• Journal of Sericultural and Entomological Science
• /
• v.4
• /
• pp.97-101
• /
• 1965

This work was carried out to investigate the relation between the fat content and the metamorphosis as the silkworms grew. The results obtained are as follows: 1. The content, of which the dry matter had been 24% at the stage of newly hatched silkworms, were gradually decreased by feeding on, but suddenly increased to the 28.5% at the mature stage. Those decreased slightly from pupation to just before the moths, and again increased to the 32% of the dry matter when became the moths. 2. The content, of which the fat had been 16.2%, however, decreased as the silkworms grew. The fat content increased little by little from the first feeding to the vigorous eating, but the matured worm contained only 15.7% of the fat. 3. The fat content of both male and female showed an increase to 23.5% and 35.7%, respectively. After that, the contents of it decreased to 12% and suddenly increased to 26% just before the moth in female. In male the content of fat showed a slight increase till before the moth, and after moth became, it were 42.5%.

• Journal of Sericultural and Entomological Science
• /
• v.22 no.2
• /
• pp.8-12
• /
• 1981

Practical application of silkworm artificial diet is very desirable to save labour in sericultural industry as the problem of labour shortage is becoming serious in Korea. However, silkworms reared on the artificial diet are more susceptible to viruses than those reared on mulberry leaves because of the lower anti-viral activity of gut juice of silkworms grown on artificial diet compared with that of silkworms grown on mulberry leaves. In this study, authors investigated the varietal difference of silkworm larvae, Bombyx mori L., reared on artificial diet which contained 20 percent of dried mulberry powder, in the susceptibility to nuclear polyhedrosis virus (NPV). The results showed that there is no difference in susceptibility to NPV among tested varieties when high concentration of NPV was admitted to silkworm larvae, but varietal difference appeared in lower concentration admitted. Among 7 hybrids tested, Hansaeng 1${\times}$Hansaeng 2 was most resistant to NPV with an $LC_{50}$ of 2.7${\times}$10$\^$6/ and Jam 111${\times}$Jam 112 was also more resistant comparatively than other hybrids.

• Human Ecology Research
• /
• v.56 no.4
• /
• pp.407-416
• /
• 2018

This study investigated the characteristics and changes of Jeongbang-village silk culture Jeollanam-do Province during Japanese Colonial Rule with a focus in on Gokseong-gun & Damyang-gun Jeongbang-village. The results of the study are as follows. First, after Japanese occupation, it changed from a traditional silkworm species, the Joseon Silkworms and the mulberry tree to an improved Japanese species. Japan established a silk spinning mill called Jongyeon Textile factory in Gwangju and Jeongbang Village was formed in poor rural areas. Second, the way of village management consisted of buying a large number of land for mulberry plans and creating mulberry fields as a cheap way to utilize the labor force for women and men in rural areas. Third, since the end of the Japanese colonial era, mulberry fields in Jeongbang villages which the Japanese left, were sold at a cheap price to Koreans. After the Korean War, the Korean government's efforts to modernize the silkworm industry resulted in a continuous plan to increase the number of silkworms. The impact of government policies has also increased the production of silkworms in these areas. However, since the early 1980s, Korean companies have been affected by Japanese economic policies and dumping by China that has resulted in in a sharp decline in their production. In the case of Gokseong-gun and Damyang, the production of silk products was halted and switched to other crops in the early 1990s when the farming industry began to decline.

• International Journal of Industrial Entomology and Biomaterials
• /
• v.4 no.2
• /
• pp.83-91
• /
• 2002

The protection of silkworm and its host plants from various kinds of pests parasite and predator is a chronic problem in sericulture. Silkworms and its primary food plants are heavily damaged by large number of pest. The major pests of primary tasar food plants (Terminalia arjuna and Terminalia tomentosa) are the gall insect (Trioza fletcheri minor). Various species of aphids (Eutrichosiphum sp.) have been recorded to damage oak tasar food plants whereas muga silkworm host plants (Machilus bombycina and Litsaea polyantha) are generally attacked by stem bores (Zeuzera multistrigata). Castor (Ricinus communis) is one of the primary host plant of eri silkworm and extensive damage is caused by the castor white fly (Trialeurodes ricini). Insects pests are major enemies of silkworms. Parasites (Blepharipa zebina, Exorista bombycis, Apateles glomeratus), predators (Canthecona furcellata, Sycanus collaris, Hierodulla bipapilla), wasps (Vespa orientalix) and ants (Oecophylla smargdina) continues to cause damage to silk industry. It is estimated that the losses due to parasites and predators are to an extent of 15-20 percent and varies from crop to crop. The complexities in the behaviour and life cycle of pest population existing in semi ecosystem warrant a special attention for their effective management specially in changing scenario for our modern sericulture. Though use of synthetic insecticides has provided us with effective control of almost all major pests and predators, yet their undesirable side effects limit their continued use. Biological control is one of the most important method which can be used to control the pests, parasites and predators population in sericulture. Various potential parasitoids, which can be utilized as an agent of biological control in sericulture have been screened. The natural enemies of the uzi fly (E. bombycis and B. zebina ) are already present in the nature. Nesolynx thymus, Trichria sp., Splangia endius, Dirhinus sp., Trichopria sp., Trichomalopsis apanteloctena and Pediobius sp. are the major parasitoids effective against uzi fly pupa. The scelionid Psix striaticeps and Trissolcus sp. are the Potential egg Parasitoids against stink bug (Canthecona furcellata). Various other native natural potential parasitoids have been screened and suitable strategies have been developed to check the population of pest insect in sericulture.

• Journal of Sericultural and Entomological Science
• /
• v.14 no.1
• /
• pp.15-24
• /
• 1972

During the autumn-rearing season of 1971, at the silkworm rearing house at the college of agriculture, Seoul national university in Korea, the authors carried out a series of experiments (1) on the susceptibility of four important silkworm pathogens (Aspergillus flavus, Bacillus thuringiensis, Aspergillus oryzae, and Isaria farinosa) to Halamid (Tosylchloramide Sodium), (2) on the acute toxicity of Halamid to silkworm larvae at every instar, (3) on the inhibiting effect of Halamid to the attack of two silkworm infections, fungal muscardine and viral jundice, and the chronic toxicity of Halamid to silkworm larvae, and (4) on the yield and quality of the raw silk harvested from the Halamid treated silkworms. As the results of the experiments the authors found that Halamid could be applied usefully to silk worm rearing industry as an effective disinfectant for both silkworms themselves and their envir onmental articles, rearing houses and tools, also that Halamid exerts its disinfectant effect most efficiently as a disinfectant for silkworms when sprayed in 2% or 3% aqueous solution every second day throughout all tile instars of larval stage.

• Journal of Sericultural and Entomological Science
• /
• v.48 no.1
• /
• pp.16-20
• /
• 2006

To shorten the labor cost for the production of the fungus, Paecilomyces tenuipies, uncocooning mutant hybrid silkworms as a host was used. The yield of P. tenuipies was reduced when Nd (uncocooning mutant) was used as a host because Nd was smaller than the hybrid Baegokjam that has been used as a typical host. To increase the host weight, Nd was crossed with Jam l23 or Jam 124, and resulted in not only greater weighter but also higher yield of P. tenuipies. The optimum temperature for rearing Nd hybrid silkworms was $3^{\circ}C$ higher than standard temperature of rearing silkworms to increase the naked pupation rate. The optimum time for the infection of P. tenuipies was 12 h at $28.5^{\circ}C$ and 95% R.H., when $1{\times}10^7spores/ml$ of P. tenuipies were sprayed on the surface of the silkworm. The conditions were applicable to both spring-rearing and autumn-rearing.

• Journal of Sericultural and Entomological Science
• /
• v.15 no.1
• /
• pp.15-25
• /
• 1973

The author studied the applicability of Furazolidone to the silkworm rearing industry as a useful remedy for certain silkworm diseases, at the silkworm rearing house of the college of agriculture, Seoul national university, during both the spring and the autumn silkworm rearing season of 1972. Discovering the fact that Furazolidone, when put on the mulberry leaves in a powdered form, is eaten along with the leaves by silkworms and thus the systematic administration of Furazolidone to silkworms is possible, the experimenter carried on a series of experiments (1. determining the in vitro antibacterial activity of Furazolidone to four pathogens of silkworm diseases-Bacillus thuringiensis, Aspergillus oryzae, Aspergillus flavus, and Isaria farinosa, 2. observing the prophylactic and therapeutic effect of Furazolidone against the experimental flacherie caused by inoculation of B. thuringiensis, and 3. examining the toxicity of Furazolidone to silkworm larvae). As the results of the experiments the investigator found out the fundamental fact that Furazolidone exerts a good prophylactic and therapeutic effect against flacherie which is the most common and important silkworm disease: Furazolidone, in in vitro test, inhibited completely the growth of B. thuringiensis, the pathogen of bacterial flacherie, at the concentration of 1 ${\mu}$g/mι. with the tube method and at the concentration of 5 ${\mu}$g/mι. with the plate method, and the drug showed an excellent prophylactic effect and a considerably good therapeutic effect, depending on the time of administration, on the 5th instar silkworms inoculated B. thuringiensis, at the tentative dose of 150mg. per 10 silkworms administered once a day for 2 days. For the practical administration of Furazolidone against flacherie, the dose, the time and duration of administration, and the form of preparation, will be investigated more closely.

• International Journal of Industrial Entomology and Biomaterials
• /
• v.22 no.1
• /
• pp.1-4
• /
• 2011

This study was conducted to test the use of colored cocoon silkworm, Golden Silk, as a host for the fruiting body production of Cordyceps mushroom. Golden Silk variety had a shorter larval period than Yangwonjam at $25.3^{\circ}C$ and 78.5% RH: The average larval period of the Golden Silk was 24 days and 7 hr, and that of the Yangwonjam was 24 days and 15 hr. In the infection test of I. tenuipes on silkworm, the larval period of normal silkworms was longer than the silkworms inoculated with I. tenuipes in both Golden Silk and Yangwonjam. The pupae survival percentage of Golden Silk was 94.4%, whereas it was 91.9% in Yangwonjam. Golden Silk had a higher pupation rate than Yangwonjam. The pupation rate of normal silkworms was about 5% higher than that of silkworms inoculated with I. tenuipes. Infection rate of I. tenuipes into larvae of 5th instar newly exuviated silkworm was 93.8% in Golden Silk, and 96.9% in Yangwonjam. Synnemata production of I. tenuipes was better in Yangwonjam with an incidence rate of 99.8% than Golden Silk with 98.6%. The average synnemata weight of Golden Silk was 1.12 g and that of Yangwonjam 1.29 g. Golden Silk had a lower synnemata weight than Yangwonjam. But no significant difference was observed in synnemata weight varieties. The synnemata of I. tenuipes produced on pupae were white or milky-white in color, and similar in shape and color to wild synnemata collected in Korea.

• Journal of agriculture & life science
• /
• v.45 no.6
• /
• pp.115-124
• /
• 2011

This study was conducted to find a useful alternative herbivore system with which to study the effects of ultraviolet exposure on the pathogenicity and survival of Korean isolated entomopathogenic nematodes (Heterorhabditis sp. 202 strain, Heterorhabditis sp. Gyeongsan strain, Steinernema sp. 223 strain, S. carpocapsae Pocheon strain, S. glaseri Dongrae strain and S. longicaudum Nonsan strain). Pathogenicity of entomopathogenic nematodes against silkworm, Bombyx mori, differed depending on the nematode species and strain and instar of silkworm challenged. Steinernematidae were relatively more pathogenic to the 5th instar silkworms, whereas Heterorhabditidae were more pathogenic to the 1st instars. UV-C exposure was harmful to entomopathogenic nematodes. All nematodes were killed within 60 minutes of exposure of UV-C, and after 10 min of exposure they caused only 6.7% corrected mortality of silkworms. Silkworms were not infected when they were fed S. carpocapsae Pocheon strain treated mulberry leaves which were exposed to UV intensity of about $2.3mW/cm^2$ for 4 hours in the field. Pathogenicity of S. carpocapsae was not significantly reduced after 1 hour of exposure to $4.0mW/cm^2$ UV intensity on the mulberry leaves against silkworms.

• Korean journal of applied entomology
• /
• v.61 no.4
• /
• pp.675-688
• /
• 2022

Produced by steaming mature silkworms, HongJam is a natural functional food with various health-promoting effects. The current standard HongJam production protocol involves freezing and freeze-drying steamed mature silkworms for convenient long-term storage and/or selling it to customers. However, freeze-drying HongJam requires a range of processes and costs, which have contributed to its high resale value. In this study, we found that the cost of manufacturing HongJam powder could be reduced by homogenizing steamed mature silkworms using a high-speed blender and digital homogenizer, followed by spray drying. After the homogenized HongJam solution was digested by directly adding food-graded proteases, food-graded protease-digested homogenized HongJam solution was spray-dried. Food-graded digested protease or non-digested homogenized HongJam solutions could be used to produce food for special medical use for patients with general or specific diseases. This more efficient HongJam processing protocol proposed in this study can facilitate the development of sericulture farms and related industries by reducing the production costs of HongJam and its associated products.