• Journal of Sericultural and Entomological Science
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• v.17 no.1
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• pp.47-53
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• 1975

This experiment was carried out to obtain a marked larvae in sex-limited inheritance, using F$_1$ hybrid Bo ok X Chun san introduced from Japan. Sequence of backcrossing has been done through the earlier generation with a recessive character of plain marked larvae. 1. It is noted that genotypic segregation of sex-limited larval marking was observed in F$_4$ generation; female possesses larval marking and male shows a plain marking. 2. Larval marking heredity follows a diagram of segregation with an expected genotype such as ♀ ： (W$.$＋p)/Z$.$P/P and ♂ ： Z/Z$.$P/P. 3. It is observed that dissociation was occurred to produce female with a genotype of W/Z$.$P/P in segregation ana selection. 4. Abnormal ratio of sexuality is observed in the course of segregation and segregation and analysis of it is continuously under way. 5, It is observed that the difference of qualitative characteristics between female and male obtained from the original variety shows the same tendency as the normal marked variety.

• Journal of Sericultural and Entomological Science
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• v.16 no.1
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• pp.49-55
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• 1974

Studies on the harvest methods for the branch-rearing in autumn are as follows. (1) It turned out to be the best method in the early autumn to thin one to two of the normal branches or the dwarf ones, or pick off some of leaves for the yields, according to the rearing scale. (2) For the rearing of the silkworm larvae at 4th instar, it is recommendable to apply one of the following harvest methods, such as the thinning of dwarf branches, the thinning of some branches, intermediate cutting, and the pick-of of the leaves at low part of mulberry in the regards io the quality of leaves and the labour conditions, and no effects on the harvest. (3) For the rearing of the larvae at 5th instar, it is most practical to adapt one of the yield methods which can produce good harvest with less labours. That is, the pruning. of the middle branches should be gradually made from a part of the mulberry fold. (4) When it is carried out to pick of the leaves on the branches which was left after the middle-pruning harvest in autumn or late, easy and less labours' harvest method of rough picking may be applied in the both of the mulberry pruned in summer or autumn.

• Journal of Sericultural and Entomological Science
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• v.16 no.1
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• pp.57-65
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• 1974

This study has been carried out to investigate the effect of protein components of a diet on the increasing of larval body weight and diet efficiency, as well as the amylase activity of larval digestive juices during the 5th instar. Defending on the amounts of soybean meal as a protein source, the six different kind of artificial diets containing mulberry leaf powder fed to the larvae. The results obtained may be summarized as follows： 1. As the protein components of the diet were increased, the amount of increased larval body weight was also increased. 2. As the protein components of the diet were increased, both the cocoon weight and cocoon layer weight were also increased. 3. As the protein components of the diet were increased, both the amount of diet digested and coefficient of digestibility were also increased. 4. As the protein components of the diet were increased, the diet efficiency of larvae were also increased. 5. But the experimenters could not observe any correlation between the increase of protein components of a diet and the amylase activity of the digestive juices.

• Journal of Sericultural and Entomological Science
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• v.38 no.1
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• pp.13-18
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• 1996

To secure the genetic resources of silkworm, Bomyx mori, the cDNA library was constructed with mRNA isolated from fifth instar larvae. Titer of the cDNA library was about 1.3 X 106 plaques in total. We presumed that the titer covered all transcripts existed in Bombyx mori. Meanwhile, it is knowen that partial cDNA sequences, Expressed Sequence Tags(ESTs), have a good value for the discovery of novel genes and the elucidation of their structures. For this purpose, partial cDNA sequencing was carried out from randomly selected cDNA clones in the library. Partial cDNA sequences of 37 clones were determined and an average of 212 nucleotides of sequence can be read from the clone. The ESTs were searched in GenBAnk database and fifteen ESTs showed significant similarities to enlisted sequences. They included the genes of storage protein, heat shock protein, actin, catalase and so forth. We presumed that the 22 unmatched ESTs were novel genes.

• International Journal of Industrial Entomology and Biomaterials
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• v.14 no.2
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• pp.127-135
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• 2007

Precocious metamorphosis was induced in two popular bivoltine breeds i.e. YB and $NB_4D_2$ by an imidazole compound having anti-juvenile hormone activity. The chemical was administered by feeding treatment with mulberry leaf to freshly moulted (0-6 hrs) IV instar larvae. The dose of the chemical was found to be breed specific being 650 ppm for YB and 500 ppm for $NB_4D_2$. The chemical caused complete skipping up of the fifth instar larvae which is most susceptible to diseases. But IV instar was somewhat prolonged. As a result the total larval period was reduced by 4-5 days. However, some of the rearing and reeling parameters like cocoon yield, cocoon weight, shell weight, shell %, filament length and fecundity were reduced for that particular generation only. The effective rate of rearing (ERR %) was significantly increased in trimoulters during the most unfavourable August - September seed crop season. Number of cocoons / kg and number of male moth were significantly higher in trimoulters. These may be useful for preparation of $multi{\times}bi$ hybrid seed. Fine denier was also found in trimoulter cocoon which is the cause of getting fine silk filament from trimoulter cocoons. Normal mating behaviour and emergence pattern was recorded in trimoulters. Bivoltine trimoulter males also showed competence for mating with multivoltine females. These results suggest the possibility of getting trimoulter males during hot and humid seasons when rearing of bivoltine is almost impossible particularly in Eastern and North Eastern India.

• Journal of Sericultural and Entomological Science
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• v.34 no.1
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• pp.1-7
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• 1992

For a long-term preservation of silkworm stocks by frozen gonad storage, fundamental topics such as freezing rate and transplanting stage of the gonad, proper cryoprotectant, and super-cooling temperature and freezing point of the freezing medium were examined and following results were obtained. Proper method to anesthetize the ovary-recipient silkworm was to dip the animal to cold water for 10 minutes, and the ovary taken from the 4th instar larvae was more suitable for freezing-preservation than that from the 5th. Concerning the cryoprotectant, glycerol and DMSO were effective to prevent cryoinjury of the ovary, but sorbitol was not. The supercooling temperature and freezing point of the medium to freeze the ovary and testes were checked, and consulting with the results desirable cooling rate was confirmed. On the desirable conditions of transplanting methods, freezing rate and cryoprotectant concentration ect., the next generation was obtained when the females implanted frozen-thawed ovaries mated with normal males, but none of the normal females mated with the males implanted frozen-thawed testes laid fertilized eggs. Now it is needed to improve the connecting ration of the ducts associated with the transplanted testis to those of the hosts.

• Journal of Sericultural and Entomological Science
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• v.52 no.1
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• pp.45-51
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• 2014

A cecropin-A gene was isolated from the immunized larvae of the Japanese oak silkworm, Antheraea yamamai and designed Ay-CecA. The complete Ay-CecA cDNA consists of 419 nucleotides with 195 bp open reading frame encoding a 64 amino acid precursor that contains a putative 22-residue signal peptide, a 4-residue propetide and a 37-residue mature peptide with a theoretical mass of 4046.81. The deduced amino acid sequence of the peptide evidenced a significant degree of identity (62 ~ 78% identity) with other lepidopteran cecropins. Like many insect cecropin, Ay-CecA also harbored a glycine residue for C-terminal amidation at the C-end, which suggests potential amidation. To understand this peptide better, we successfully expressed bioactive recombinant Ay-CecA in Escherichia coli that are highly sensitive to the mature peptide. For this, we fused mature Ay-CecA gene with insoluble protein ketosteroid isomerase (KSI) gene to avoid the cell death during induction. The fusion KSI-CecA protein was expressed as inclusion body. The expressed fusion protein was purified by Ni-NTA immobilized metal affinity chromatography (IMAC), and cleaved by cyanogen bromide (CNBr) to release recombinant Ay-CecA. The purified recombinant Ay-CecA showed considerably antibacterial activity against Gram-negative bacteria, E. cori ML 35, Klebsiella pneumonia and Pseudomonas aeruginosa. Our results proved that this peptide with a potent antibacterial activity may play a role in the immune response of Japanese oak silkworm.

• Journal of Sericultural and Entomological Science
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• v.32 no.1
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• pp.17-30
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• 1990

A 6${\times}$4 top-cross set was made from the ten silkworm parental lines selected by the first principal component scores. They were also analysed for the relationship between the combining ability and the first principal component score. The highest general combining ability effects were detected in the parental lines of Japanese, N39 and chinese, C46, for the most quantitative characters in the study. The first principal component score of factors related to silk productivity in the parents was significantly and positively correlated to the general combining ability of the twelve characters such as cocoon yield, cocoon weight, cocoon shell weight, cocoon shell percentage, duration of the 5th instar larvae, total larval period, length of a bave, weight of a have, non-breaking length of a bave, non-breaking weight of a have, raw silk percentage, and neatness. Similarity distance (D$^2$) was related to the specific combining ability of the characters such as cocoon yield, non-breaking length of a bave, non-breaking weight of a have, non-breaking ratio of a bave, raw silk percentage, neatness. From the results, it is possible to predict the general combining ability effects by the principal component scores for the 12 characters of the parents related to silk productivity.

• Korean journal of applied entomology
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• v.18 no.1 s.38
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• pp.1-10
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• 1979

An inclusion forming virus isolated from a fan webworm, Hyphantria cunea, in 1975 was identified as a nuclear polyhedrosis virus. With the virus isolated in Korea, it was considered that the virus would be one of the valuable microorganism in microbial control. In this connection, 1) the shape and size of the virus for identification, 2) susceptibility of the various instar larvae to the virus, 3) the effects of storage condition on the pathogenicity and the cross infection of the virus to the larvae of Bombyx mori were examined. The results are summarized as follows; 1. The polyhedron was tetrahedron or hexahedron of $2\mu$ in size and the rod-shaped virus particles consisting of $2\~14$ rods in a bundle were $330m{\mu}\times35m{\mu}$ in size. 2. The hexagonal nuclear polyhedra were found only in the nucleus of the midgut cells but were variable in size. 3. The $LD_{50}$ values for the various instar larvae of H. cunea were $8.377\times10^4\;PIBs/ml$ for the second, $4.974\times10^5\;PIBs/ml$ for the fifth instar larvae. The $LT_{50}values$ for $10^6\;PIBs/ml$ were 9.6 days for the second, 11.5 days for the third, 12.0 days for the fourth and 17 days for the fifth instar larvae. 4. The susceptibility of H. cunea to the nuclear polyhedrosis virus was greater in the first generation than in the second generation. 5. The effect of the storage conditions on the pathogenicity of the nuclear polyhedra was less in refrigerator $(5^{\circ}C)$ and in freezing $(-80^{\circ}C)$ than in room temperature $(18.5^{\circ}C)$, especially as air-dried polyhedra than as suspension. The pathogenicity of the polyhedra seemed to decrease by sunlight during storage as cadavers, since rather greater decrease in pathogenicity was found in sunny condition than in shady condition. 6. The effective spray concentration was $6.4\times10^7\;PIBs/ml$ in the field and its $LT_50$ values for the third and the fifth instar larvae were 4.8 days and 14.2 days, respectively. 7. No cross infections were found in the nuclear polyhedrosis virus between H. cunea and B. mori. larvae.

• International Journal of Industrial Entomology and Biomaterials
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• v.3 no.1
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• pp.89-92
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• 2001

The effect of topical application with 5,10 and 15 $\mu$g/ ml androstenedione and methyltesterone to the fifth stadium larvae of the si1kworm,B. mori on fat body glycogen, protein, tota1 lipids, phospholipids, neutral lipids and haemolymph trehalose and protein has been studied. The fat body glycogen increased significantly in all the treated groups except in the 15$\mu$g/ml androstenedione treated group. However the fat body glyco- gen increased significantly in 10 ${\mu}g$/ml methyltesterone treated group. The androstenedione treated groups showed increased haemolymph trehalose but the increase was not significant. However the haemolymph trehalose increased significantly in all the methyltestosterone treated groups. The fat body protein decreased in all the androstenedione and methyltesterone treated groups except 15 ${\mu}g$/ml methyltesterone where the decrease in fat body protein was significant. Whereas that of haemolymph protein significantly decreased in all the groups except in the group treated with 5 ${\mu}g$/ml androstenedione where the decrease was not significant. The total lipids, phospholipids and neutral lipids of the fat body decreased significantly in all the groups treated with androstenedione and methyltestosterone when compared with those of carrier control.