas these parameters were not significantly different (P>0.01) fish stocked at initial stocking densities of $330\;g/100\;{\ell},\;660\;/g/100\;{\ell}\;and\;990\;g/100\;{\ell}$. Moisture and lipid content of whole body were not affected by stocking densities (P>0.01). These results indicate that stocking density should be considered, and $1{\~}2$ kg fish/$100\;{\ell}$ final stocking density for juvenile fat cod could be used to decrease production cost for the indoor tank (culture) system.

• Fisheries and Aquatic Sciences
• /
• v.12 no.4
• /
• pp.350-353
• /
• 2009

As a result of human industrial development, carbon dioxide ($CO_2$) is currently accumulating in the atmosphere and dissolving into the oceans. Sequestration into the deep sea has been proposed as a possible solution to this increasing atmospheric $CO_2$, although the impact of such a program on marine ecosystems is unknown. We examined the effects of increased $CO_2$ levels on the growth of the olive flounder, Paralichthys olivaceus. Juvenile olive flounder 40 days post hatching were exposed to two levels of $CO_2$ (3.60-7.55 and 4.05-11.46 kPa) in running seawater for 26 days. During the exposure period, the pH and $CO_2$ levels of the water were measured, and the numbers of dead individuals were counted in each aquarium. Following the exposure period, the total lengths (mm) and body weights (mg) of the juvenile fish were measured. Both $CO_2$ treatments significantly increased fish mortality compared to controls ($19.87\pm4.53%$ vs. 7.14% and $75.96\pm1.36%$ vs. 7.14% for high and low doses, respectively). After the high $CO_2$ treatment, total length ($14.98\pm6.58$ mm vs. $19.52\pm1.83$ mm) and body weight ($28.92\pm13.85$ mg vs. $67.35\pm18.32$ mg) of the exposed flounder were reduced compared to the control fish; however, no significant differences in these values were observed after the low $CO_2$ dose. These results suggested that $CO_2$ exposure inhibits growth in the juvenile stage and that $CO_2$-enriched seawater is toxic in the early life stages of olive flounder.

• Fisheries and Aquatic Sciences
• /
• v.8 no.3
• /
• pp.128-131
• /
• 2005

The effects of alternate-week feeding strategies on growth and feed efficiency ratio of juvenile Nile tilapia were investigated in a recirculating aquaculture system. Twenty fish initially weighing 25.5 g were randomly distributed into each of 18 tanks to conduct three replicates for each of six different feeding strategies. Weight gain of fish in the control that were fed daily for 6-week feeding trial was significantly higher than those of fish subjected to various alternate-week feeding regimes. Weight gain of fish that were starved for 3 weeks and then fed daily for 3 weeks (3WS+3WF) was not significantly different from that of fish, starved and fed daily for alternate 1-week period during the trial (1WS+1WF), but was significantly higher than those of fish starved for 2 weeks, and fed for 2 weeks (2WS+2WF); fish starved for 4 weeks and fed for 2 weeks (4WS+2WF); and fish fed for 5 weeks and fed for 1 week (5WS+1WF.) The amount of feed supplied to fish in the groups of 1WS+1WF and 3WS+3WF was significantly lower than that fed to fish in the control group, but significantly higher than the amount feed supplied to fish in the other three groups. Feed efficiency ratio for fish in the control group did not differ from that for fish in the groups of 1WS+1WF, 2WS+2WF and 3WS+3WF, but was significantly higher than that for fish in the groups of 4WS+2WF and 5WS+1WF. In conclusion, juvenile Nile tilapia that were subject to starvation for 1 to 5 weeks did not exhibit compensatory growth sufficient to attain the same weight as fish fed daily for 6 weeks. In addition, fish subjected to starvation exhibited low feed efficiency ratio compared to fish fed daily, which were probably attributable to poor weight gain.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.49 no.6
• /
• pp.823-829
• /
• 2016

Yacon (YC), ginger (GG) and blueberry (BB) were added to the diet of juvenile rockfish Sebastes schlegeli to investigate the effects of these substances on growth, feed utilization and resistance to Streptococcus iniae compared to feed additive ethoxyquin. A total of 480 fish were distributed in 12 tanks and four experimental diets [control (Con), with 0.01% ethoxyquin, and 1% YC, GG and BB diets] were provided in triplicate. After an 8-week feeding trial, 20 fish from each tank were infected with Streptococcus iniae. Fish fed the BB diet had higher weight gain than fish fed the GG and Con diets. Feed efficiency of fish fed the GG and YC diets was higher than that of fish fed the BB and Con diets. The protein efficiency ratio of fish fed the GG diet was higher than that of fish fed any other diet. The cumulative mortality 54 h after infection of fish fed the Con diet was higher than that of fish fed any other diet. These results indicate that YC, GG, and BB are effective dietary additive, not only improving growth performance and feed utilization but also lowering the mortality of juvenile rockfish exposed to S. iniae.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.52 no.5
• /
• pp.474-481
• /
• 2019

This study evaluated the chronic effects of $NO_3-N$ on juvenile blackhead seabream Acanthopagrus schlegelii. The experiment used six identically configured recirculating aquaculture systems (435 L), with three tanks (70 L) each. The $NO_3-N$ concentrations studied were 0 (control), 62.5, 125, 250, 500, and 1,000 mg/L $NO_3-N/L$. Thirty juvenile blackhead seabream ($18.8{\pm}2.2g$) were stocked in each tank. Growth and hematological changes were evaluated after 120 days. At the end of the experiment, the growth, survival, and cortisol levels indicated that blackhead seabream were healthy in 500 mg $NO_3-N/L$. However, insulin-like growth factor I (IGF-1) and the IGF-1 receptor were significantly lower at 250, 500, and 1,000 mg $NO_3-N/L$ than in controls (62.5 and 125 mg $NO_3-N/L$). Juveniles were likely affected at a much lower $NO_3-N$ concentration than 250 mg/L $NO_3-N/L$ in terms of IGF-1 and the IGF-1 receptor. Therefore, for the sake of long-term fish welfare, the $NO_3-N$ should be maintained at lower than 250 mg/L for blackhead seabream in recirculating aquaculture systems.

• Journal of Nutrition and Health
• /
• v.39 no.4
• /
• pp.392-402
• /
• 2006

The purpose of this study was to compare the eating habit, food intake frequency and preferred food and taste of juvenile delinquents (100 numbers) and male high school students (100 numbers), using questionnaires from August to October 2004. 1) It was shown that the juvenile delinquents took more unbalanced diet (p<0.05), smoking (p<0.001) and drinking (p<0.001) than general students, while general students had more eating between meals (p<0.01). 2) The intake of food was a significant difference in white rices (p<0.01), bibimbab (p<0.001), kimbab (p<0.001), fried rice (p<0.001), ramen (p<0.001), jajangmyun (p<0.001), jambong (p<0.001), hamburger (p<0.001), pizza (p<0.001) and breads (p<0.05). The juvenile delinquents took more major food than that of general students in all the items except for white rice. It was observed, then, that the juvenile delinquents showed more intake of such subsidiary foods as bulgoki (p<0.001), roasted thin pork chops (p<0.001), grilled pork belly (p<0.001), pork cutlet (p<0.01), sweet and sour pork (p<0.001), chicken with ginseng (p<0.001), fried chicken (p<0.001), kimchi pot stew (p<0.01) and zucchini (p<0.05) than general students, with general students taking more kimchi (p<0.01) and fried or boiled soybean curd (p<0.01). The intake of dessert was a significant difference in yogurt (p<0.01), orange juice (p<0.001), cola (p<0.001), soft drinks (p<0.001), ion drinks (p<0.001), coffee (p<0.001), apple (p<0.01), banana (p<0.001), orange (p<0.001), cake (p<0.001), hot dog (p<0.001), ddokbokgi (p<0.01), mandu (p<0.001), fried fish paste (p<0.05), steamed korean sausage (p<0.001), fried foods (p<0.05), hem & sausage (p<0.001), cheese (p<0.001), ice-cream (p<0.001), candy (p<0.01), chocolate (p<0.001), mayonnaise (p<0.05), jam (p<0.01) and butter & margarine (p<0.01). Then, the juvenile delinquents were shown to entirely have more intake of all the desserts than those of general students. 3) Regarding preference of foods, it was shown that the juvenile delinquents preferred cereals (p<0.05), grilled pork belly (p<0.001), chicken with ginseng (p<0.01), anchovies and small fish (p<0.05), chicken with ginseng (p<0.05), seasoned spinach (p<0.001), seasoned zucchini (p<0.001), milk (p<0.05), coffee (p<0.001) and butter & margarine (p<0.05) while general students did egg (p<0.01), soybean sprout soup (p<0.001), boiled or fried potato (p<0.05), seasoned soybean sprout (p<0.05), boiled or fried soybean curd (p<0.01), fried foods (p<0.01) and snack (p<0.05). For their preference of tastes, hot taste (p<0.01) was higher in the juvenile delinquents. 4) Under general environments there was a change of the difference in their behaviour of pork cutlet (p<0.01) intake in accordance with other family and of milk (p<0.001) and butter & margarine (p<0.05) preference in accordance with growth in a big city between the two groups.

• The Korean Journal of Malacology
• /
• v.30 no.4
• /
• pp.303-309
• /
• 2014

The development of Japanese geoduck, Panopea japonica, grown under culture conditions, has been examined through the morphological characteristics in fertilized egg, larvae and juvenile. Gametes were stripped from ripe broodstock and placed into two separate containers. Eggs were washed through a $40{\mu}m$ sieve and fertilized with dilute sperm solution. Developing larvae were maintained at $19{\pm}1^{\circ}C$. Fertilized eggs with $81.6{\mu}m$ diameter developed to trochophores within 14 h and to D-stage larvae ($116{\mu}m$ shell length) within 27 h. Larvae were spontaneously settled at shell length of $311{\mu}m$ after 20 days. The hatching from fertilized eggs and larval rearing were normally available in $18.5-21.5^{\circ}C$, and the growth was good in a cashmilon substrate, as well as sand. After rearing of day 108 from metamorphosis, the shell length of juvenile P. japonica reached 13 mm, and growth rate of shell length of the juvenile was $117.5{\mu}m/d$.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.34 no.5
• /
• pp.570-575
• /
• 2001

Three feeding experiments were conducted to investigate the effects of herbs (Obosan-C or Obosan-O) as an additive in formulated diets on growth and body composition of juvenile abalone (Haliotis discus hannai), Three replicate groups of abalone initially average weighing 206 mg, 827 mg and 432 mg were fed the each one of experimental diet containing $0\%\;or\;1\%$ Obosan for 10 (experiment 1), 7 (experiment 2) and 19 weeks (experiment 3), respectively. In addition, an imported commercial diet for abalone was also employed to compare growth performance of juvenile abalone. Weight gain of abalone fed the diet containing Obosan-O was significantly (P<0.05) higher than that of abalone fed the control diet in the experiment 3. Moisture, crude protein and ash contents of soft whole body were not influenced by dietary herbs (P>0.05), whereas crude lipid content of abalone fed the diets containing Obosan-C was significantly (P<0.05) lower than that of abalone fed the control diet in the experiment 2. The results indicate that Obosan-O as an additive in formulated diet can improve body growth of juvenile abalone.