• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.3 no.3
• /
• pp.187-198
• /
• 1970

The author succeeded in rearing the young blue crab from the first stage of zoe ato the true crab shape, and during this time he observed their growth and metamorphosis. The relationships between the number of eggs carried by female crabs (E) and the carapace width (C) and body weight (W) are shown as follows: E= 27.9049C-281.8155, E=0.5682 W-116.4606. There are five zoeal stages and a megalopa in the complete larval development of the blue crab. Water temperature in rearing aquaria ranged from 21.4 to $25.2^{\circ}C$. The duration of each zoeal stage was two days on the average. After the fifth moulting, the zoea becomes megalopa and 5 to 6 days later the megalopa moults and develops into the first stage of adult crab shape. The carapace width of megalopa measured about 1.70 mm and the carapace length, from the tip of the rostrum to the posterior dorsal margin of the carapace, was about 2.78 mm on the average. The carapace width and length of the first crab, 18 days after hatching, measured about 4.48 mm and 2.62 mm respectively. After two days, the first crab moulted and grew into the second crab with about 6.47 mm in carapace width and 4.66 mm in carapace length. The larval rearing in the outdoor tank shelved better results than in the indoor aquarium. The highest mortality occurred when the first stage of zoea moulted into the second stage. Percentage of crabs which survived, from the first crab to the ninth crab stages, was about $55\%$. The relationships between rearing days (D) and the carapace width (C), carapace length (L) and body weight (W) of the crab stages during 40 days of rearing are shown as follows. Carapace width, Indoor: C=1.1250D+1.7227 Outdoor C=1.3465D -0.2449 Carapace length, Indoor: L=0.6654D+1.6712 Outdoor: L=0.7893D+0.6919 Body Weight, Outdoor: $$W=1.15e^{0.12423D}$$ Indoor: $$W=6.759\times10^{-2}D^{1.2598}$$ (9-19 day old crabs) Outdoor: $$W=4.136\times10^{-2}D^{1.6024}$$ (21-40 day old crabs) During the crab stage, the following relationships between the number of moulting times and the carapace width (C), carapace length (L) and body weight (W) were found as follows: $$C=5.2e^{0.28119N}$$ $$L=3.65e^{0.26372N}$$ $$W= 0.14e^{0.7037N}$$ The relationships between the carapace length (L) and the carapace width (C) and body weight (W) of the crab stages are shown as follows: Carapace length, mm Formula 2.62-27.17 L=1.6864C-1.0387 7.47-18.53 $$W=9.367\times10^{-5}C^{3.5567}$$ 22.11-27.17 $$W=3.406\times10^{-5}C{3.8571}$$

• Korean journal of applied entomology
• /
• v.12 no.1
• /
• pp.41-46
• /
• 1973

1) The optimum temperature for mass rearing of stable fly was $26^{\circ}C$ centigrade. Number of days required for stage of development at $26^{\circ}C$ were 6.8 days for larval stage, 5.3 days for pupla stage, 10.4 days for preovipositionla stage, and 30 days for adult stage respectively. 3) The pupation rate, emergence rate and sex ratio were $80.7\%,\;84.3\%$ and 1 : 1, respectively. 3) The average weight of pupae was 14.5mg, and the standard medium showed better result in larvae rearing than wheat bran medium. 4) The optimum number of eggs for inoculation on 125gr medium was approximately 310. 5) Optimum size of resting place was determined as $2inch^2/adult$ when it reared in a rectangular cage.

• Journal of Sericultural and Entomological Science
• /
• v.9
• /
• pp.43-47
• /
• 1969

This experiment was carried out to investigate the effect of gamma ray on the eggs of later stage in late fall rearing season. The results are summarized as follows: 1. The duration of larval stage was simmilar to that of control in any dose. The silkworm growth was uniform in does of 4,000 gamma ray, but in does of 8,000r 16000r was irregular. There were not malformed silkworms but many small silkworm. 2. Mortality of silkworms was very high 8,000r and over; virus diseases of 87.6 per cent, flacherie of 5.9 per cent and complication of 6.5 per cent. 3. The more the dose of gamma ray became, the lighter the weight full grown silkworm and matured silkworm became. 4. The uniformness of cocoons was registered in dose of 2,000r and the cocoons were irregular or small in dose of 16,000r

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.37 no.1
• /
• pp.7-12
• /
• 2004

This study investigated the possibility of salinity acclimation of freshwater rotifers (Brachionus calyciflorus) as live food for sweetfish (Plecoglossus altivelis) larvae, and also examined the optimal salinity for the growth of sweetfish. Freshwater rotifers cultured in 0 and 4 PSU and seawater rotifers (B. rotundiformis) cultured in 33 PSU were supplied to the larvae with four kinds of enrichment material (condensed freshwater Chlorella, $\omega-yeast,$ baker's yeast, Super Selco) and larval growth at 4 PSU was examined. Growth of the freshwater rotifers positively increased from 0 PSU to 6 PSU, but decreased when over 8 PSU was reached. Growth and survival of the sweet fish larvae reared in 0 PSU were significantly lower than those reared in either 4 PSU or 33 PSU. This indicated that the freshwater rotifers (B. calyciflorus) could be used as live food for sweetfish larvae reared in 4 PSU. The body weight of sweetfish larvae fed on freshwater rotifers enriched with Super Selco was the highest at 0.163 mg, but there was no significant difference in survival and body length of the fish fed with the other enrichment materials. The content of n-3 HUFA of the sweetfish larvae fed on the freshwater rotifers enriched with Super Selco and the condensed freshwater Chlorella was higher than that enriched with $\omega-yeast$ and baker's yeast. These results indicated that B. calyciflorus cultured with the condensed freshwater Chlorella could be used for the sweetfish larvae without enrichment, and the most efficient enrichment material for B. calyciflorus is Super Selco.

• Fisheries and Aquatic Sciences
• /
• v.8 no.1
• /
• pp.27-33
• /
• 2005

This is a subsequent study to our previous finding that Pacific oysters, Crassostrea gigas, gained a so-called upper plateau concentration, around 30,000 ng/g dry weight digestive gland for benzo(a)pyrene, showed reproductive behavior but produced their ensuing reproductive outputs damaged. A serial dilution of sediment elutriates from Jinhae Bay, Korea, where pollution was progressive, were exposed to gametes of the Pacific oyster for 0, 5, 10, 20, 30, and 60 min to detail the pollutant effects on very young specimens. There was an apparent critical dilution over which adverse effects are evident. This was $10\%$ of the present sediment elutriate, corresponding to 0.3 ng/g on the basis of total polycyclic aromatic hydrocarbons (PAHs) for the oyster. Within the dilution the embryonic development was not influenced by the duration of exposure to its gamete stage. At higher dilutions over the critical dilution, occurrence of abnormality increased dependent on the pollutant dilution and the duration of exposure. Similar trends were also found in larval mortality. However, overall, the chemical toxicity was more significant to morphogenesis than to survival, suggesting a potential recruitment of the pollutants-induced abnormal larvae in the wild population to threaten the population integrity.

• Fisheries and Aquatic Sciences
• /
• v.7 no.4
• /
• pp.192-203
• /
• 2004

The effects of temperatures, starvation, and kind of foods on growth, RNA/DNA ratio and protein contents during metamorphosis and early juvenile stage of olive flounder (Paralichthys olivaceus) were examined. During metamorphosis, warm-acclimated fish showed higher RNA and DNA content than those of the cold-acclimated fish, excepting H stage (28 DAH) at which the ratio was higher at cold temperature. RNA/DNA ratio during metamorphosis showed similar values at two temperatures tested. However, after 42 DAH warm-acclimated juveniles had higher DNA content compared with cold-acclimated fish, resulted in marked decreases in RNA/DNA ratios. Higher RNA content at H stage of cold-acclimated fish was consistent with an increase in protein content. Growth of fish rearing at warm temperature was higher than those of fish at cold temperature during all experiments. In starvation experiment, contents of DNA, RNA and protein significantly decreased. Even though there were no significant differences in total length (TL) and body weight between the live mysid-fed and artificial pellet-fed fish at 35 mm TL, both RNA/DNA and protein/DNA ratios of the former group was significantly higher than those of the latter due primarily to lower DNA content of the live mysid-fed group. The results from this study suggest that temperature, starvation and kind of foods should be considered when RNA/DNA ratio applied to assessing the cultured larval and juvenile fish condition.

• Journal of Sericultural and Entomological Science
• /
• v.24 no.2
• /
• pp.73-80
• /
• 1983

1. The varietal difference in amylase activity of the digestive fluid of the 5th instar larvae reared on the artificial diet was investigated, using the parent commercial silkworm varieties of Japanese strain. The amylase activity was large different among silkworm varieties. The activity was strong in Hansaeng-1, Jam 115 and Jam 117, medium in Hansaeng-3, Jam 113, Jam 119, and Jam 201, weak in Jam 107, Jam 121 and Gyeongchu. The amylase of the digestive fluid of ten parent commercial silkworm varieties is possible-(ae) type, compared with ＋(＋$\^$ae/) type of Daizo. 2. To investigate the effect of a-amylase pre-treatment of the artificial diet, larvae were fed with the diet treated by a-amylase during 4th-5th instar periods. The blood sugar content and cocoon qualities were slightly higher in the experimental larvae than those in the control, while showing the slight less body weight, amylase activity and dietary efficient.

• Journal of Apiculture
• /
• v.33 no.4
• /
• pp.261-268
• /
• 2018

Queen honey bees (Apis cerana) can be reared artificially on demand by the use of grafting technique. The technique consists of grafting young worker larvae into queen cell cups and raising in a queenless strong colony. As the age of grafted larvae for queen rearing exhibited several aspects related to quality and reproductive potential of queen, this study were conducted to investigate the influence of age of grafted larva on morphological characteristics and lifespan of queen, and the growth of colony she headed. Our results demonstrated that queens reared from young worker larvae (i.e., less than 1-day old larvae) were significantly larger in size (i.e., body weight and thorax width) than that of queens reared from 2-day old worker larvae. Moreover, queens reared from younger worker larvae initiated egg-laying earlier, stored more spermatozoa in spermatheca and had a longer lifespan compared to queens raised from older worker larvae. We also found a significant positive effect of queen grafting age on the production of worker and drone brood, adult worker population in colonies headed by queens reared from younger larvae. These findings suggested that rearing queens from brood grafted at the earliest possible age could increase the reproductive potential of queen as well as fitness of colony she head.

• International Journal of Industrial Entomology and Biomaterials
• /
• v.37 no.2
• /
• pp.69-72
• /
• 2018

A new silkworm variety 'Chilseongjam' was bred for special purpose as educational learning and festivals. Their breeding history and major characteristics are as follows. The Chilseongjam variety was selected and succeeded from the F1 of Galwon ${\times}$ C721 in 2009 autumn. They are showing 94% (spring & autumn) of high practical hatching ratio. The larval period of Chilseongjam (spring: 23 d, autumn: 24 d 3 h) was shorter than that of Daebakjam (spring: 24 d, autumn: 25 d 23 h). In the pupation percentage, Chilseongjam (spring: 96.6%, autumn: 86.1%) is similar to Daebakjam Daebakjam (spring: 96.3%) in spring, but autumn is lower than Daebakjam (autumn: 94.9%). Single cocoon weight (spring: 1.57 g, autumn: 1.29 g) and Cocoon yield (spring: 14.2 kg, autumn: 11.1 kg) were lower than those of Daebakjam (spring: 2.76 g, 25.4 kg, autumn: 2.19g, 20.2 kg), respectively. The new silkworm variety, Chilseongjam showed higher pupation rate than control variety. This variety can be used as a educational learning and festivals.

• International Journal of Industrial Entomology and Biomaterials
• /
• v.37 no.2
• /
• pp.73-81
• /
• 2018

The giant mealworm beetle, Zophobas atratus (Coleoptera: Tenebrionidae), is a tropical beetle. As this beetle can be used as an ingredient in animal feed, the effects of brewer's spent grain (BSG) on the development and nutritional value of Z. atratus were investigated. As results, there were no significant differences on the larval survival rate, body weight, and duration at different content of BSG, mixed with conventional feed, wheat bran (WB). Based on these results, BSG can be mixed with wheat bran as a Z. atratus food ingredient without any problems. The nutritional value was compared between 100% wheat bran control and 50% BSG experimental groups. The moisture, crude protein, carbohydrates, and amino acids were 1.1-1.4 times higher in the 50% BSG group. In the BSG group, the linoleic acid content was 1.6 times higher than that in the control group. In the wheat bran group, the oleic acid content was 38.4%, which was 1.3 times higher than that in the BSG group. As minerals, the control and BSG groups showed high potassium and phosphorus contents. In terms of hazardous materials, four heavy metals (lead, mercury, arsenic, and cadmium) and two microorganisms (Escherichia coli and Salmonella spp.) were not detected. There were no significant differences in developmental characteristics between the wheat bran and BSG mixed groups, and the nutritional values were better in the BSG mixed group. Therefore, BSG can be used as alternative food source for rearing Z. atratus.