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

• Journal of Sericultural and Entomological Science
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• v.2
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• pp.1-31
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• 1962

The purpose of this treatise is to prove the presence of cystine in silk fiber through wide sampling throughout all the sericultural processes of Bombyx mori.; also to show that disulfide cross linkages exist in the silk fiber. The conclusions reached were as follows: 1. Crystalline cystine was obtained from silk fibroin using Folin's Method. 2. Analytical data showing the cystine content of silk fiber and its related materials were obtained using Sullvan's Method as follows: Material Percent Cystine A. Mulberry leaf protein 0.175 B. Silkworm egg 0.33 C. Silkworm Body, matured, fat extracted, without silk gland 0.41 D. Silk gland, matured 1.23 E. Silkworm feces none F. Silkworm pupa, fat extracted 0.30 G. Silkworm moth, fat extracted 0.60 H. Raw Silk 0.22 I. Fibroin 0.175 J. Sericin 0.30 3. The presence of cystine in the silkworm was substantiated the existence of 0.175 % methionine in mulberry leaves and 0.12% methionine in the silk gland. 4. Part of the sulfhydryl compounds in the silk gland is believed to transfer to serine and methionine, with the former being secreted into the liquid silk finally as silk fiber and the latter used for nutritive purposes in the growing of silk gland tissue. 5. The cystine content is variable by mulberry species, silkworm species, sex, breeding process, and other culturing environments. 6. Hybrid silkworms require more nutritive amino acids for effective growth than the original parents, and secrete less of them as silk fiber. 7. From such an observation, the amino acid composition of silk fiber is believed to be fairly flexible. Cystine if included in the amorphous part of the fiber, especially in sericin. 8. The result from enriching the silkworm diet with pure cystine or wool cystine did not result in any advantage, therefore it is believed that the natural cystine and methionine contents in the mulberry leafaregoodenoughforsilkwormnutrition. 9. The disulfide cross linkage in silk fiber was verified by using the Harris Method. Contraction took place following the treatment of the fiber with various salts and acids. Comparisons were made with wool fiber. 10. During these experiments, the fibrious structure of silk fiber and the net-globular liquid form were photographed microscopically. It is believed that the globules of liquid silk are net-formed by the inter attraction of the OH ion of the globular peptide and the H ion of water as shown by the hair cracking behavior of the film. The net-globular protein precipitation from the mulberry protein solution showed that mulberry is a proper diet for the formation of fibrous protein in the silk fiber. 11. The significance of the presence of cystine in silk fiber as emphasized in this paper should result in modification of the general conception that cystine is absent from this fiber. NOTICE: A part of this treatise was presented at the annual Korea Sericultural Society meeting held in 1961.

• Journal of Sericultural and Entomological Science
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• v.4
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• pp.69-78
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• 1965

1. In younger larval stages, the incubation period of Spicaria pracina was showed to generally last for 8 days after the inoculation of 1st instar, for 11 days after that of 2nd instar, and for 12 days after that of 3rd instar. 2. The more the inoculum of spore is, the more silkworm jundices appear severely throughout all stage except 1st instar. 3. Especially in matured larval stages, more death rate due to silkworm jundice was showed to appear than that due to green muscardine and the more the larvae became mature, the more the loss due to jundice were severe. 4. Among other inoculum, the control by 5 per cent cerisan lime resulted in getting the best economical effect while this chemicals did harm to the silkworms, being of 20.1 per cent death rate.

• Proceedings of the Korean Society of Sericultural Science Conference
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• 1997.06a
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• pp.51-72
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• 1997

Diapause hormone (DH) is a neuropeptide hormone which is secreted from the suboesophageal ganglion (SG) and is responsible for induction of embryonic diapause of the silkworm, Bombyx mori. DH is isolated from SGs and determined to be a 24 amino acid peptide amide. The cDNA encodes the polyprotein precursor from which DH, pheromone biosynthesis activating neuropeptide (PBAN) and three other neuropeptides are released and become matured. The C-terminal FXPRL-NH2 sequence of DH is essential but not sufficient for expression of full activity. Recently, we have isolated a unique hydrohobic peptide (VAP peptide) with a slight diapause egg induceing activity from organic solvent extracts of the male adult heads of the silkworm. The VAP peptide itself has no diapause inducing activity, but enhances DH activity through reducing ED50 value and the threshold concentration of DH. The DH-PBAN gene is composed of 6 exons interrupted by 5 introns and is expressed in 12 neurosecretory cells of the SG. The incubation of eggs at 25$^{\circ}C$, which induces embryonic diapause in the progeny, caused DH-PBAN mRNA content to increase at 5 different stages in the life cycle. By contrast, a 15$^{\circ}C$ incubation only induced expression of the gene at the late phrase adult stage. The temperature-controlled expression of DH-PBAN gene is closely correlated to the incidence of diapause, indicating that DH-PBAN gene expression is the initial event leading to diapause induction. DH acts to stimulate trehalase activity in developing ovary to bring about hyprglycogenism in mature eggs, a prerequisite metabolism for diapause initiation. Using in vivo and in vitro systems, DH is clearly shown to induce trehalase gene expression in developing ovaries. New protein synthesis is not needed for this process, but a Ca2+-dependent proteinkinase seems to be involved. Quite recently, we have sucessfully applied a new and potent trehalase inhibitor (Trehazoline) to reudce glycogen content in developing ovaries. The eggs deficient in glycogen were also able to enter diapause as the natural eggs do, so that we could provide the new egg system to reconsider the diapause associated metabolism other than the glycogen-sorbitol metabolic system.

• International Journal of Industrial Entomology and Biomaterials
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• v.4 no.1
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• pp.19-22
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• 2002

Rotary mountages are the best mountages among all the mountages that are used in sericultural areas. But to use this mountage more space, separate mounting hall & requires more labour to pickup the matured worms. to over come these problems, self mounting method is adopted to save the time Er labour, But the mounting rate is generally less. To accelerate the mounting rate different repellents viz; saw dust, phytoecdysone, 1% cresol with paddy husk, lime, kaolin, gormalin chaff were used in the present study. The results indicated that highest number of larvae climbed the mountage in 1% cresol with paddy husk, followed by phytoecdysone and lime. It is observed that the use of repellents at wandering stage accilerates mounting rate and did not affect the quality of the cocoons and reeling characters.

• Journal of Sericultural and Entomological Science
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• v.20 no.2
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• pp.26-31
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• 1978

The objective of the present study was to investigate the effect of nicotine-contaminated mulberry-leaf, which was grown in the vicinity of tobacco drying plant (TDP), on cocoon crop. Mulberry-leaf harvested from the field at Sericultural Experiment Station (SES), Suweon, Korea, was used as control, supposedly nicotine-free leaf. Leaf harvested from the field in the distances of 30-50m, 300-400m and 700-800m from TDP was fed during the whole larval stage of the silkworm at. SES. The effect of leaf in each treatment level on the quantitative characters of the silkworm was summarized as follows; 1. Larval duration from 4th instar on was significantly longer in the TDP-leaf treatments than for the control. 2. Duration of matured silkworm appearance became longer as the distance of the mulberry-field from TDP got shorter, because the larval duration and growth of the silkworm were not uniform in the TDP-leaf treatments. 3. Mortality rates during the late larval, cocoon spinning, and pupal stages were highest for the 30-50m leaf, especially mortality rates during the late larval and pupal stage were serious. 4. Pupation rate was lowest for the 30-50m leaf and those for the 300-400m and the 700-800m leaf were not significantly different from that of the control. 5. Nicotine damage to cocoon weight and cocoon shell weight was significant in each TDP-leaf level. Cocoon shell ratio was reduced at the same extent in each level, compared with the control. 6. The ratio among cocoon-classes was significantly different between treatments, compared with best-cocoon ratio of 87.1% for the control. Cocoons were not uniform for the 30-50m leaf, and those for the 300-400m and the 700-800m leaf were as almost uniform as those for the control. 7. Loss of fresh cocoon yield became greater as the distance of the mulberry-field from the TDP-got shorter. In conclusion, the critical distance of mulberry-field, which influences larval health, cocoon quality and yield, appeared to be 800m from the TDP. Such other factors as wind direction and topographic location may be involved in the critical distance. 8. From the present experiment, we could obtain only the effect of nicotine on the silkworm through digestive system, since the silkworm was raised at SES in Suweon. If the silkworm.. were raised in the vicinity of the TDP, poison effect of nicotine on the silkworm could beo expected through exoskeleton and tracheal system as well as through digestive system.

• Journal of Sericultural and Entomological Science
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• v.45 no.2
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• pp.108-111
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• 2003

A infectious fungus (J131) recently isolated from artificial cultivation farms of Paecilomyces tenuipes is known to cause a great yield loss and deterioration of products. In this study, its occurrence and characterization were made. The isolate (J131) was identified as Paecilomyces farinosus (Holm ex S. F. Gray) Brown ＆ Smith. Colonies of the isolate on PDA grew moderately fast, attaining a diameter of 19mm within 14 days at 24${\pm}$1$^{\circ}C$. Vegetative hyphae are smooth-walled and hyaline. Conidiophores mainly arose from the submerged mycelium, usually measuring 1.3-1.5$\mu\textrm{m}$ wide and consisted of verticillate branches with whorls of 2 to 4 phialides. Phialides of 3.8-5.8${\times}$1.5-1.8 $\mu\textrm{m}$, with a swollen basal portion tapered into a distinct neck of about 0.6-0.8 $\mu\textrm{m}$ wide. Conidia arisen from the phialides, were ellipsoidal to fusiform, smooth-walled, hyaline, 1.8-2.4${\times}$1.1-1.4$\mu\textrm{m}$. .When silkworm larvae were injected with concentration of 1${\times}$10$\^$8/ conidia/$m\ell$ of infectious fungus J131, infection rate was 41.3％ and synnemata formation rate was 23.6％. Black spots were appeared on the surface of silkworm larvae in 5-9 days after injection. The surface of larvae was covered with hyphae which were gradually turned into yellow from white color during the incubation period of 3-4 days. 1 to several 4-6mm long synnemata of yellow or orange color were formed on the surface. The matured synnemata were ramified from its end and produced much conidia of white color.

• Journal of Sericultural and Entomological Science
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• v.4
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• pp.97-101
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• 1965

This work was carried out to investigate the relation between the fat content and the metamorphosis as the silkworms grew. The results obtained are as follows: 1. The content, of which the dry matter had been 24% at the stage of newly hatched silkworms, were gradually decreased by feeding on, but suddenly increased to the 28.5% at the mature stage. Those decreased slightly from pupation to just before the moths, and again increased to the 32% of the dry matter when became the moths. 2. The content, of which the fat had been 16.2%, however, decreased as the silkworms grew. The fat content increased little by little from the first feeding to the vigorous eating, but the matured worm contained only 15.7% of the fat. 3. The fat content of both male and female showed an increase to 23.5% and 35.7%, respectively. After that, the contents of it decreased to 12% and suddenly increased to 26% just before the moth in female. In male the content of fat showed a slight increase till before the moth, and after moth became, it were 42.5%.