• Journal of Sericultural and Entomological Science
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• v.34 no.2
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• pp.13-19
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• 1992

This study was investigated the relationship between egg size and manifestation of quantitative characteristics such as larval growth, cocoon weight and cocoon shell weight etc. There was a high positive correlation between egg size and body weight of newly hatched larva. Until 2nd instar, larval growth was affected by egg size. The body weight of grown larva from big eggs were heavier on all strains except for strain El6 and the larval duration from big egg were shorter on the Japanese and the Chinese skins. These facts show that the characteristics of larval body weight and larval duration were affected more by the strain than by the egg size. The cocoon characteristics of big eggs were better in comparison than those of regular eggs.

• Proceedings of the Korean Society of Sericultural Science Conference
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• 2003.10a
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• pp.104-105
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• 2003

In order to breed high yielding good quality leaves mulberry cultivar, which is essential for silkworm rearing, the characteristics of newly bred mulberry strain were surveyed. Materials and Methods: materials -Mulberry Jamgsang 123 which is registered as newly bred mulbery cultivar Suilppong -Sikworm Baegogjam nd Daesungjam were reared for practical leaves quality examination in spring and autumn, respectively by feeding Jamsang 123 leaves (omitted)

• Journal of Sericultural and Entomological Science
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• v.8
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• pp.63-67
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• 1968

The aim of this treatise was to find out the factors related to the weight of a have in the original silkworm. The results obtained are as follows: 1. There is no relationship between the degumming rate and cocoon layer rate, but there is related with the weight of cocoon only in chinese strain. 2. There is no difference among the strains, but considerably differente in degumming rate among the species. 3. The degumming rate of female is higher than that of male.

• International Journal of Industrial Entomology and Biomaterials
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• v.13 no.1
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• pp.7-14
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• 2006

A breeding programme was initiated during 2001 to introduce sex-limited larval markings to a productive multivoltine breed - BL67 from an inbred sex-limited line, MY1 (SL) maintained at Central Sericultural Research and Training Institute, Mysore. Introgressive hybridization, recurrent backcrossing for six generations followed by sib-mating resulted in synthesis of a new multivoltine silkworm breed BL67 (SL) with sex-limited larval markings. The new breed was studied for combining ability by crossing with eight bivoltine breeds viz., $NB_4D_2,\;CSR_2,\;CSR_2 (SL),\;CSR_2,\;CSR_4,\;CSR_8,\;CSR_{18}\;and\;CSR_{19}$. General combining ability effects of the new breed showed its superiority over the popular Pure Mysore by expressing significant GCA effects for six out of twelve characters whereas the results are on par with the original multivoltine breed. The hybrid $BL67(SL){\times}CSR2(SL)$ excelled in several quantitative characters such as pupation rate (90.2%), cocoon weight (1.97 g), cocoon shell weight (40 cg), cocoon shell ratio (20.3%), filament length (918 m), denier (2.96), raw silk percentage (14.96%) and neatness (90 p). Studies on cocoon size variability revealed that the cocoons of $BL67(SL){\times}CSR2(SL)$ were found comparatively uniform showing less standard deviation of 6.55 and co-efficient of variation of 3.91 %. The suitability of newly developed breed for easy grain age operation and commercial exploitation with promising hybrid have been discussed.

• Journal of Sericultural and Entomological Science
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• v.23 no.1
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• pp.32-37
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• 1981

It is necessary to improve new silkworm variety suitable for the artificial diet different from the mulberry leaves in physical and chemical natures. The silkworms fed on artificial diet show low productivity in general. So the effectiveness of selection for cocoon characters was studied when the silkworms were reared on the artificial diet for several generations. The results obtained are as fellows: 1. There is no correlation between the cocoon shell weight and the cocoon shell percentage in female cocoons of both Sa and Y strains but in male cocoons. 2. No correlation exists between the weight of a cocoon and a cocoon shell percentage of male cocoons in Sa strain. 3. There is a specific effect of the artificial diet on selection between Japanese and Chinese strains compared with the mulberry leave rearing. 4. The cocoon quality of first generation in artificial diet rearing was very inferier to that of previous generation in mulberry leave rearing in both Sa and Y strains, but the effect of selection rapidly increased in first and second generation.5. Very high mortality was noted in 4th generation to the degree of hardness for successive generation. 6. From 6th generation to 10th generation, the effectiveness of selection for cocoon characters increased continuously except the cocoon shell percteage.

• Journal of Sericultural and Entomological Science
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• v.51 no.2
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• pp.211-217
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• 2013

In general, the mean silkmoth lifespan is around 8 days for female and 5 days for male. But, the duration of J037 strain's lifespan is remarkably long in both sexes. On the contrary, the Daizo(sdi) strain has a remarkably short lifetime. The differences in adult lifetime among various silkworm strains has been suggested that the adult lifetime may be genetically controlled. In this experiment, using J037 and Daizo strains we investigated genetic factors related to the adult lifetime of silkworm. We constructed the full-length cDNA library from the adult male of the J037 strain. A total of 2,688 clones were randomly selected, and we performed a differential display hybridization with cDNA probes generated from J037 and Daizo adult males. In conclusion, 193 clones were identified as differential expressed genes, and 154 unique genes were generated after the assembly of 193 clones. Of the 154 unique genes, the most abundant genes were cytochrome oxidase subunit-1 gene(9 times) and unknown(clone ID; 1-50) gene(5 times). The functional groups of these unique genes with matches in the AmiGo database were constructed according to their putative molecular functions. Among thirteen functional categories, the largest group was unclassified protein(24%). In addition, we analyzed the nucleotide and deduced amino acid sequences of the most highly occurred gene(1-50, EF434397), which consisted of 240 amino acids. However, it is confirmed yet that these genes really have an affected on the silkworms longevity. Further studies on these molecules biological roles will give us well-fined information about mechanisms of insect aging and/or scenesence.

• Journal of Sericultural and Entomological Science
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• v.41 no.1
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• pp.20-28
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• 1999

Color qualities investigated on the basis of Munsell code and Korean standard color code for the cocoons from various strain of mulberry silkworm, Bombyx mori. 16 of different color qualities were identified from 21 of original silworm strains, and determinated international name with the revision of Korean color name for cocoon. The various cocoon color confirmed on the sphere from 567 to 593 nm wavelength, 78% of those located at the region about 580 nm (575~584) of sensitive "color difference limen". Y gene engaged broad ranges of wavelength (575~593 nm) in the color expression, by contrast with other genes of Pk (593 nm), F (584~593), Grc and relative G group (567~570 nm), on the transmission of carotenoid or flavonoid color substance. YC gene expression by original silk worm strain was also distinguished by those variation of specific yellow than other colors from Grc, GaGb, Gc, and YPkF. Appearance of chrome yellow cocoon was dominant than other yellow in the cross among vivid yellow group. F1 of pin${\times}$green produced the cocoon of yellow such as "additive mixture" as color light, however, most of the hybrid between yellow cocoon showed the color similar to "subtractive mixture" as a mixture of dyestuff. Hybrid cocoons among yellow or green colors were decreased their hue, value, and chroma, than those of parent. Diallel cross among the strain of various green cocoon suggest the existence of Grc, Ga, Gb, Gc genes. Cream colored cocoon of B. mandarina was differed from other yellow cocoon of Bobyx mori B. mori. Y$^A$ with Ymc showed the similar role of Y with C, therefore, segregated yellow cocoon from the B. mori${\times}$B. mandarina (+$^YC/Y^AYmc$). YC expression of $Y^AY$mc genes might be suppressed by deficiency of outer layer sericin on the middle division of silk giand in the B. mandarina.

• Journal of Sericultural and Entomological Science
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• v.2
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• pp.41-47
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• 1962

This work was carried out to investigate the phenotypic, genotypic, and environmental correlations between the number of the egg markings and other metric characters, and their heritability, with eight varieties in Bombyx mori L. Five European varieties, ten Chinese varieties and ten Japanese varieties were used to know the average number of the egg markings and their variabilities for each strains. The results may be summarized as follows: 1) there were highly negatively phenotypic and genotypic correlations between the number of the egg markings and total cocoon weight, weight of cocoon layer, or denier, but not an environmental correlation. 2) The average number of the egg markings in Chinese strain was more than that in other strains. 3) The correlation between the motality and the number of egg markings seemed not to be found. 4) The heritability of the weight of cocoon layer and the bave length was less than that of total cocoon weight, denier and number of egg markings. 5) The more the number of the polyhedral particles in an egg marking group became, the more the total number of egg markings increased. 6) The variation of the number of the egg markings in European strain was larger than that in any other strains. 7) It is expected that the selection for the number of the egg markings may have genetic advances of total cocoon weight, weight of cocoon layer, or denier. Especially the selection for the number of the egg markings before rearing will save the silkworm rearing cost.

• Journal of Sericultural and Entomological Science
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• v.7
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• pp.49-52
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• 1967

In the F$_1$ hybrids and parents of silkworms, the silkworms of 47 blocks in summer and 68 blocks in fall in 1965 were reared in order to know the effect of mortality on the difference of sex ratio. The results analyzed are as follows; 1. In Moran of Japanese strain-parent and Morean x Daedong of F$_1$ hybrid, there is of no effect of an increase and decrease of mortality on the sex ratio. So male is not always stronger than female. 2. In Daedong of Chinese strain-parent, the more the mortality in the blocks is, the higher the survival ratio of male pupa becomes. (Y=0.233x-41.67). 3. As the results mentioned above, the present investigation method of cocoon quality of Chinese strains with the same number of cocoons of both sexes will have to be considered again, according to the cocoon crops, as far as concerned with the reasonable sampling from the population.

• International Journal of Industrial Entomology and Biomaterials
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• v.9 no.2
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• pp.217-223
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• 2004

A cathepsin L-like cysteine protease, v-cath, encoded by the baculovirus has been shown to playa role in host liquefaction. We have identified a v-cath gene in the silkworm virus, Bombyx mori nuclear polyhedrosis virus (BmNPV) K1 strain. The 969 bp v-cath has an open reading frame of 323 amino acids. A putative cleavage site and catalytic sites were conserved in BmNPV-K1 v-cath. The predicted three-dimensional structure of BmNPV-K1 v-cath revealed that the overall fold of BmNPV-K1 v-cath is similar to that of other proteases of the papain family. The deduced amino acid sequence of BmNPV-K1 v-cath showed 98% and 97% protein sequence identity to BmNPV T3 strain and to Autographa californica nuclear polyhedrosis virus, respectively. The BmNPV-K1 v-cath differed at 4 amino acid positions from BmNPV T3. The v-cath gene in BmNPV-K1 genome is located on the EcoRV 6 kb and XhoI 9 kb fragments. Northern hybridization analysis of BmNPV K1 v-cath gene revealed that it is expressed late in infection.