• International Journal of Industrial Entomology and Biomaterials
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• v.45 no.1
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• pp.29-34
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• 2022

Silkworms have recently attracted attention as healthy functional foods. Different varieties of silkworms have functional differences; thus, there is an emerging need for variety identification. In this study, we sequenced complete mitochondrial genomes (mitogenomes) of ten government-recommended silkworm varieties (BaekHwang, BaekOk, DaeBaek, DaeBak, DaeHwang, GoldenSilk, HanSaeng, JooHwang, KumKang, and KumOk). Comparison of these sequences allowed us to select the single nucleotide polymorphisms (SNPs) in 34 sites that are specific to six silkworm varieties: 13 in DaeBak, 8 in GoldenSilk, 9 in KumKang, 2 in BaekHwang, 1 in BaekOk, and 1 in DaeHwang. Among these each one SNP per variety was amplified by preparing variety-specific primers and then using tetra-primer amplification refractory mutation system PCR (T-ARMS-PCR). As a result, it was possible to identify these six varieties among the ten silkworm varieties, evidencing that SNPs developed from mitogenomes are useful marker for the discrimination of genetically closer silkworm varieties.

• International Journal of Industrial Entomology and Biomaterials
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• v.43 no.2
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• pp.85-93
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• 2021

Silkworm pupae have been utilized as a food source and have high-quality proteins and fatty acids. However, studies on the nutritional composition of pupae according to their variety, developmental stage, and sex have not been conducted. In this study, the nutritional composition of four Korean silk varieties (Baegokjam, BG; Goldensilk, GS; Juhwangjam, JH; and YeonNokjam, YN) were analyzed according to developmental stage and sex. The main ingredient of the pupa was protein, and the protein levels were higher in females than in males. Fat levels were high in males and increased in YN and GS during the late stage but decreased in BG. Fiber content rapidly increased in the late stages, and the lowest content was observed in BG. The pupae contained all essential amino acids, which were detected at higher ratios in females with a high protein content. Fatty acids had a different predominance depending on the variety. Oleic acid level was high in BG, linoleic acid and linolenic acid levels were high in GS, and palmitic acid and stearic acid levels were high in JH. In the mineral analysis, zinc was dominant in BG, whereas calcium and iron levels were relatively low. Zinc level was low in GS, and calcium and magnesium levels were high in JH. Potassium, sodium, magnesium, and phosphorus levels were low in YN. The silkworm pupae showed differences in components according to their variety, sex, and developmental stage; therefore, selecting a variety suitable for its purpose is necessary.

• International Journal of Industrial Entomology and Biomaterials
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• v.32 no.2
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• pp.54-59
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• 2016

All of silkworm varieties reared in farmhouses are first generation hybrids, for the production of these hybrid silkworms precise and labor-saving sex discrimination is necessary. The new variety "Hanbyeolnue" is biparental sex-limited larval marking yellow cocoon variety which was bred from biparental sex-limited strain of Japanese originated Jam 319 and Chinese originated Jam 320. Productivity test of Hanbyeolnue in 2015 showed high healthiness and short larval period. The Hanbyeolnue was evaluated as an excellent variety which can be utilized for special purpose silkworm such as male pupae or Cordyceps production.

• International Journal of Industrial Entomology and Biomaterials
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• v.6 no.2
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• pp.145-149
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• 2003

Seeing inadequate disinfection and unhygenic condition in rearing area, use of disease resistant silkworm variety is the best option. In order to this, an attempt has been made to develop the resistance to Bombyx mori densonucleosis virus (BmDNV-2) into a susceptible silkworm breed Zhenon1 by cross breeding with a resistant silkworm breed SU12 and exposing the subsequent generations to BmDNV-2 followed by the selection of individuals from the surviving batches. After seven generation the evolved DNV-2 resistant strain showed the significantly higher resistance to BmDNV-2 than control Zhenon1. The economic characters of both of the breeds were almost on par.

• International Journal of Industrial Entomology and Biomaterials
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• v.6 no.1
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• pp.57-61
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• 2003

A new silkworm variety, Chugangjam, with a sex-limited larval marking and high silk yielding for summer-autumn rearing season is $F_1$ hybrid between Jam 147, a Japanese race bred from P8503/8453, and Jam 148, a Chinese race from M8306/Jam 130. Jam 147, Japanese parent of the Chugangjam showed a high GCA (general combining ability) in pupation percentage and Jam 148, Chinese parent, showed a high GCA in pupation percentage and single cocoon weight. In the local adaptability test performed at 8 local areas in autumn of 2001, Chugangjam was 5% higher in cocoon yield and 8% in raw silk productivity in the 10,000 of the 3rd molted larvae, respectively, than the check variety Daesungjam.

• International Journal of Industrial Entomology and Biomaterials
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• v.14 no.1
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• pp.63-68
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• 2007

The response of silkworm, Bombyx mori L. to phytoecdysteroid (PE) when administered at different ages of $5^{th}$ instar was studied in the popular bivoltine ($CSR2{\times}CSR4$) and multi${\times}$bivoltine ($PM{\times}CSR2$) silkworm hybrids, reared on the Victory-1 variety of mulberry leaves. PE was administered to $5^{th}$ instar silkworm per os at a rate of $250{\mu}g$ per 100 larvae to different batches of silkworm at 0, 24, 48, 72, 96, 120, 144 hrs and at the onset of cocoon spinning when a few larvae were ripe. The larval and mounting duration, cocoon yield and cocoon characters were influenced by PE. The intensity of influence was dependent on the time of application. The larvae treated at the beginning of the instar, improved the economic traits significantly with a marginal increase in larval duration. In the larvae treated at the middle of the instar, larval duration was shortened remarkably but the economic traits were adversely affected. This particular treatment can become a good management strategy in the case of mulberry leaf shortage or disease incidence. In the larvae treated at the onset of cocoon spinning, the mounting duration was substantially reduced without much effect on the cocoon traits which would be a big benefit in commercial sericulture. The physiological significance of varied response of silkworm to PE administration is discussed.

• Journal of Sericultural and Entomological Science
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• v.51 no.1
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• pp.73-77
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• 2013

Silkworm transgenesis scientists have done some genetic modification work on multivoltine silkworms, but that type of silkworms is less commercial feasible. They are easy to manipulate, because they breed all year round. But the commercial silkworm variety must undergo hydrochloric acid treatment at a high temperature to be artificially hatched. Hydrochloric acid penetrates through the holes in the silkworm eggs, fatally damaging their reproduction. So it had been thought that altering the properties of the commercial silkworm variety would be very difficult. So we have tried to make from diapause to non-diapause eggs using diapauses varieties, 'Backokjam' and 'Jam 124'. At present, our group has establishing the conditions for non-diapause eggs. Oviposited eggs after 40 ~ 60 hours were incubated for 24 hours at $15{\sim}20^{\circ}C$ with dark condition. Non-diapause eggs were completely induced. The hatching rate, molting rate and pupation rate of non-diapause 'Jam 124' and 'Backokjam' eggs showed no differences compared to diapause eggs. When transgenic silkworm using the non-diapause eggs, the hatching rate showed that non-diapause eggs induced from diapause were 40 ~ 70%, diapause eggs treated with artificial incubation were 10 ~ 30%, and polyvoltine strains, HM eggs were 30 ~ 50%. Therefore, we suggest that modification techniques of the commercial silkworm eggs adequate for silkworm transgenesis can be used to develop transgenic silkworms more easily.

• International Journal of Industrial Entomology and Biomaterials
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• v.33 no.1
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• pp.6-14
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• 2016

The mulberry silkworm, Bombyx mori has been one of the most important domestic animals which have provided with silk fibers for weaving fabrics and a food for a protein and lipid source. In addition, various health improvement effects of diverse silkworm larval powders were reported. Recently we found that steamed and freeze-dried mature silkworm larval powder (SMSP) generated using white-jade (also known as Backokjam) silkworm variety extended healthspan and increased resistance to Parkinson's disease in animal models. Because the colors of cocoons in silkworm varieties were caused by altered signal transduction pathways transporting phytochemicals from intestinal lumens to silk glands, we performed the proximate, amino acid, mineral, carbohydrates, fatty acid, and cholesterol composition analyses of SMSPs of 3 silkworm varieties which were weaving light yellow, golden, and red cocoons. Although most of nutrient compositions among 3 SMSPs were similar, there were significant differences in certain amino acids, minerals, and fatty acid compositions. Red silk silkworm (RS)-SMSP had higher contents of crude proteins and total amino acids than other SMSPs. In addition, the ratio of n-3/n-6 unsaturated fatty acids were higher than the other SMSPs. In contrast Golden silk silkworm (GS)-SMSP had higher ratio of potassium/sodium than the other SMSPs. These nutrient analysis results suggested that 3 SMSPs might have common and unique health improvement effects. Thus, further studies in the functionalities of the 3 SMSPs will reveal unknown their health improvements effects.

• International Journal of Industrial Entomology and Biomaterials
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• v.45 no.2
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• pp.99-107
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• 2022

Silkworm pupal extracts (SPE) were prepared in different solvents (water, 30%, 50%, 70%, and 100% ethanol) and their anti-inflammatory effects were evaluated in the RAW264.7 cell line. The SPE composition was initially evaluated by determining the protein content and performing Fourier transform infrared (FTIR) analysis. The protein content of the different SPE ranged from 6.75-130.93 mg/g of extract. FTIR analysis exhibited distinguishable absorption peaks among the extracts and indicated the presence of lipids, proteins, carbohydrates, and nucleic acid moieties. The levels of released nitric oxide (NO) and interleukin-6 (IL-6) expression in lipopolysaccharide (LPS)-induced RAW264.7 cells were only attenuated by 100% ethanolic SPE to 19.44% and 16.77%, respectively. The other solvent extracts were ineffective. Hence, further studies were conducted with 100% ethanolic SPE from three distinct stages of male and female silkworm pupae belonging to four silkworm varieties (Baegokjam; B, GoldenSilk; G, Juhwangjam; J, and YeonNokjam; Y). The best reduction in NO release and interleukin-1β (IL-1β) expression levels was achieved by the SPE of early female pupae belonging to the Baegokjam variety (32.72%) and those of early female pupae belonging to the Baegokjam and GoldenSilk (59.93%) varieties, respectively. The best reduction in IL-6 expression by 49.70% was achieved by SPE from female pupae of the mid-pupal stage belonging to the Baegokjam variety.

• International Journal of Industrial Entomology and Biomaterials
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• v.47 no.1
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• pp.1-11
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• 2023

The Indian golden muga silkworm, Antheraea assamensis Helfer is an economically important wild silkworm endemic to Northeastern part of India. In recent years, climate change has posed a threat to muga silk production due to the requirement that larvae be reared outdoors. Since the muga silkworm larvae are exposed to the vagaries of nature, the changing climate has increased the incidence of microbial diseases in the rearing fields. Accurate diagnosis of the disease causing pathogens and its associated epidemiology are prerequisites to manage the diseases in the rearing field. Although conventional microbial culturing methods are widely used to identify pathogenic bacteria, they would not provide meaningful information on a wide variety of silkworm pathogens. The information on use of molecular diagnostic tools in detection of microbial pathogens of wild silk moths is very limited. A wide range of molecular and immunodiagnostic techniques including denaturing gradient gel electrophoresis (DGGE), random amplified polymorphism (RAPD), 16S rRNA/ITSA gene sequencing, multiplex polymerase chain reaction (M-PCR), fluorescence in situ hybridization (FISH), immunofluorescence, and repetitive-element PCR (Rep-PCR), have been used for detecting and characterizing the pathogens of insects with economic significance. Nevertheless, the application of these molecular tools for detecting and typing entomopathogens in surveillance studies of muga silkworm rearing is very limited. Here, we discuss the possible application of these molecular techniques, their advantages and major limitations. These methods show promise in better management of diseases in muga ecosystem.