• Korean Journal of Ichthyology
• /
• v.22 no.3
• /
• pp.195-200
• /
• 2010

A large volume of hatching jar was tested whether it is an effective to hatch fertilized eggs of Pacific cod. The volume of hatching jar did not show any significant differences in survival of the fertilized eggs; 48.3% for the jar of 15 L and 50.4% for that of 42 L. Survival rate of the fertilized eggs in a large volume of hatching jar ranged from 40.0 to 71.2%, which was higher than those of conventional small circular tank. A higher survival could be achieved even though stocking density of fertilized eggs was as high as 5,000 mL/jar. Consequently, the tested hatching jar allowed for incubation of a greater number of eggs with higher survival rate in a much smaller space. In addition, it reduces costs and manpower, and requires a relatively small amount of water per individual unit (6,700 mL/min), and provides a way to incubate multiple rearing groups in a quarantine environment.

• Korean Journal of Veterinary Research
• /
• v.33 no.2
• /
• pp.277-283
• /
• 1993

In the present study, observations were made on the life-history of Lymnaea viridis under laboratory conditions, involving incubation period of the eggs and their hatching rate, shell length of the newly hatched snails, sexual maturity, size of the snails when the snail produced the first egg-mass, the number of eggs in each egg-mass, egg-laying, ovipostion, growth rate of the snails, and longevity of the snail. At temperatures between $19.8^{\circ}C$ to $22.5^{\circ}C$, incubation period of the eggs occupied 10~12 days, and after beginning of hatching, all young snails emerged completely from the egg-mass within 5 days. The hatching rate was 88%. The average shell length of the newly hatched snails was about 0.064cm. The rate of growth was extraordinarily rapid under good laboratory conditions. When two snails were reared in one culture vessel($20{\times}15{\times}5cm$) with blue-green algae at about $22^{\circ}C$, snail growth was optimal, taking 37 days to reach 1.2cm in shell length. Sexual maturity reached in about 19 days. The size of the snails at sexual maturity was $0.78{\pm}0.05cm$ in length and $0.47{\pm}0.04cm$ in width. The first egg-masses produced were $0.59{\pm}0.22cm$ in length and $0.34{\pm}0.08cm$ in width, and contained 7~38 eggs. The eggs are usually laid in water. The egg-laying was affected by food and temperature. Snails fed with blue-green algae at about $22^{\circ}C$ produced larger egg-masses than the snails fed with fish food at about $26^{\circ}C$. Under conditions of continuous activity and growth, the maximum expectation of life appears to be 109~350(mean 230) days. And the shell length of snails at death were 1.39~1.64cm.

• Journal of Aquaculture
• /
• v.20 no.4
• /
• pp.239-247
• /
• 2007

We studied spawning, hatching and larval growth of Amphiprion melanopus under laboratory conditions. Each time a fish spawned about 440 to 650 eggs. The eggs were hatched 9 days later. Nest colour of the eggs changed from clear yellow orange to greyish violet with processing of embryogenesis. With regard to spawning according to the substrates, the fish prefered red clay pot and ceramic pot to volcanic scoria and live rock. Hatching rate (%) of the eggs on the former substrates was significantly higher than that on the latter. The number of eggs varied with the food stuff supplied to the fish. The fish fed Tetra bits (commercial diet), meat of short necked clams and mussels, and astaxanthin showed significantly higher fecundity with 638 eggs than that fed only Tetra bits (477 eggs) or Tetra bits with meat of shellfish without astaxanthin ($549{\sim}553\;eggs$). Higher temperature ranging from 24 to $30^{\circ}C$ induced shorter incubation period and smaller total length, but higher hatching rate. The optimum salinity and L:D cycle with $60\;{\mu}mol$ photon $m^{-2}s^{-1}$ for hatching were 33 psu and 16:8, respectively. The newly hatched larvae about 4.6 mm in total length grew to 7.5 mm in one week, 18.8 mm in a month and 37.9 mm in 70 days after hatching.

• Parasites, Hosts and Diseases
• /
• v.22 no.2
• /
• pp.171-180
• /
• 1984

In order to provide some clues for differential diagnosis of trematode infections in fecal examination, the comparative morphology of eggs of 5 kinds of heterophyid flukes (Metagonimus yokogawai, Heterophyes heterophyes nocens, Heterophyopsis continua, Stellantchasmus falcatus and Pygidiopsis summa) and Clonorchis sinensis was studied. The eggs were obtained from distal portion of uteri of worms which were recovered from men after treatment. The characteristic shape and appearance of each kind of eggs were observed in detail under light microscope, and their length and width measured and compared one another. The results are as follows: 1. Eggs of C. sinensis are elongated ovoidal in shape with attenuated anterior end, 25.3~33. 2 (28. 3 in average) ${\mu}m$ long and 14.2~17.4(5.9) ${\mu}m$ wide with length/width ratio of 1.60~2.00 (1.78). They differ from all heterophyid eggs in that they have prominent wrinkling (muskmelon pattern) at their shell surface. 2. P. summa eggs are ovoid to pyriform in shape and characterized by the smallest size of all kinds examined, 19.8~22.9 (21.6) ${\mu}m$ long and 11.1~13.4 (12.1) ${\mu}m$ wide and the ratio 1.63~1.99 (1.78). 3. Eggs of S. falcatus are elongated ovoidal and most slender form, 25.3~29.2 (27.2) ${\mu}m$ long and 11.1~13.4 (12.5) ${\mu}m$ wide with the ratio of 2.00~2.57 (2.17). 4. Eggs of M. yokogawai are ellipsoid to elliptical in shape with round both ends, 26.9~31.6 (28.5) ${\mu}m$ long and 14.2~18.2 (16.8)${\mu}m$ wide with the ratio of 1.48~2.11 (1.70). 5. H. continua eggs are oval in shape, sometimes similar to M. yokogawai or H. h. nocen$ eggs, however, the relative breadth is broadest among all kinds, with maximum width at posterior half portion. They are 23.7~27.7 (25.0) ${\mu}m$ long, 15.8~18.9 (16.4) ${\mu}m$ wide with the ratio of 1. 33~1.75 (1.53). 6. Eggs of H. h. nocens are ellipsoid to ovoid in shape but sometimes more slender than M. yokogawai and have slightly pointed both ends. They are 23.7~29.2 (25.7) p.m long, 14.2~15.8 (15.4) ${\mu}m$ wide, and the ratio 1.50~2.06 (1.67). From the results, it is concluded that eggs, of 5 kinds of heterophyids and C. sinensis can be morphologically differentiated one another, however, careful observation and measurement on sufficient number of eggs are needed.

• Korean journal of applied entomology
• /
• v.44 no.1 s.138
• /
• pp.61-65
• /
• 2005

Egg-forming and preservation methods for the indoor-rearing system of the emma field cricket, Teleogryllus emma, were investigated. The oviposition preference experiment on different mats, soil(natural oviposition mat) and $oasis^{\circledR}$(artificial oviposition mat), showed that T. emma preferred to oviposit on the $oasis^{\circledR}$. On the other hand, $oasis^{\circledR}$ had more inactive number of eggs laid per female and hatchability than another. However, the number of eggs laid per female and hatchability within 50 days after emergence were better than soil. The experiment on the hatching of the eggs showed that eggs could be stocked at $10^{\circ}C$ for 40 days with 14 day pre-period after laying, representing $62.1\%$ hatchability, when considering generation shortening. On the other hand, When it had been kept in cold storage for 90 days at $7.5^{\circ}C$ with 14 day pre-period after laying it, appeared to be the most suitable for long period-storage method by hatchability $65.1\%$.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.16 no.4
• /
• pp.389-394
• /
• 1983

The right eye flounders, Limanda yokohamae Gunther widely distributed in the coastal waters of Korea and Japan. On Feburuary 3, 1983, the authors obtained a number of artificial fertilized eggs from the adult fishes(male: 285mm in total length; female: 297mm) caught by a trawl. The eggs of this species is demersal and adhesive, and the diameter of these eggs was varied in $0.71{\sim}0.80mm$. The egg capsule is colorless and transparent, and the eggs do not contain any oil globules, The hatching took place in 120 hour after fertilization at the water temperature $5.5{\sim}17.0^{\circ}C$. The newly hatched larvae were $2.64{\sim}2.72mm$ in total length with long trunk. Myotome number was $9{\sim}10+30{\sim}32=39{sim}42$ and yellowish brown melanophores were appeared. In 3 days after hatching out. The larvae attained 3.3mm in total length, and the mouth began to move. Xanthophore appeared also on the opereulum at this time. After 7 days the larvae attained 3.70mm in total length, and became the postlarvae absorbing the yolk completely.

• Food Science of Animal Resources
• /
• v.32 no.2
• /
• pp.198-203
• /
• 2012

To improve hygienic quality of egg, the ozone treatment was applied. Eggs were inoculated with Salmonella Typhimurium, and the inoculated eggs were treated by ozone (38.8 ppm) for 10-30 min. Furthermore, microbiological and chemical quality changes of eggs were investigated during storage. Initial number of S. Typhimurium of egg shell was 6.18 log CFU/g and the number was increased during storage (p<0.05). However, those of ozonated samples for 10-30 min were 4.22-5.25 log CFU/g, which was lower than that of the control. Especially, ozone treatment for 30 min achieved about 2 decimal reductions and the numbers were maintained during storage. Other physical and chemical characteristics of eggs by ozone treatment, including Haugh unit, yolk color, pHs of egg white and yolk, foaming ability, foam stability and lipid oxidation development were not different when compared with that of the control. Therefore, ozone treatment is one of the available methods to improve hygienic quality of eggs.

• The Korean Journal of Pesticide Science
• /
• v.12 no.2
• /
• pp.155-161
• /
• 2008

The inhibitory effect of herbal extracts using methanol and hexane collected from Sudan and Korea was evaluated on egg hatching of Meloidogyne incognita. The concentration of herbal extracts were 10,000, 1,000 and 100 ppm, respectively. They were treated to Meloidogyne incognita eggs after 3, 7, and 21 days of hatching. All herbal extracts inhibited egg hatching significantly compared to the control. The degree of inhibition was directly related to the concentration of the extracts. At 10,000 ppm, very fewer individuals were hatched at all the periods of exposure with the exception of the extract of fruits of Quisqalis indica which gave 84.4 and 54.5% at 7 and 21 days, respectively. Egg hatching was completely ceased, especially after 7 days for most of the extracts. While at 1,000 ppm relatively high numbers of eggs were hatched compared to the higher concentration, as well the extracts Q. indica reported many number of hatched eggs compared to others, especially at 21 days. On the other hand, the extract from pods of Cucumis mello var agrestis gave the least hatching number of eggs at all periods of exposure which gave 2, 8, and 3% at 3, 7, and 21 days, respectively in comparison to the control. Whereas at 100 ppm, inhibition increased with exposure time. However, the extract leaf of Desmodium caudatum represented the fewer hatching eggs at 3 and 7 days.

• Korean journal of applied entomology
• /
• v.39 no.1
• /
• pp.53-58
• /
• 2000

The effect of NeemAzal-T/S was tested by leaf disk method on fecundity, egg mortality, and preference of twospotted spider mite, Tetranychus urticae and its predator mite, Amblyseius womersleyi in the laboratory. Mortalities of T. urticae and A. womersleyi adults were 97.7% and 20.0%, in 100ppm treatment at 72 h after application, respectively. The mean number of eggs laid per T. urticae female adult were 0.0 and 18.5, and those of A. womersleyi were 1.6 and 2.9 at 100 ppm and 0 ppm concentrations, respectively. Hatchability of T. urticae eggs treated with 50 and 100 ppm were 52.8%, and 2.5%, respectively, and those of A. womersleyi eggs were 100% and 91.3%, respectively. Choice and no-choice tests revealed that T. urticae female preferred to alight and oviposit on untreated bean leaf disk with 13.8 to 18.2 eggs per female. In contrast, A. womersleyi female preferred on treated or untreated bean leaf equally. There was no significant differences in the number of consumption of T. urticae eggs by A. womersleyi on treated and untreated bean leaves, except 200 ppm. These results indicate that NeemAzal-TIS is highly toxic to T. urticae, and is less toxic to A. womersleyi. It may be concluded with these results that NeemAzal-T/S could be incorporated into integrated T. urticae management system.

• Korean journal of applied entomology
• /
• v.44 no.2
• /
• pp.157-159
• /
• 2005

The number of winter buds oviposited by Drycosmus kuriphilus against chestnut varieties was lower of Ishizuchi and Daap than that of Okkwang, Tsukuba and Arima. D. kuriphilus oviposited multiful eggs in each winter bud of most of the chestnut varieties tested. More than three eggs were oviposited on winter bud of lower shoot of native, Tsukuba, Okkwang and Pyounggi varieties. However, average laid eggs less than one were on winter buds of Tshizuchi and Daap. Number of eggs oviposited in winter bud on lower shoot was higher than those on upper one. More than 15 eggs were oviposited in Tsukuba, whereas one or less egg was oviposited in Daap. Rates of winter buds oviposited by D. kuriphilus in native, Arima and Tsukuba were 83.8, 78.5, and $75.9\%$, respectively.