• Korean journal of applied entomology
• /
• v.43 no.2
• /
• pp.143-153
• /
• 2004

Non-spinning syndrome of Bombyx mori has been serious issue in sericulture industry near Kyungbuk area. This study was focused on the analysis of the mechanism and on screening candidate chemicals inducing the anti-metamorphosis of the silkworms. Rearing temperatures or initial body weight of the final instar larvae did not affect a normal larval to pupal metamorphosis of B. mori. However, pyriproxyfen (a juvenile hormone (JH) agonist) induced follicle patency significantly even at its 10$\^$-8/ M concentration and inhibited metamorphosis of B. mori in both developmental time and dose dependent manners. Pyriproxyfen induced JH esterase (JHE) activity and downregulated expression of JH binding protein of 5. mori. These results suggests that pyriproxyfen induced JHE activity as a JH agonist and that the elevated JHE activity degraded endogenous JH and resulted in JHBP gene expression. Based on the fact that the JH agonist induced follicle patency and inhibited metamorphosis of B. mori, follicle patency bioassay suggested that three commercial pesticides including simazine, molinate or alachlor were proved to give potent JH agonistic effect on B. mori. Further direct exposure experiments to these candidates are required to determine the chemicals responsible for the non-spinning syndrome of 8. mori.

• International Journal of Industrial Entomology and Biomaterials
• /
• v.18 no.2
• /
• pp.105-112
• /
• 2009

The greenhouse whitefly, Trialeurodes vaporariorum (Westwood) and the sweet potato whitefly, Bemisia tabaci (Gennadius) are serious insect pests that have a wide host range including cucumber, tomato, and pepper. In this study, we tested larvicidal efficacy of several on-the-market environment-friendly agricultural materials (EFAM) to select the effective products after the target pests were stabilized in indoor rearing condition. The developmental periods of two whiteflies are as follows: in the case of T. vaporariorum, egg duration is 9.6 days and nymph is 18.9 days, and in the case of B. tabaci, egg duration is 7.4 days and nymph is 15.2 days under $25^{\circ}C$ with relative humidity (RH) of $60{\pm}5%$ and a photoperiod of 16 L:8D. The total period of T. vaporariorum was 5 days longer than B. tabaci. Among 22 EFAMs six products showed more than 60% of insecticide efficacy against T. vaporariorum BTV B, BTV D, BTV G, BTV L, BTV M, and BTV S. On the other hand, seven EFAM products showed over 60% of insecticide efficacy against B. tabaci BTV D, BTV G, BTV K, BTV L, BTV M, BTV N, and BTV U. In the case of Spodptera litura previously, 16 EFAMs were tested against $2^{nd}$ instar S. litura, and six EFAMs were found to have more than 90% efficacy. Test of these six EFAMs against entire larval stages were performed in this study. Although some of these products showed still more than 90% of insecticidal efficacy against up to $3^{rd}$ instar larvae, the efficacy of these EFAMs sharply decreased as ages increase, resulting in less than 60% of efficacy of the products at most. This result indicates the difficulty to control S. litura with the on-the-market EFAMs alone under economic injury level. Collectively, it is required to find more EFAMs, and find alternative method, and combined way of controlling to control those insect pests tested in this study.

• The Korean Journal of Pesticide Science
• /
• v.15 no.2
• /
• pp.194-200
• /
• 2011

Diamondback moth (DBM, Plutella xylostella L.) is known as the most destructive pest of cruciferous crops worldwide. As most insecticides targeted to mainly larval stage, new insecticides which have hatching-inhibitory or ovicidal activity could be more efficient to control DBM. Therefore, we developed an easy and efficient method for screening ovicidal activity of DBM eggs using aluminum foil. The aluminum foil ($4{\times}12$ cm) coated with filtered juice of chinese cabbage leave (hereinafter called oviposition foil) exposed to 300 newly-emerged adults for 24 hours inside the rearing container. The oviposition foils were replaced every 4 days consecutively after mating, but it was better to discarded over then. Oviposition foil were divided into 6 to 12 pieces depending on egg mass volume. After dipping into test solutions for 10 seconds using faucet, oviposition foil pieces were placed into common petri dish, and then investigated hatchability. The effect of methanol solvent (50%) for 10 seconds dipping on the toxicity against DBM eggs was negligible. In addition, whether covering the petri dish or not should be dependent on nature of active compounds tested. With applying the new bioassay method, methanol extracts from 50 plants were tested the ovicidal activity to DBM eggs. Among them, four plant extracts; Angelica tenuissima root, Lycium chinense root, Cnidium officinale root and Polygala tenuifolia root, showed high ovicidal activity of over 90% control efficacy, against DBM eggs.

• Journal of Sericultural and Entomological Science
• /
• v.46 no.2
• /
• pp.54-57
• /
• 2004

A new silkworm variety "Buhungjam" for autumn rearing season is $F_1$ hybrid between Jam149, a japanese race bred from introduction breeding and Jam150, a chinese race from introduction breeding. Jam149, japanese parent of the "Buhungjam" showed high GCA in pupation percentage, cocoon shell percentage and filament length and Jam15, chinese parent showed high GCA in cocoon shell percentage and cocoon filament length. In the local adaptability test performed at 8 local areas in spring of 2003, Buhungjam records 7% higher in cocoon yield and 8% in raw silk yield than the check variety, Daesungjam.

• The Korean Journal of Malacology
• /
• v.21 no.2 s.34
• /
• pp.107-111
• /
• 2005

In the present study, the fecundation and fertilization behaviors of the trumpet shell, Charonia fampas sauliae were observed from November 2003 to March 2004. Female has multiple fecundation and multiple fertilization, and the fertilization continued for two days. The fertilized female stayed with the egg mass to protect the eggs, and the fecundation was made during the fertilization. The highest survival rate of egg capsule was 60% at $15^{\circ}C$. Charonia lampas sauliae fed with Chaetoceros calcitrans, Isochysis galbana, and Pavlova lutheri. Growth and survival rates of C. lampas sauliae in the conditions of various water temperature were observed. The highest survival rate was 23% at $15^{\circ}C$ reared for 60 days. The growth was presented in the $15^{\circ}C$ group, with shell length from $408{\pm}21.52{\mu}m\;to\;625{\pm}19.76{\mu}m$ during the experiment.

• Korean Journal of Ichthyology
• /
• v.24 no.2
• /
• pp.67-76
• /
• 2012

Skeletal development in the oblong rockfish, Sebastes oblongus, was studied based on extensive larval rearing conditions from December 2007 to March 2008. Newly-hatched larvae lacked osteological elements. After 3 days of bearing, jaw bones were ossified almost simultaneously with the frontal, parietal, clavicle, opercle, preopercle and branchiostegal rays at 8.0 mm average total length (TL). Ossification of the opercular was completed by 12.3 mm and the full complement of ossified elements of cranium and pectoral girdle were completed by 16.2 mm. Ossification of the cartilaginous caudal complex began to at 9.8 mm, and completely ossified by 18.0 mm. The fusing of the first and second, and the third and fourth hypurals initially occurred by 10.8 mm, and their fusion was finally completed at 18.0 mm. Notochord flexion occurred and formed an individual centrum by 8.5 mm and 10.8 mm, respectively, and all 26 centra were ossified by 13.2 mm. The preorbital bone began to ossify on the anterior region of eye at 10.8 mm, and the $1^{st}$ suborbital bone appeared ossified on the lower of eye by 12.3 mm, and all elements were ossified at 27.5 mm. Finally, after 71 days of bearing, the juveniles became 27.5 mm, and ossification was completed at this stage.

• Journal of Aquaculture
• /
• v.20 no.3
• /
• pp.168-172
• /
• 2007

Two zooplankton species Brachionus rotundiformis (rotifera) and Tigriopus japonicus (copepoda; harpacticoida) were commonly used as live food organisms in the marine larval rearing centers. The combination culture method of two live food organisms (B. rotundiformis and T. japonicus) was well known as very valuable for stable and mass cultures. In this study, we investigated the effects of photoperiod exchanges on the growth and interspecific relationship in the combination culture of two species. The results showed that, photoperiod condition can change copepod (and rotifer) density under the two species combination cultures. There is 200% higher maximum rotifer density on the 24L:0D photoperiod culture condition compare to 12L:12D condition. However, maximum density of copepod is observed highest on the 0L:24D photoperiod culture condition. In addition, it's differ in the culture densities of nauplii, copepodites and female carrying eggs on the each three photoperiod types.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.45 no.3
• /
• pp.271-282
• /
• 2012

Early osteological development of the skull, vertebral column, and fins, and squamation in the spotted sea bass, Lateolabrax maculates, were studied under extensive larval rearing conditions. The first ossification during cephalic skeleton development began with the premaxillary, dentary, and parasphenoid at 6.4 mm Total length (Notochord length 6.1 mm) and was completed by 25.2 mm TL (Standard length 20.3 mm). Ossification of the cartilaginous caudal complex started simultaneously in the urostyle and two preural centra at 12.2 mm TL (10.4 mm) and it was completely ossified by 32.0 mm TL (26.4 mm). The principal caudal fin rays, with a count of 9/8, began to ossify at 11.6 mm TL (10.2 mm) and the procurrent caudal fin rays, with counts of 4 (upper) and 3 (lower), started to ossify by 12.6 mm TL (10.9 mm). Ossification of these parts was completed by 21.4 mm TL (17.5 mm). Ossification of the vertebral column was first observed in the first to fourth centra at 8.3 mm TL (7.5 mm) and was fully completed by 21.7-35.0 mm TL (17.8-29.3 mm). The pectoral girdle started to ossify by 5.6 mm TL (5.4 mm) and was completed by 26.8 mm TL (21.8 mm). Eight pectoral fin rays were ossified at 11.6 mm TL (10.2 mm) and 16-18 rays were fully ossified by 13.8 mm TL (12.0 mm). Also, the dorsal, anal, and pelvic fin rays started to ossify at 12.2 mm TL (10.4 mm) and were completed by 12.8 mm TL (11.2 mm), 23.8 mm TL (19.4 mm), and 13.8 mm TL (12.0 mm), respectively. Ossification of the anal and dorsal pterygiophores initially occurred by 12.6 mm TL (10.9 mm) and 14.3 mm TL (12.2 mm), and was completed by 21.4 mm TL (17.5 mm) and 19.3 mm TL (15.9 mm), respectively. Squamation started at three centers of differentiation: the middle region of the trunk, the anterior of the caudal peduncle, and on the caudal peduncle at 23.8 mm TL (19.4 mm). The body was covered with scales, except the snout, at 57.2-60.2 mm TL (SL 47.1-49.2 mm).

• Journal of Aquaculture
• /
• v.20 no.4
• /
• pp.260-264
• /
• 2007

We investigated egg collection and the effects of water temperature (4, 7, 10, 13 and $16^{\circ}C$) on egg development, hatching and larval growth of Pacific cod Gadus macrocephalus under laboratory conditions. Fertilized eggs were round in shape ($1.01{\pm}0.03\;cm$) and adhesive to nylon nets. Fertilization rate was 68% by wet method. The time of egg development was negatively proportional to water temperature with the range of $4^{\circ}C$ to $13^{\circ}C$. Eggs hatched only at $7^{\circ}C$ after 288 hours of fertilization and $10^{\circ}C$ after 192 hours. Hatching rate was highest as 65% at $7^{\circ}C$ followed by $34.4^{\circ}C$ at $10^{\circ}C$. Survival rate was 18.3% at $7^{\circ}C$ and 5.2% at $10^{\circ}C$.

• Journal of Aquaculture
• /
• v.11 no.4
• /
• pp.521-528
• /
• 1998

The influence of starvation on survival, growth and feeding incidence of larval tiger puffer Takifugu rubripes was investigated for 16 days after let them hatched at the temperature of 16.5~18.5${\circ}C$. The effect by delayed initial feeding on larvace was also studied. Almost all larvae began to be fed from the stage of yolk absorption about 5 days after hatching, in which rearing trials revealed that their survival and growth were influenced by food availability. Survival of unfed larvae, which stated to decrease drastically since the oil globule was exhausted about 9 days after hatching, dropped to 50% and 0% respectively on the 11.5th and 16th day. the difference of growth between fed and unfed larvae came into sight on about 5th day after hatching when the initial feeding was started, and had reduced in proportion to the length of starvation period. The condition factors for the unfed larvae were lower than thost of the fed. Of the larvae which had starved less than 5 days, more than 80% could consume food upon feeding. No fish had the ability in having food after 10 days. It appeared that the turning point of recover for the starving larvae came on 7th or 8th day. Their taking-food ability seemed to be affected by the change in swimming activity which depended on the duration of starvation. For the seed production of tiger puffer, therefore, feeding should be initiated as soon as possible, so as to enhance the production and survival of healthy seeds.