• Proceedings of the Korean Society of Applied Entomolohy Conference
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• 2005.05a
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• pp.189-189
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• 2005

• Proceedings of the Korean Society of Sericultural Science Conference
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• 2002.10a
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• pp.116-116
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• 2002

No Abstract, See Full Text

• Current Research on Agriculture and Life Sciences
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• v.1
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• pp.67-83
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• 1983

The new microsporidia S80 isolated from, Bombyx mori L. in Korea showed ovoid in the morphology of the spores and the size were measured $2.9{\pm}0.28{\mu}$ in length and $1.7{\pm}0.29{\mu}$ width. No other microsporidian spore like this has not been so far isolated from Silkworm. The length of the polar filament extruded in hydrogen peroxide ($H_2O_2$) at $30^{\circ}C$ was $26{\mu}$ of a round cytoplasm on the top. The spores were partly stained with Giemsa, Safranin-O and Gram as the same staining properties as Nosema bombycis, Microsporidia K 79 and other microsporidian spores. The fine structures were observed under scanning eleceron microscope through ultrathin sectioning. The spore wall was composed of three layers ; the thin exospore of an electron dense rippled layer, the thick electron lucent endospore which was thinning considerably at the polar filament insertion point, and the inner limiting membrane. Polar cap present at the sporeapex, with a long polar filament of 12-13 coils, subtending angle of $60^{\circ}$ to spore axis, which is tubular made up of a multilayered and are a benes core, light ring structure enclosing the dance core, the dark ring structure enclosing the inner light ring structure and the other than and light ring structure bounded from cytoplasm. Lamellate polaroplast occupied the anterior part of the spore, and the two neclei with dense nucleoplasm bounded by a double nuclear envelope were cited in the slight downer middle portion of spore. From the characteristics of the shape, size and fine structures, it is certain to reason the Microsporidia S80 belong to the phylum Microspora, class Microspora, order Microsporida, order Microsporida. The shape of two nuclei cited seems to be genus Nosema, but in the classification for the suborder it should be defined wheather pansporoblasts be formed or not and for the genis especial attempts have been made to define the characters which distinguish the disporous genera in the life cycle. Survey through the infection of the bad cocoons during 1980 to 1982 in South Korea the areas contaminated with new microsporidia were revealed 5 provinces of Kyung-Gi, Kang-Won, Chung-Nam and Chun-Nam. Pathological effects inoculated per os at second instar larvae of silkworm, the LD 50 was $7.1{\times}10^7/ml$ as lower pathogenecity than that of Nosema bombycis Naegeli of $1.2{\times}10_7/ml$. While on the other hand the inoculation of the microsporidia at fourth instar larvae lowerd the whole cocoon weight and cocoon shell weight and significant at 1% level. The microsporidia S80 defined it can not be transmitted transovarially from the result of predictive and collective examination of 21 egg batches from the infected female moth.

• International Journal of Industrial Entomology and Biomaterials
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• v.11 no.2
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• pp.81-86
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• 2005

The mode of transmission, effect on fecundity, hatching and tissues specificity of a microsporidian $(Lb_{ms})$ recovered from Lamerin breed of the silkworm Bombyx mori L. was studied and compared with standard strain Nosema bombycis. Peroral inoculation of $Lb_{ms}$ or N. bombycis to zeroday of $4^{th}$ instar larvae of silkworm was the most suitable method for producing information on development of stage specific mortality, pupation and obtaining infected adults for transovarial transmission studies. It was observed that pupal mortality, the percentage of moths emerged and the percentage of moths infected were significantly high in N. bombycis infected batches as compared $(Lb_{ms})$ in all the three tested breeds of the silkworm. However no significant difference was observed in larval mortality. The fecundity and hatchability was not affected significantly in $(Lb_{ms})$ infected adults, however significant reduction in egg production, fecundity, hatchability and increased egg retention was observed in mother moths infected with N. bombycis. The $(Lb_{ms})$ is transmitted both horizontally and vertically at lower rate due to its low rate of proliferation. The trans ovarial transmission of $(Lb_{ms})$ to the $F_1$ progeny generation through eggs averaged only $61.33\pm5.10\%$ whereas N. bombycis was transmitted at $100\%$. The $(Lb_{ms})$ had low oral infectivity and low transovarial transmission in silkworm B. mori.

• Korean Journal of Veterinary Service
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• v.36 no.1
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• pp.37-44
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• 2013

The ecologically and economically important honeybee species are susceptible to infections by various pathogens. This study was investigated to detect infectious pathogens in honeybee colonies reared in eastern Gyeongbuk province by PCR in 2010~2011. A total of 11 infectious pathogens, including 6 viruses, 2 bacteria, 2 fungi, and 1 parasite, were investigated in honeybee colonies suffering from symptoms of sudden collapse, depopulation, or paralysis. The infectious pathogens and infection rates among 24 honeybee colonies detected were as follows: sacbrood virus (66.7%), deformed wing virus (4.2%), black queen cell virus (12.5%), Kashmir bee virus (29.2%), American foulbrood (41.7%), European foulbrood (12.5%), stonebrood (45.8%), chalkbrood (4.2%), and Nosema (33.3%), respectively. Since the coinfection rates of multiple pathogens were detected high in honeybee colonies reared in eastern Gyeongbuk province, large-scale investigation and appropriate control programs need to be established in this region.

• Korean Journal of Veterinary Service
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• v.36 no.2
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• pp.147-150
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• 2013

This study was carried out to investigate the prevalence of honeybee (Apis mellifera) disease in cheonan and asan area. From September to November in 2012, 33 samples were collected from 33 apiculture farms in the regions and reverse transcriptase-polymerase chain reaction (RT-PCR) and polymerase chain reaction (PCR) was conducted. Among 33 samples, prevalence rate was 42% in Sac Brood Virus (SBV), 52% in Nosema, 21% in American foulbrood (AFB), 70% in European foulbrood (EFB), 97% in Stonebrood, 3% in Chalkbrood. The result indicate that stonebrood was most prevalent disease in apiculture farms in cheonan and asan area.

• International Journal of Industrial Entomology and Biomaterials
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• v.12 no.1
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• pp.7-14
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• 2006

Silkworm diseases are better prevented than cured. Disinfection and hygiene are the two important aspects in silkworm rearing to prevent the diseases. Suitable disinfectant is the primary need to disinfect the rearing house, its surroundings and appliances to eliminate the persistent pathogens from the rearing environment. In this direction, Serichlor, a new disinfectant in Indian Sericulture marketed as Serichlor-60 (contains 60,000 ppm of chlorine dioxide) and Serichlor-20 (contains 20,000 ppm of chlorine dioxide) has been evaluated for its germicidal effect against the pathogens of silkworm, viz., spores of Nosema bombycis, Bacillus thuringiensis, polyhedra of BmNPV and conidia of Beauveria bassiana both in vitro and in vivo. Results indicated that high concentration (2,500 ppm of chlorine dioxide) is required to kill all the pathogens at 100% level. The efficacy of the Serichlor was greatly enhanced by the addition of 0.5% slaked lime solution. 500 ppm of chlorine dioxide in 0.5% slaked lime solution was found effective against all the pathogens tested. This concentration of disinfectant was also found effective for disinfection of rearing house, rearing appliances and silkworm egg surface. The disinfectant is stable, non hazardous, least corrosive and most suitable for Indian Sericulture.

• International Journal of Industrial Entomology and Biomaterials
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• v.9 no.2
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• pp.265-267
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• 2004

The silkworm, Bombyx mori L. is prone to infection of various pathogenic organisms. Pebrine, one of the deadliest disease of silkworm caused by highly virulent parasitic microsporidian, Nosema bombycis has been understood since long. Infections of the disease range from chronic to highly virulent and can result in complete lose to the sericulture industry. Several strains and species of microsporidians have since been isolated from the infected silkworms. A new microsporidian spore was isolated from Lamerin breed of the silkworm B. mori have been studied under scanning electron microscope, found to be different in spore size (length 4.36$\pm$0.06 ${\mu}{\textrm}{m}$, width 2.14$\pm$0.01${\mu}{\textrm}{m}$) and shape (ova cylindrical with slight depression) from standard strain N. bombycis (length 3.08$\pm$0.21 ${\mu}{\textrm}{m}$, width 2.01$\pm$0.05 ${\mu}{\textrm}{m}$ and ovidal respectively). In immunological test, the silkworm breed Lamerin isolated micrisporidian spore does not react to different antibody (N. bombycis, M$_{11}$ and M$_{12}$) sensitized latex particle and thus appeared to be a different strain of microsporidian parasitic to the Lamerin breed of the silkworm B. mori.i.i.

• Journal of Apiculture
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• v.33 no.4
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• pp.269-275
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• 2018

Beekeeping status of Apis cerana with emphasis of experiences overcoming sacbrood virus disease are presented. Social bee fauna are rich in Vietnam with 6 honeybee species (Apis laboriosa, Apis dorsata, Apis mellifera, Apis cerana, Apis andrenifomis, Apis florea); 8 stingless bee species (Trigona laeviceps, Trigona ventralis, Trigona pagdeni, Trigona gressitti, Trigona fuscobalteata, Trigona capenteri, Trigona scintillans Trigona iridipenis) and 2 bumble bee species (Bumbus haemorrhoidalis, B. breviceps). All of them are native except A. mellifera which was introduced in1887. These bees are slated for conservation by the Ministry of Agriculture & Rural Development. Honey and other bee products are mainly harvested from 3 species including A. cerana, A. mellifera and A. dorsata. The manageable species (A. cerana and A. mellifera) are increasing in number, reaching about 1,500,000 beehives. Vietnam is the second largest honey exporter in Asia, with a total of about 48,000 tons of honey exported to the international market in 2014. A. cerana plays an important role in poverty alleviation in mountainous and remote areas of Vietnam. Honeybee suffers from various diseases of Sacbrood virus disease (SBV), European foulbrood (EFB), Nosema, and parasitic mites of Tropilaelaps mercedes and Varroa destructor. Most of these diseases can be resolved with biocontrol methods. For the parasitic mites, Vietnamese beekeepers usually apply formic acid.

• International Journal of Industrial Entomology and Biomaterials
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• v.30 no.1
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• pp.6-16
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• 2015

This study established the genetic characterisation of 10 microsporidian isolates infecting non-mulberry silkworms (Antheraea assamensis and Samia cynthia ricini) collected from biogeographical forest locations in the State of Assam, India, using PCR-based markers assays: inter simple sequence repeat (ISSR) and random amplified polymorphic DNA (RAPD). A Nosema type species (NIK-1s_mys) was used as control for comparison. The shape of mature microsporidian spores were observed oval to elongated, measuring 3.80 to $4.90{\mu}m$ in length and 2.60 to $3.05{\mu}m$ in width. Fourteen ISSR primers generated reproducible profiles and yielded 178 fragments, of which 175 were polymorphic (98%), while 16 RAPD primers generated reproducible profiles with 198 amplified fragments displaying 95% of polymorphism. Estimation of genetic distance coefficients based on dice coefficients method and clustering with un-weighted pair group method using arithmetic average (UPGMA) analysis was done to unravel the genetic diversity of microsporidians infecting Indian muga and eri silkworm. The similarity coefficients varied from 0.385 to 0.941 in ISSR and 0.083 to 0.938 in RAPD data. UPGMA analysis generated dendrograms with two microsporidian groups, which appear to be different from each other. Based on Euclidean distance matrix method, 2-dimensional distribution also revealed considerable variability among different identified microsporidians. Clustering of these microsporidian isolates was in accordance with their host and biogeographic origin. Both techniques represent a useful and efficient tool for taxonomical grouping as well as for phylogenetic classification of different microsporidians in general and genotyping of these pathogens in particular.