• International Journal of Industrial Entomology and Biomaterials
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• v.1 no.1
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• pp.9-17
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• 2000

Genetic variation in the domestic silkworm strains (Bombyx mori) and phylogenetic relationships between domestic silkworms and wild silkworms (B. mandarina) were investigated by using a portion of mitochondrial CGI gene sequences. Ten geographic strains of B. mori we sequenced were identical in the 410 bp-section of mitochondrial COI gene. This sequence was also identical to the homologous sequence of the four Gen-Bank-registered strains, but one strain of B. mori differed a single nucleotide (0.2%) from others. MtDNA homogeneity in the B. mori strains appears to be resulted from fixation into the mast frequent mtDNA type during the course of breeding for new strains, in which an extensive indoor rearing and removal of unwanted individuals were accompanied. In the comparisons between domestic and wild silkworms, some wild silkworms were closely related to domestic silkworms (0.2%-1.2% of divergence), but the others were not (2.7%-3.7% of sequence divergence). This result was also reflected in the phylogenetic analyses, showing two independent phylogenetic groups: one including all B. mandarina sequences and the other including both B. mandarina and B. mori sequences. Thus, domestic silkworms may have been derived from the ancestor of B. mandarina, which belongs to this group, alto-ough more extensive study will provide better understanding on this issue.

• International Journal of Industrial Entomology and Biomaterials
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• v.47 no.1
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• pp.51-62
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• 2023

The advantages of silkworms as functional foods are well known and various products are being developed. In general, silkworms sold in the market include silkworm powder (3 days of fifth instars) and SukJam (7 days or more of fifth instars), In other words, product classification is made according to the maturity of the fifth instar silkworms. In this study, we analyzed the gene expression changes in the fifth instar silkworms and attempted to validate the use of deregulated genes in maturity analysis. After rearing BaekokJam, transcriptome analysis was performed on days 1, 3, 5, and 8 days of the fifth instar, and differentially expressed genes showing differences at each period were selected. Of the 31,841 contigs analyzed, 4012 contigs were identified with a log2 fold change of two or more between 5 and 8 days of the fifth instar. RT-PCR was performed for 18 contigs, which showed increased or decreased expression, but in c127159, c97909, c96974, c119920, c42251, and c80216 showed clear differences. To identify SukJam, a combination of the contigs c127159 (180 bp), c97909 (143 bp), and c80216 (120 bp) was amplified. Taken together, these results suggest that the harvest time of silkworms can be determined using gene expression pattern analysis.

• International Journal of Industrial Entomology and Biomaterials
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• v.48 no.1
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• pp.42-47
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• 2024

The value of silkworms as functional health food materials has increased, as has the interest in its disease control for stable production, and in the economic value of entomopathogenic microorganisms. In this study, we isolated and identified disease-causing fungi from white muscardine silkworms, and confirmed whether this strain could produce white muscardine silkworms. For the analysis of the cause of white muscardine disease in the infected silkworms, the fungi and prokaryotes causing the disease were identified, isolated, and identified using metagenome analysis. Metagenomic analysis detected a large amount of the fungus Metarhizium rileyi in silkworms, and a large amount of the bacterium Enterococcus mundtii, which was presumed to be the causative agent of the disease. For accurate identification of the fungi, these were purified by culture medium, and sequencing and phylogenetic tree analyses were performed using an internal transcribed spacer. As a result, M. rileyi, Cladosporium cladosporioides, and C. tenuissimum were identified. In general, M. rileyi is known to form green conidia, but in this study, white-yellow conidia were formed, indicating that the exact causative agent of the fungal disease cannot be estimated by diagnosing the symptoms. Thus, a diagnostic method is necessary for the continuously collection of required pathogens, and identifying their morphological and genetic characteristics.

• Journal of Sericultural and Entomological Science
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• v.16 no.2
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• pp.119-125
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• 1974

When the nomal silkworms reached active time of 3rd instar stage both non-moulting larva and normal silkworms from the same rearing tray were collected and fixed. The silkworms in 4th instar stage whose growth was as dwarfish as those in 1st and 2nd instar stages were also collected and fix with the normal silkworms. Non-moulting larva and normal silkworms were morphologically compared and the examined results from the tissue inspection are summarized as follows： 1. In spite of the fact that the normal silkworms reached the active eating time of 3rd instar stage non-moulting silkworms were dwarfish as if they had been reared for two days. Non-moulting silkworms which were observed at the time of 4th instar stage showed no much difference in their growth. 2. There was the tendency that the exuvial gland as was shown in Fig. 1 and 2 was flat cyslidium of ellipse and its size at thorax was small shile the gland at abdomen was big. 3. The exuvial gland at thorax has been reported to be bigger at thoracic base than at dorsal vessel but according to the present it was examined to be irregular. 4. The size of exuvial gland of silkworms in the active eating stage of 3rd instar was from 151.3${\mu}$ (major axis) to 94.5${\mu}$ (minor axis) at prothorax and from 568.6${\mu}$ (major axis) to 495.1${\mu}$ (minor axis) at 7th abdominal segment. The sire oe exuvial gland of non-moulting silkworm was 57.5${\mu}$ (major axis) to 51.3${\mu}$ (minor axis) at prothorax and from 91.5${\mu}$ (major axis) to 75.5${\mu}$ (minor axis) at 5th abdominal segment (see Fig. 1) 5. When the normal silkworms reached 4th instar active eating stage its exuvial gland was compared to that of dwarfish silkworm. The result was that the size of normal silkworm at prothorax was from 252.2${\mu}$ (major axis) to 131.6${\mu}$ (minor axis) and the size of exuvial gland at 7th abdominal segment was from 691.5${\mu}$ (major axis) to 493.4${\mu}$ (minor axis) while the sire of exuvial gland of non-moulting at prothorax was from 71.4${\mu}$ (major axis) to 61.5${\mu}$ (minor axis) and the size of the non-moulting silkworm's 8th abdominal segment was from 94.6${\mu}$ (major axis) to 71.5${\mu}$ (minor axis) (See Table 2) 6. There was a remarkable difference in the from of exuvial gland of non-moulting silkworm. The size of alveolar of the non-moulting silkworm was many times larger compared to that of normal silkworm 7. There was no great difference between secretory cells of normal and non-moulting silkworms but the granular type exuvial gland was small in sire compared to that of normal silkworm.

• Journal of Sericultural and Entomological Science
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• v.6
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• pp.49-52
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• 1966

It has been reported that the effect of royal jelly on silkworms can be markedly resulted from feeding on royal jelly throughout all the instars. In 1965, I began the experiment in order to know whether it has a practical for rearing, only through feeding silkworms at 1st to 2nd instar, when a comparative little amount of mulberry leaves and labor is needed for rearing. In the method of my experiment, mulberry leaves with different concentration of royal jelly added, 2.5%, 5%, and 10%. respectively, are feeded on silkworms of Sulack ${\times}$ Soyang at 1st and 2nd instar in spring in 1965. However, in the result of the experiment there is not any effect on the survival. the growth speed, the body weight, of the larvae, and the weight of cocoon layer, the cocoon layer ratio, and number of silkworm eggs laid.

• International Journal of Industrial Entomology and Biomaterials
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• v.29 no.2
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• pp.162-168
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• 2014

1-Deoxynojirimycin(1-DNJ or DNJ), a component in silkworm powder, prevents glucose from being absorbed into the bloodstream from the small intestine by inhibiting ${\alpha}$-glucosidase activity. This study compared the functional components of 1-DNJ from various silkworm species using a gene database with those of 1-DNJ produced by silkworms bred through cross-combinations. We utilized comparisons of geographical origins and species of silkworms using a gene database and discovered that 1-DNJ activity was ranked in the following order by species, Japanese (SK-1) > Chinese (C48) > European (Rock191). 1-DNJ constituted varying percentages of silkworm organs in the following order, blood > epithelial tissue > body fat > silk glands. With regard to sex, 1-DNJ, levels were higher in males than females. However, 1-DNJ levels with respect to various genetic traits (blood color, silk color, and egg color) were consistent. In order to study 1-DNJ changes that occurred during cross breeding of the silkworm gene, we bred cross-combinations utilizing SK-1 and C48 silkworms. In conclusion, in order to provide information about the constituents of functional materials contained in silkworm powder, it is imperative that silkworm cross breeding occurs so that the database of functional materials extracted from silkworms will expand.

• Korean Journal of Food Science and Technology
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• v.54 no.1
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• pp.88-93
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• 2022

In this study, silkworms fed Cudrania tricuspidata leaves were powdered, and hydrolytic enzymes, including viscozyme, papain, and flavourzyme, were added to verify the functionality of the different mixtures. In the general component analysis, the C. tricuspidata silkworm (CS) group exhibited higher crude protein and ash content than did the other groups, and the enzyme-treated groups exhibited higher carbohydrate content than the CS group. The DPPH and ABTS radical scavenging activities were significantly higher in the CS treated with viscozyme (CSV) and the CS treated with viscozyme/flavourzyme (CSVF) than in the other groups, with the CSV group showing the highest reducing power. ACE inhibitory activity was significantly higher in the CS treated with visocozyme/papain (CSVP) than in the CS group. In conclusion, rather than using powdered silkworms fed C. tricuspidata leaves, it would be more effective to use hydrolysates from C. tricuspidata silkworms as raw materials for functional foods.

• Journal of Sericultural and Entomological Science
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• v.45 no.2
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• pp.103-107
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• 2003

Entomopathogenic nematodes were isolated through the investigation in soils collected from cultivated and non-cultivated fields using silkworms (Bombyx mori) and Galleria mellonella trap. The detectable rate of entomopathogenic nematodes of silkworms trap was higher than the G. mellonella trap. This study indicates the detection of entomopathogenic nematodes from soils that silkworms are sensitive superior to the G. mellonella to entomopathogenic nematodes. The steinernema, rhabditidae, and diplogatroidae strains successfully cultured on the silkworms host as well as on artificial media. Reproductivity in the living silkworm larva and pupa was 1.5 to 3.5${\times}$ 10$\^$5/ nematodes per host However, G. mellonella could be multiplied less than 5${\times}$l0$\^$5/ nematodes. The dried pupa of the silkworm following mositurize was cultured 0.5 to 2${\times}$10$\^$5/) nematodes per host. The culture methods of the steinernema, rhabditidae, and diplogatroidae strains, using silkworm powder, extracted chicken intestine, and food waste fertilizer could be applicative, but rate of reproduction was low.

• International Journal of Industrial Entomology and Biomaterials
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• v.45 no.1
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• pp.22-28
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• 2022

Silkworms are very sensitive to changes in temperature and humidity, and unless it is a suitable temperature and humidity to grow, the productivity and quality of silkworms are greatly reduced. Therefore, it is very important to manage temperature and humidity for silkworm feeding facilities. In particular, it is essential to install heating facilities in Asian countries with distinct seasonal changes. During the feeding period, many farms manage the temperature and humidity of feeding facilities by installing and using electric heaters inside the facilities. However, it is very difficult to manage the room temperature stably by the heaters. In addition, unlike the temperature inside the facility, silkworms could undergo severe temperature changes as the inside of the rearing tray could not be warm enough. In this study, in order to improve the previous heating method, the new rearing method that directly heats the bottom of the rearing tray was developed. Compared to the previous room-heating system, the novel heater-installed tray (HIT) system significantly reduced the change in temperature during the experimental period. In addition, the number of days of silkworm growth up to harvest was shortened, which was effective in growth performance, and it was also found that silkworms grew more uniformly in HIT system than in previous system. Moreover, as the heater tubes were installed directly under the rearing tray, it quickly dried mulberry leaves and silkworm feces after feeding, and as a result, the environment in the tray was greatly improved with decrease the labor of breeder. In conclusion, these results suggest that the heater-installed rearing tray method greatly improves silkworm quality, increases weight of silkworms, and final profits compared to the previous room heating system with electric heaters.

• International Journal of Industrial Entomology and Biomaterials
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• v.47 no.2
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• pp.79-89
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• 2023

This paper is about the development results of an automatic silkworm breeding system to reduce labor and time by automatically performing the works for silkworm droppings changing and feed its food. It consists of an automatic guided vehicle and a processing unit. The automatic guided vehicle transports a silkworm dropping changing frame mounted on a silkworm tray stand, and the processing unit takes over the dropping changing frame on it, removes excrement contained the droppings changing frame and feeds silkworm food. In the case of the current silkworm farming, because the breeding period for large silkworms (4 to 5 stage) is short to 14 days and the supply of mulberry leaves takes 98% of the total amount of mulberry leaves needed for breeding silkworms at this time, labor concentration is intensive, and all breeding works depends on manpower. Therefore, it was difficult to breed large silkworms on a large scale. Moreover, silkworms are bred by adding Silkworm bed (Seop) and mulberry in the silkworm tray, and their droppings changing is to separate silkworms and excrement by moving silkworm trays one by one, and the production cost increases due to the high-cost manpower for silkworm breeding. To solve this problem, technology for automating silkworm breeding has also been developed. However, there is still a limitation that silkworm feeding and droppings changing works are not suitable for mass breeding because a lot of labor and time are spent depending on manual work. Therefore, a new silkworm breeding system for breeding silkworm automatically is needed and so we developed an Automatic Silkworm Breeding System applying the droppings change frame, the inverting unit, the feeding silkworm food device and automatic guided vehicle.