• International Journal of Industrial Entomology and Biomaterials
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• v.4 no.2
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• pp.117-120
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• 2002

Scelionid eggParasitoids Play an important role in biological control of some economically important pentatomids. Stink bug (Canthecona furcellatta Wolff,) is an important predator of Tasar silkworm larvae (Antheraea mylitta D.) and causes 30-40 percent loss in tasar silk industry. Psix striaticeps (Scelionid: Hymenoptera) has been found to be an important egg parasitoid. The parasitization potential of f striaticeps is mere than 60 percent and the sex ratio is female oriented. Studies indicate that the maintenance of existing scelionid population by avoiding harmful practices and the augmentation of scelionids either directly releasing them in the field or by indirectly making the field environment more favorable for them is an important aspect to control the pentatomid population in sericulture. Female bias sex ratio is advantageous to increase the parasitoid population in the field. 24-hour-old egg of stink bug and one-day old parasitoid is suitable for producing maximum progeny. 1 : 30 of parasitoid: host ratio is needed to regulate the estimated population in silkworm rearing field.

• International Journal of Industrial Entomology and Biomaterials
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• v.18 no.1
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• pp.1-7
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• 2009

Quality of seed in the mulberry silkworm, Bombyx mori (L.) is determined by many important factors, wherein unfertilized eggs play an important role. Unfertilization of eggs are caused by several reasons such as, abnormality in the sexual organs of the male and female, abnormal development of the micropylar end of the egg, unfavorable environmental conditions during spinning, cocoon preservation, imperfect handling of moths, mating, ovipostion, cold storing of pupae / moths and indiscriminate use of male moths etc. Though the presence of unfertilized eggs would in no way affect the fertilized ones and their quality directly, the frequency of their occurrence underrates the quality and brings down the hatching percentage. Lower the occurrence of unfertilized eggs, higher is the rating of seed quality. Of the various intrinsic and extrinsic factors and events involved in egg deposition of an adult silk moth, mating is an instinct and a biological obligation for the ultimate perpetuation of the species and a must to provide stimulus for oogenesis and bring about biochemical changes in the spermatophore of the silkworm in order to ensure the presence of sufficient number of normal sperms and testicular fluid in the female reproductive organ, activating ovulation and accelerating oviposition behavior and egg deposition. An attempt has been made in this article to briefly elucidate the characteristics of unfertilized eggs, causes of their occurrence and its impact as well as the significance in silkworm seed production.

• International Journal of Industrial Entomology and Biomaterials
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• v.25 no.2
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• pp.171-174
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• 2012

In order to study the feasibility of utilizing bivoltine foundation cross (FC2) males of the silkworm as male components with Pure Mysore (PM), six foundation crosses viz,CSR2 x CSR27, CSR27 x CSR2, CSR27 x CSR50, CSR50 x CSR27, CSR2 x CSR50 and CSR50 x CSR2 along with CSR2 pure breed were assessed for performance of parental crop,grainage, rearing and reeling performance. The foundation crosses exhibited better performance than CSR2 as a parental crop and male component which resulted in higher egg recovery. Though there was not much difference between PM crossed with FC2 and CSR2 males pertaining to important bioassay parameters, PM x CSR2 exhibited superiority in reeling traits particularly with reelability and raw silk %. This study reveals that FC2 seed cocoons can be utilized during exigency when there is a dearth for CSR2 seed cocoons but not regularly.

• International Journal of Industrial Entomology and Biomaterials
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• v.39 no.1
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• pp.14-21
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• 2019

Genome editing by CRISPR/Cas9, a third-generation gene scissor in molecular breeding at the genome level, is attracting much attention as one of the breeding techniques of the future. In this study, genetic and phenotypic analysis was used to examine the responsiveness of the Bakokjam variety of the silkworm Bombyx mori to molecular breeding using CRISPR/Cas9 in editing the white egg 2 (w-2) gene. The nucleotide sequence of the w-2 gene was analyzed and three different guide RNAs (gRNA) were prepared. The synthesized gRNA was combined with Cas9 protein and then analyzed by T7 endonuclease I after introduction into the Bm-N silkworm cell line. To edit the silkworm gene, W1N and W2P gRNA and Cas9 complexes were microinjected into silkworm embryos. Based on the results of microinjection, the hatching rate was 16-24% and the incidence of mutation was 33-37%. The gene mutation was verified in the heterozygous F1 generation, but no phenotypic change was observed. In F2 homozygotes generated by F1 self-crosses, a mutant phenotype was observed. These results suggest that silkworm molecular breeding using the CRISPR/Cas9 system is possible and will be a very effective way to shorten the time required than the traditional breeding process.

• International Journal of Industrial Entomology and Biomaterials
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• v.8 no.2
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• pp.217-219
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• 2004

Stimulation of fecundity following female antennal amputation has been reported for the first time in silkworm. Antennal amputation caused significant increase in fecundity in two newly evolved multivoltine silkworm breeds viz., BL 67 and 96A. This study indicated better chances for increasing egg yield and the increase in fecundity may be attributed to the action of some neurohormones. Significance of antennal amputation in silkworm has been discussed.

• Journal of Sericultural and Entomological Science
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• v.42 no.1
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• pp.10-13
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• 2000

The objective of this research was to characterize of the silkworm that might be recognized to the Korean native strains. The eleven strains of Korean race used in this study, which is cultured in Korea and Japan seri-cultural research organs. Most of Korean varieties were three molting and univoltine, comparatively longer larval duration than the trimolter general. The egg characters of varieties showed short-eliptic shape and dark brown egg color except for a few varieties which shows greenish dark brown. Also, most of varieties were showed the plain(p) and moricaud( $p_{M}$) in larval markings. Moric marking of the varieties also consist of innumerable dark grayish brown lines and dots, though somewhat darker and lighter than that of the wild silkworm, Bombyx mandarina. Cocoon characters variations of varieties were seen in the size, color and shape. 8 varieties were colored cocoon, i.e., yellow, greenish yellow and light green etc., the others were white cocon. The shape of cocons were consisted of constricted shallowly in the middle and attenuated at one or both ends of cocoon, i.e., spindle. The results of this study is sufficient evidence that Korean strains were shown as the one of regional origin strain of domesticated silkworm such as the Chinese and Japanese etc.c.

• Journal of Sericultural and Entomological Science
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• v.17 no.1
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• pp.35-39
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• 1975

The acid treatment hatching method has been used practically for about 60 years and a number of investigators have studied about the artificial hatching for silkworm e99s, but the basic theory about the acid treatment hatching is not clarified yet. It is no exaggeration to say that the accidents of non hatching is continued ceaselessly in the silkworm egg by hydrochloric acid treatment. It is believed that the accident is due to the adulterants in HCl lather than inattention of acid treatment. Therefore, the authors mixed hydrochloric acid (analytical grade) with or added it to chemical ingredients which are possible to be included in the process of hydrochloric acid production, and treated it to summer and fall silkworm egg. The metalic adulterants such as iron, mercury, lead and arsenic are appeared not to be worried, but damage of SO$_3$ and free chlorine is seemed to lie considerable. Therefore, before acid treatment for hatching hydrochloric acid was warmed to 50$^{\circ}C$ with shaking to evaporate several injurious gases, by whick the damage due to use of hydrochloric acid for acid treatment hatching is prevented considerably. In conclusion, it is recommended to pretest bioassay with every HCl samples before artificial hatching of silkworm egg.

• Toxicological Research
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• v.16 no.1
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• pp.53-57
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• 2000

A mutagenicity testing system using a specific locus mutation of Bombyx mori was introduced from National Institute of Genetics in Japan. In the system, mutagenicity could be detected by the egg color manifested by the pe and/or re genes, which is a kind of recessive visible mutation of the insect. The efficiency to detect mutagenicity of the system was examined and improved. To promote the sensitivity of the system to mutagens, eight varieties of Bombyx mori were tested for their sensitivity to two mutagens, EMS and MMC. Two varieties of the silkworm, N12 and C5, were finally selected as the most sensitive ones. The most sensitive development stage of the silkworm to mutagens was mid and late pupal stages for female and male, respectively. The system will be applied to test unknown mutagens after some more detail examination about its sensitivity.

• Journal of Sericultural and Entomological Science
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• v.13 no.2
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• pp.119-122
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• 1971

The following results were obtained through the experiments and study of fertility for silkworm eggs in vagina, oviduct, and ovarial base. The sample eggs were collected after leaving silkworm moth for one week from the date of treatment was given to oviporm orifice of the silkworm moth by heated needle in order to discontinue laying eggs. Those sample silkworm moths were divided into two groups. The first group was under the condition of immediately after the couplation and the second group was under the condition of after the laying eggs in some extend, and both of them were completed couplation. The sample eggs were screened in order to confirm the degree of color which normally be observed as very characteristic during hibernating. 1. About 5% of silkworm out of the total sample were identified as having 1-2 eggs. (See table 1). But, the charasteristic colour of hibernating egg was not observed. The colour was not much different as that of eggs in ovarian duct. 2. Immediately after the couplation, the eggs were not found in vagina under the condition of immediately after the couplation. 3. About 10% of the sample under the condition of after laying eggs in some extend were found having eggs in vagina or oviduct. 4. About 2% of the sample silkworm moth under the condition of immediately after the couplation were found having I fertilized egg in oviduct. 5. No fertilized egg was found in ovarian tube. It seemed that sperm did not enter ovarian tube. 6. Almost the entire eggs were found in ovarian tube under the condition of immediately after the couplation. But, eggs under the condition of after laying eggs in some extend were found around oviduct and vagina due to the continuous movement of silkworm eggs towards oviporus orifice. 7. Sperm is mainly found around seminal receptacle and vagina, and sperm goes into micropyle together with silkworm eggs which were moving towards oviduct.

• Journal of Sericultural and Entomological Science
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• v.16 no.2
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• pp.111-117
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• 1974

The electron micrographs of the larval brain of the silkworm. Bembyx mori. show that median neurosecretory cell of diapause-egg producer may participate in the production of lipo-granules and that of non-diapause egg producer may do in the production of electron-translucent vesicles. It was found that ribosome-like particles of diapause-egg producer gradually developed into highly dense particles and came into line along the smooth-surfaced endoplasmic reticulum. They finally became lipo-granules.