• 한국잠사곤충학회지
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• 제39권2호
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• pp.146-153
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• 1997

The microsporidian infection with Nosema bombycis, reconfirmed its high virulence and transovarial tranmissibility, however, the characteristic symptom of the spots like pepper grains on the diseased larval skin was no more recognized by present varieties of the silkworm. Transovarial transmission rate detected from moth was above 90% in dead eggs or dead larvae in the rearing by mulberry leaves, 80% in the newly hatched larvae starved to death. Transovarially transmitted N. bombycis was easily observed from dead eggs and larvae, and were suggested an individual inspection of a few of dead eggs for detection of the pathogenic spores. The progeny population provided indicative factors on the sampling of predictive and corrective inspection. The higher concentration of N. bombycis spores included in the hindabdormal part of infected moth, applicative on the simple method of indivisual moth inspection. For the predictive inspection of growned 5th-instar larvae, N. bombycis infection was detectable without microscopic observation by the unique symptom of turbid milky-white spots on the silk gland. Inspection of the meconia artificially discharged from silkworm moth, was also succesful of microscopic observation before crossing, without killing or homogenize the moths. The results provided a basis of rational methods for the inspection of N. bombycis infection of the silkworm.

• 한국잠사곤충학회지
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• 제39권2호
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• pp.154-160
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• 1997

Present experiment designed for the review of theoretical basis for the inspection system of infected insects by Nosema bombycis. A microporidian N. bombycis, known as the high virulence, produced at the average of 7$\times$108 spores per female moth of the silkworm, Bombyx mori, enabled transovarial tranmission. Detectability of N. bombycis spores in the mass inspection was varied by dillution level, the higher limit of dillution with healthy moths was 1:140 for 100% detection, 1:160 for 99.5%, 1:200 for 99.0%. For an efficient inspection under the microscopic observation (600$\times$), the lower limit of spore concentration was determined as 1, 000, 000 spores/ml, 60-80 moths could be applicable for a maximum sample unit of a lot. Following the present inspection unit conditioned 35 to 40 moths for a lot. N. bombycis spores were easily detectable from the preparation of crude homogenate with 2% KOH, even the step of contrifuge was omitted. The results suggested a new basis of rational mass inspection system of silkworm female moths to save the facilities, labor, and time.

• 한국잠사곤충학회지
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• 제38권1호
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• pp.48-52
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• 1996

Nosema bombycis의 경란전염은 집누에의 경우 난내 및 난면의 두가지 경로가 존재하는 것으로 입증되었다. 난내에서 병원체가 존재하는 부위가 난각 조직을 제외한 장액막, 난황, 배자 등이였다. 난내에 침입한 병원체는 난의 발육과 동조적으로 발육 증식하므로써 오랜 시일이 경과하여도 불활화 되지 않는 동시에 감염난의 치사를 줄일 수 있으며, 병원체가 안전하고 확실하게 차대의 유충으로 전달되므로난내경로는 경난전염율이 높은 것으로 밝혀졌다. 난면경로는 감염 모체의 아충에 의한 난 표면의 오염이 주 원인으로서, N. bombycis 감염아는 100%가 아뇨에 병원체가 검출되며, 4.6$\pm$0.24)X106/ml의 포자를 함유하는 것으로 밝혀졌다. 난 표면에 부착된 병원포자는 비휴면란에 도말하였을 때, 10일 정도 경과 후 부화된 유충의 54.5%가 감염되었으나, 월년 보호하거나 침산한 경우 차대잠의 감염은 인정되지 않았다. 따라서, 집누에 월년란의 경우 경란전염에 의한 질병의 만연에는 난내경로가 주요한 것으로 결론지었다.

• International Journal of Industrial Entomology and Biomaterials
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• 제11권2호
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• pp.107-111
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• 2005

Impact of microsporidian infection and season on reproductive potential of Bombyx mori L. was investigated in the laboratory. Microsporidian infection significantly (P<0.01) reduced fecundity and hatching and increased sterility and mortality of eggs. Among the microsporidia, Nosema sp. 2 infected silkworm produced eggs with least fecundity and hatching percent as well as highest dead and sterile eggs followed by Nosema sp. 1 and N. bombycis. Microsporidia, in general, significantly reduced fecundity and hatching percent of eggs and increased number of dead and sterile eggs in all the three seasons except N. bombycis in July - August (S3) and Nosema sp. 2 in January February (S1). Since, seed production is the anchor sheet of mulberry sericulture, coefficient of egg lying is considered as an important aspect and the industry quite often facing shortage of disease free layings. The present study indicates that B. mori is more susceptible to microsporidia during S2 followed by S3 and S1 and Nosema sp2. is most virulent followed by Nosema spl. and N. bombycis.

• 한국잠사곤충학회지
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• 제36권1호
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• pp.69-75
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• 1994

경란전염은 숙주의 생식소 감염이 전제되므로 Nosema bombycis 감염 집누에를 대상으로 생식소의 발육에 수반된 란 및 정자 형성과 경란전염의 성립에 미치는 영향을 해부 및 조직병리학적 측면에서 구명하였다. 생식소의 감염경로는 도관을 통하지않고 체공에 접한 주변부의 피막조직이 먼저 감염된후 난소내부로 병세가 확산되었고, 감염시기는 다른 조직에 비하여 지연되므로 중증인 개체에 한하여 생식소의 감염은 인정되었으나 란 및 정자 형성이 저해되고 숙주는 성충화 전에 치사하였다. 생식능을 보유한 경증의 감염개체에서는 난소의 감염이 번데기 초기까지 인정되지 않았으나 경란전달은 가능하였다. 병원포자는 자력으로 이동할 수 없으며 성숙란에 대한 침입 가능성도 부정적인 것으로 판단되었으므로, 경란전염이 성립되는 란의 감염시기는 난소소관이 체공에 직접 노출되는 번데기 시기의 2~3일경 부터 난소난의 난각형성이 개시되기 전인 제10 발육단계까지의 기간이 될 것으로 추정되었다.

• International Journal of Industrial Entomology and Biomaterials
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• 제18권2호
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• pp.83-89
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• 2009

Multiplication and spore production of three microsporidia(Nosema bombycis, Nosema sp. 1 and Nosema sp. 2) in selected tissues of pupa and adult of silkworm, Bombyx mori L. were studied in two seasons (SI, SII) with distinct temperature (SI: $20.1{\pm}0.8^{\circ}C$ and SII: $25.1{\pm}0.7^{\circ}C$) regimes. Multiplication of the microsporidia followed a logistic pattern with a lag phase, an exponential phase and a stationary phase. In SII, spore production was significantly (P<0.01) higher in various tissues. Highest spore production was observed 30 days post inoculation (p.i.) in SI and in SII, it was $21{\sim}23$ days p.i. Spore production was significantly (P<0.01) higher in the gut tissues than other tissues. Nosema sp. 2 registered significantly (P<0.01) higher spore production in both the seasons compared to Nosema bombycis and Nosema sp. 1. Results indicate that the multiplication and spore production of microsporidia are tissue specific and extremely sensitive to the temperature at which the host is reared. Through this study, the precise day that the spore numbers of the microsporidia are maximized can be predicted in both pupa and adult in case the infection is initiated in the first instar.

• International Journal of Industrial Entomology and Biomaterials
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• 제17권1호
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• pp.157-163
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• 2008

Infection of pathogenic microsporidia, Nosema bombycis and Nosema mylitta (Chakrabarti and Manna, 2006) decreased egg production, fecundity, hatching % and increased sterile eggs in heavily infected mulberry silkmoth, Bombyx mori L. On an average a disease free moth laid upto 442.67 eggs with high hatching % (99.53) and less sterile eggs ($0.47{\sim}2.00%$). While an infected moth laid less number of eggs ($7.00{\sim}412.00$) with low hatching % ($32.437{\sim}98.643$) and high sterile eggs ($2.143{\sim}129.571$). Fecundity of disease free laying was highest (468.714) during season-1 then gradually decreased during season- 2 (414.000) to season- 3 (404.285). But fecundity of an infected laying was highest during season-2 and hatched eggs were lowest during season-2. Higher inoculums concentration of N. mylitta infected to 5th stage larva of mulberry silkworm drastically decreased the fecundity in season - 3 and lower inoculums concentration of N. bombycis decreased the fecundity in season-1 and 3. Season-3 was most effective season to decrease the fecundity and increase sterile eggs when both temperature and humidity were fluctuated from the optimum level.

• International Journal of Industrial Entomology and Biomaterials
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• 제27권2호
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• pp.282-288
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• 2013

In nature, the population of Nosema bombycis (Microsporidia) causing pebrine disease is small and their development is extremely slow and only few ultimately producing spores. Pebrine infected silkworm, Bombyx mori larvae collected from sericulture field were alive till $3^{rd}$ generation though the concentration of N.bombycis spore was very high ($2.4-3.0{\times}10^8$ spores. $mL^{-1}$). All larvae were died during $4^{th}$ generation with extremely high concentration of pebrine spores ($3.0-4.0{\times}10^9$ spores. $mL^{-1}$) and mostly contain long polar tube (LT). Alternately, all larvae were died immediately (at $3^{rd}$ stage of $1^{st}$ generation) when it was artificially inoculated with same concentration of N.bombycis spores harvested from field ($2.4-3.0{\times}10^8$ spores. $mL^{-1}$) though concentration of spores harvest was very less ($3.0-4.0{\times}10^6$ spores. $mL^{-1}$) and mostly contain short polar tube (ST). Artificially pebrine infected male moth when mated with healthy female moth took six generations to develop pebrine disease and all larvae were died at the $2^{nd}$ stage with very less spore harvest ($3.0-10.0{\times}10^6$ spores. $mL^{-1}$). Survival percentage was increased in all generations (~92.0% at $4^{th}$ generation) when silkworm rearing was conducted under new integrated disease management system.

• 한국잠사곤충학회지
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• 제27권1호
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• pp.1-11
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• 1985

1979년 경북지방에서 발생한 병잠으로부터 분리된 새로운 미포자충 K79의 형태, 성장, 발육경과 및 분류학적 위치를 구명하기 위하여 포자의 병원성, 광학현미경에 의한 감염조직의 소견, 전자현미경적 소견을 조사한 결과는 다음과 같다. K79포자의 병원성은 N. bombycis 보다 약하였고 누에에 대한 K79의 감염부위는 중양피막세포, 혈구, 기관피막, 지방조직, 견사선이었다. K79의 발육과정은 sporoplasm, schizont, sporont, sporoblast, spore의 단계로서 N. bombycis와 유사하였으나 발육속도는 늦었다. 미포자충 포자의 전자현미경적인 미세구조는 포자외각의 돌출부와 돌출부사이가 44.28mm였다. 또한 anchoring disk는 우산형이었고 polaroplast, lamellae는 manubroid 상단부에 부착되어 있었다. 극사의 coil 전회수는 K79 16회이고 coil 각도는 75$^{\circ}$였고, 핵은 두 개의 연핵으로 되어 있어 분류학적으로 보면 Nosema 속에 속하는 신종의 미포자충이라고 사료되며 그 표기는 Nosema sp. K79로 기록함이 타당하다고 본다.

• International Journal of Industrial Entomology and Biomaterials
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• 제11권1호
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• pp.63-69
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• 2005

While observing silkworm larval samples received from field, microsporidian spores formed within the haemocytes of silkworm haemolymph were observed. The spores of microsporidian sp. were purified and characterized for morphological characters viz., size, shape as well as serological affinity with different Nosema spp. (M$_{11}$ and M$_{12}$). The infectivity of the isolated spores to silkworm was also studied. The microsporidian sp. was found to be highly pathogenic to silkworm, B. mori. The isolated microsporidian sp. was designated as NIK-5hm, which formed ovocylindrical spore in the haemocytes of silkworm and differed in spore size (length, 4.55 $\mu$m & width, 2.10 $\mu$m) and shape from Nosema bombycis (NIK-ls), NIK-2r (Nosema sp. Mysore [3.6 & 2.8 $\mu$m]), NIK-3h (Nosema sp. M$_{11}$ [3.8 & 1.8 $\mu$m]), NIK-4m (Nosema sp. M$_{12}$ [5.0 & 2.1 $\mu$m]) and Lb$_{ms}$ (Nosema sp. in Lamerine breed of silkworm [4.36 & 2.14]). In immonological test (Latex agglutination test), the isolated microsporidian spores did not react with antibody sensitized latex particles of N. bombycis, M$_{11}$, M$_{12}$ and Lb$_{ms}$ and thus are different type of microsporidian sp., parasitic to silkworm, Bombyx mori L.