• Journal of Sericultural and Entomological Science
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• v.25 no.1
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• pp.21-26
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• 1983

The mulberry variety, Jeonweon No. 1, has been cultivated in some parts of Ho-Nam District since the variety was selected at the Jeonbuk Provincial Silkworm Egg Production Station in the latter half of 1920s. However, the characteristics of the ariety have not been reported. Therefore, the cultivation experiment on the variety was carried out to investigate the characteristics of the variety at Jeonju and Suweon for four years from 1979 to 1982. 1. The mulberry variety, Jeonweon No. 1, belongs to the Morus alba L. and the sprouting stage is medium. 2. The branch growth of the variety was rather slow, however the number of branches was more and the posture of branches opened wide. 3. The rate of cold injury of shoot tips was a little high, but resistance to disease and the lodging of branches was weaker, compared with the Gaeryangbbong variety. 4. The annual yield of leaves of the variety per 10a was 1,474kg, 14% less than that of the Gaeryangbbong variety.

• Journal of Sericultural and Entomological Science
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• v.30 no.2
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• pp.96-104
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• 1988

Vitellin, the major yolk protein of the silkworm, Bombyx mori was pruified, and its immunological properties and the quantitative changes during embryogenesis were studied. The ovary transplantation into male hosts was also carried out to find its effect on the yolk protein synthesis. The pupal vitellogenin and the egg vitellin of Bombyx mori were purified by DEAE-cellulose column chromatography. These two female specific proteins showed the same mobility in the polyacrylamide gel electrophoresis and the same reaction in the double immunodiffusion test. The immunological identity was also observed between the vitellins of Bombyx mori and Bombyx mandarina. The rudimentary ovaries transplanted into the male hosts of silkworms produced eggs without vitellin, indicating that the yolk precursors synthesized in other female organ beyond the ovary were necessary to produce vitellins. The major yolk protein, vitellin was disintegrated and utilized mostly during late stage of embryogenesis. It was different characteristics from the egg specific protein, which was utilized continuously from the early embryonic stage.

• Korean journal of applied entomology
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• v.45 no.3 s.144
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• pp.283-291
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• 2006

The efficiency to detect mutagenicity of the system using a specific locus mutation of Bombyx mori was examined and improved. In the system, mutagenicity could be detected by the egg colour manifested by the pe and/or re genes, which is a kind of recessive visible mutation of the insect. Among tested four mutagens, MMC had specially high sensitivity in the oocytes of silkworm and EMS had in the spermatozoa. PCB and dioxin showed a positive effect in both the oocytes and spermatozoa. In a consequence of sensitivity of mutagen by mating number of male moth of B. mori, treated mutagen, there was no difference between one mating - and three mating - male moth in sensitivity of mutagen. Sun3ho, B. mori variety, which showed high sensitivity to mutagens was improved in the major characteristics by crossing of C5 and N12.

• Journal of Sericultural and Entomological Science
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• v.53 no.1
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• pp.12-18
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• 2015

This study was conducted to consider practical use of F2 hybrid and intervariety crossing for the improvement of silkworm eggs export and silkworm eggs manufacture. Now Kumokjam and Baegokjam come into wide use to sericulture farmers but comparison test of F1, F2 hybrid and intervariety have not been done. We weighed against the productivity among economical character. While larval period of F2 among them is most long time, pupation percentage and cocoon yield per 10,000 3rd molted larvae are lower than intervariety. With comparing F2 and intervariety, single cocoon weight of F2 is lower 9 ~ 21% than intervariety, and cocoon shell weight of F2 was lower 10 ~ 18% than intervariety. By number of cocoons per liter, F2 hybrid was lower and more irregular size than intervariety. In coparison with number of egg laid, F2 hybrid Baegokjam was 655 ea (14%) and Kumokjam 625 ea (40%) more than F1 hybrid. Also, F2 hybrid for filament grade went down than F1 hybrid. The advantage of egg production in F2 hybrid can reduce costs because there is no necessity for sex discrimination and germination control. But besides increase of number of egg laid, the productivity including economical characters was greatly lowered. Except for being a lot of laying eggs, cocoon productivity of the F2 was greatly reduced by degeneration of practical traits. Therefore the further studies are needed in order to increase utilization value of the F2 hybrid silkworm.

• Korean journal of applied entomology
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• v.24 no.1 s.62
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• pp.34-38
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• 1985

Effects of some artificial diets containing pulverized silkworm pupae On the oviposition of a green lacewing, Chrysopa formosa, were studied. The pulverized silkworm pupae with honey seemed to be a good diet for the egg-laying activity of field-collected adults in the beginning of rearing, but their fecundity progressively decreased. Newly emerged adults. did. not lay eggs when fed the above diet, but they were able to lay eggs when the silkworm pupae were defatted and provided with honey. An adult female laid an average of 166.8, 110.2, 96.1, and 66.1 eggs after spending 5, 9, 9, and 11 days for the initiation of oviposition when supplied with various diets i.e. the cabbage aphid, defatted silkworm pupae with additive constituents, mixture of intact and defatted silkworm pupae with additive constituents, and defatted silkworm pupae with honey, respectively.

• International Journal of Industrial Entomology and Biomaterials
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• v.46 no.1
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• pp.16-23
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• 2023

The silkworm's dormancy and embryonic development are accomplished through the interaction of various genes. Analysis of the expression of several interacting genes can predict the embryonic stage of silkworms. In this study, we analyzed the changes in the expression level of genes at each stage during the embryonic development of dormant silkworm eggs and selected genes that can predict the hatching time. Jam123 and Jam124 silkworms were collected after egg laying, and the silkworm eggs were preserved using a double refrigeration method and expression analysis was performed for 23 genes during embryogenesis. There were 5 genes showing significant changes during embryogenesis: UDP-glucuronosyltransferases (BmUGTs), heat shock protein hsp20.8 (BmHsp20.8), Cytochromes b5-like proteins (BmCytb5), Krüppel homolog 1 (BmKr-h1), and cuticular protein RR-1 motif 41 (BmCpr41). As a result of quantitative comparison of the expression levels of these 5 genes through real-time PCR, the BmUGTs gene showed a difference between Jam123 and Jam124, making it difficult to see it as an indicator for predicting hatching time. However, the BmHsp20.8 gene had a common expression decreased at the imminent hatching stage. In addition, it was confirmed that the expression level of the BmCytb5 gene decreased to the lowest level at the time of imminent hatching, and the expression of the BmKr-h gene was made only at the time of imminent hatching. The expression of the last BmCpr41 gene can be confirmed only at the time of imminent hatching, and it was confirmed that it shows a rapid increase right before hatching. Taken together, these results suggest that expression analysis of BmHsp20.8, BmCytb5, BmKr-h1, and BmCpr41 genes can determine the stage of embryogenesis, predict hatching time, which facilitate better management of silkworm eggs.

• International Journal of Industrial Entomology and Biomaterials
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• v.11 no.2
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• pp.107-111
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• 2005

Impact of microsporidian infection and season on reproductive potential of Bombyx mori L. was investigated in the laboratory. Microsporidian infection significantly (P<0.01) reduced fecundity and hatching and increased sterility and mortality of eggs. Among the microsporidia, Nosema sp. 2 infected silkworm produced eggs with least fecundity and hatching percent as well as highest dead and sterile eggs followed by Nosema sp. 1 and N. bombycis. Microsporidia, in general, significantly reduced fecundity and hatching percent of eggs and increased number of dead and sterile eggs in all the three seasons except N. bombycis in July - August (S3) and Nosema sp. 2 in January February (S1). Since, seed production is the anchor sheet of mulberry sericulture, coefficient of egg lying is considered as an important aspect and the industry quite often facing shortage of disease free layings. The present study indicates that B. mori is more susceptible to microsporidia during S2 followed by S3 and S1 and Nosema sp2. is most virulent followed by Nosema spl. and N. bombycis.

• Journal of Sericultural and Entomological Science
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• v.38 no.2
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• pp.124-129
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• 1996

Oral application of dimethyl sulfoxide in different concentration (1, 3 and 5 percent) to silkworm, Bomyx mori at the fourth and the fifth instar has significantly increased the commercial characters such as larval and silkgland weights, female and male cocoon weights, their shell weights and egg production. However, larval duration, cocooning and hatching percentages did not showed any significant change, as compared with that of the corresponding parameters of the carrier control. Similarly the glycogen and protein contents of the fat body and trehalose and protein contents of the haemolymph were significantly increased in 1 and 3 percent, whereas the increase of them in 5 percent concentration did not take place significantly, except haemolymph trehalose where it was found to be significant, as compared with that of carrier control.

• International Journal of Industrial Entomology and Biomaterials
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• v.13 no.2
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• pp.51-55
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• 2006

Since 1970, China has become the biggest cocoon producer in the world, and made the highest historical record of cocoon output for 759,800 tons in 1995. However, in 1996 cocoon production reduced sharply to 470,900 tons. After a ten-year adjustment and reform, sericultural areas have shifted from developed regions to developing regions and from the east to the west. From 2000, the cocoon output has started to increase restoringly. By 2004 it recovered to 547,091 tons. With the development of market economy, sericulture management has been changed, including mulberry fields concentrated to the specializated households and cooperatives, cocoons produced in larger scale instead of individuals, Silkworm egg producing enterprises gradually changed into non-governmental joint-stock ones. The mechanism of market cocoon price has been gradually established. The management model of combination of trade, industry and agriculture is pushing and improving. It is the fruit of modern science and technology, especially sericultural basic research, that provides China's sericulture with the opportunity and vital force. China's sericulture, therefore, will continue to develop steadily in future.

• Proceedings of the Korean Society of Sericultural Science Conference
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• 2003.04a
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• pp.54-54
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• 2003

DNJ concentration in silkworm, Bombyx mori was traced through the life. DNJ absent in egg existed over the concentration of 5 mg gdw-1 from 1st instar to 4th day of 5th instar during larva period. DNJ concentration decreased drastically with body weight about at 7-8th day of 5th instar when silk production became a major process. (omitted)