• 제목/요약/키워드: nosema bombycis

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Light and Electron Microscopic Study on the Development of Nosema Bombyics Naegeli in the Midgut of Silkworm Bombyx Mori L.

  • Jyothi, N.B.;Patil, C.S.
    • International Journal of Industrial Entomology and Biomaterials
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    • 제23권1호
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    • pp.107-113
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    • 2011
  • Infection effect of $Nosema$ $bombyics$ on the midgut of silkworm $Bombyx$ $mori$ and subsequent appearance of spores and the performance of larvae was studied. Autopsy of larvae showed white pustules on the surface of midgut at 5 days of post infection (pi). At later stage, important organs like midgut, silk gland and gonads reduced in size and all these organs showed white pustules. Light microscope observation of pustules revealed enormous spores. Spore multiplication was at a faster rate in young larvae. Infection of the adult larvae resulted in pebrinized pupa and moths. Larval weight, cocoon weight and cocoon shell ratio reduced as the post infection period increased. Transverse sections of midgut showed $N.$ $bombycis$ infection limited to a few columnar cells at 3-5 days of pi. At 7 days pi, cell volume increased, cells were swollen and elongated. Heavily infected cells looked like sacks filled with parasite and the apical region of certain cells were bulging into the gut lumen. Later at 8-9 days of pi, spores or its developing stages leaked into the lumen either freely or enclosed within the globules of host cytoplasm. Besides columnar cells, development of $N.$ $bombycis$ was observed in the regenerative cells and rarely in goblet cells. Development of $N.$ $bombycis$ was also observed in both longitudinal and circular muscles at the late pi period. The histopathological changes, deformities and spore production time in the host were all influenced by the spore dosage and age of the host.

Mode of Transmission of a Newly Discovered Microsporidian and Its Effect on Fecundity and Hatching in Silkworm, Bombyx mori L.

  • Bhat Shabir Ahmad;Nataraju B.
    • International Journal of Industrial Entomology and Biomaterials
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    • 제11권2호
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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.

Influence of Temperature and Relative Humidity in Infection of Nosema bombycis (Microsporidia: Nosematidae) and Cross-infection of N. mylitta on Growth and Development of Mulberry Silkworm, Bombyx mori

  • Chakrabarti, Satadal;Manna, Buddhadeb
    • International Journal of Industrial Entomology and Biomaterials
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    • 제17권2호
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    • pp.173-180
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    • 2008
  • The influence of temperature and relative humidity in infection and cross-infection of Nosema bombycis and N. mylitta respectively in mulberry silkworm, Bombyx mori L. on larval mortality, multiplication of pathogens, larval weight and growth rate in three different seasons were studied. Seasons were selected in such condition, when very less fluctuations between minimum and maximum temperature and minimum and maximum relative humidity ($25{\sim}28^{\circ}C$ and $65{\sim}72%$ R.H) was observed i.e., season-1. Fluctuations between minimum and maximum temperature were less ($28.05{\sim}34.50^{\circ}C$) but R.H % was more ($55{\sim}81%$) in season-2. Fluctuations between minimum and maximum temperature and R.H % were more ($20.00{\sim}40.5^{\circ}C$ and $64.00{\sim}90.00%$) in season-3. Growth rate of microsporidian-infected silkworm is directly related to the prevailing temperature and relative humidity in silkworm. Silkworm can tolerate slight variation of temperature but slight variation of relative humidity disfavours the development of silkworm and favours the multiplication of pathogens.

Influence of Temperature on Microsporidian Multiplication and Spore Production in Various Tissues of Silkworm (Bombyx mori L.) During Larval Development

  • Mohanan N. Madana;Krishnan N.;Mitra P.;Das K.K.;Saratchandra B.;Haldar D.P.
    • International Journal of Industrial Entomology and Biomaterials
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    • 제12권2호
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    • pp.87-93
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    • 2006
  • Multiplication and spore production of three microsporidia viz., Nosema bombycis, Nosema sp. 1 and Nosema sp. 2 in fifth instar larval tissues of silkworm, Bombyx mori L. in two seasons with distinct temperature regimes were studied. Nosema sp. 2 produced significantly (P < 0.01) higher number of spores in various tissues. Among the tissues, spore production was highest in silk gland, followed by fat body and gut. Spore production was significantly (P < 0.01) higher in season-II (Average temperature $29.4{\pm}1.1^{\circ}C$). Maximum spore production was observed 25 days post inoculation (p. i.) in season-I (Average temperature $18.9{\pm}1.1^{\circ}C$), whereas in season-II, it was 14 days p. i. In season-I, spore production was low up to 21 days p. i., then increased sharply. In season-II, there was a steady increase in spore production. The results indicate that the microsporidian multiplication is tissue specific and extremely sensitive to temperature at which the host is reared. It also reveals that, silk gland, fat body and gut are the most appropriate tissues for microscopic identification of microsporidia in the larval stage.

Preliminary Study on a Microsporidian Isolate Occurring in the Lamerin Breed of the Silkworm Bombyx mori L. in India

  • Bhat, Shabir Ahmad;Nataraju, B.
    • International Journal of Industrial Entomology and Biomaterials
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    • 제9권2호
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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.

Microsporidian Disease of the Silkworm, Bombyx mori L. (Lepidoptera: Bombycidae)

  • Singh, Tribhuwan;Saratchandr, Beera
    • International Journal of Industrial Entomology and Biomaterials
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    • 제6권1호
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    • pp.1-9
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    • 2003
  • The silkworm, Bombyx mori, 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 loss to the sericulture industry. Several strains and species of microsporidians have since been isolated from the infected silkworms; the disease is becoming increasingly more and more complex. Epizootiology, development of immunodiagnostic kit, use of chemotherapy and thermotherapy techniques has been addressed for identification and control of the disease. A technique of delayed mother moth examination, which plays a decisive role in the detection of the disease and harvestation of stable cocoon crop, has been described. An attempt has been made to review briefly the literature available on various aspects of the pebrine disease in order to develop efficient model(s) for the prevention and control of the disease and to suggest future avenues of investigation in the field of pebrine disease management.

원종 및 교잡종에 대한 미립자의 병원성에 관한 연구 (Studies on Pathogenicity of Nosema bombycis Naegeli to Parents and Hybrid in the Silkworm (Bombyx mori L.))

  • 김종수;김문협;채수군;임종성
    • 한국잠사곤충학회지
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    • 제14권2호
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    • pp.81-92
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    • 1972
  • 미립자 병원체의 병원성에 대한 연구로서 그 결과를 요약하면 다음과 같다. 1. 품종별 감잠비율에 있어서 원종은 교잡종보다 훨씬 높았으나 원종간에는 차이가 없었다. 2. 첨식농도별, $10^{5}$ /ml<$10^{6}$/ml<$10^{7}$ /ml<$10^{8}$ /ml순으로 감잠비율이 높았다. 3. 영별로는 5령<4령<3령<2령 순으로 감잠비율이 높았다. 4. 품종과 농도 사이의 감잠비율에 대한 교호작용에 있어서 1) 고농도($10^{8}$ /ml)에서는 원종과 교잡종간에는 차이가 없었으며 2) 저농도($10^{5}$ /ml)에서는 교잡종은 원종보다 낮았으나 원종간에는 차이가 없었다. 3) 중간농도($10^{7}$ /ml, $10^{6}$/ml)에서는 교호작용이 엇갈려 원종의 $10^{6}$/ml과 교잡종의 $10^{7}$ /ml에서 교호작용이 같았다. 5. 면역에 있어서 N. bombycis포자의 면역방법은 항원 주사량, 면역기간 및 주사간격이 중요하며 특히 항원 주사량은 20ml($10^{8}$ spores/ml)이상이 필요한 것으로 생각되며 4처리구(A.B.C.D)중에서 D구가 제일좋았다. 6. N. bombycis의 생존포자를 면역원으로 해서 토끼에 면역시키면 간접법 염색에 의한 항체가에서 1 : 12, 800의 항체가 N. bombycis 면역혈청을 얻었으며, 잠체조직 및 N. bombycis의 포자는 자기 형광을 볼 수 있었으나 U.V. filter로 관찰하게 되면 FITC의 형광색을 명확히 식별할 수 있었다. 7. 미립자 병잠의 소직학적 관찰에서 미립자 포자는 누에 조직 중에서도 제일 먼지 중위피막조직에 기생하는 것을 알 수 있었다.

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Serichlor, A New Disinfectant in Indian Sericulture

  • Balavenkatasubbaiah M.;Nataraju B.;Sharma S.D.;Selvakumar T.;Chandrasekharan K.;Rao P. Sudhakara
    • International Journal of Industrial Entomology and Biomaterials
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    • 제12권1호
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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.

가잠(家蠶)으로부터 분리(分離)된 새로운 Microsporidia S80의 특성(特性) (Characteristics of New Microsporidia S80 Isolated from Silkworm, Bombyx mori L. in Korea)

  • 임종성;조세연
    • Current Research on Agriculture and Life Sciences
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    • 제1권
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    • pp.67-83
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    • 1983
  • 1980년(年) 한국(韓國)에서 발견(發見)된 Microsporidia S 80은 포자(胞子)의 길이가 $2.9{\pm}0.28{\mu}$ 폭(幅)이 $1.7{\pm}0.29{\mu}$으로 난원형(卵圓形)인데 그 크기가 형태(形態)로 보아 누에에 기생(寄生)하는 Microsporidia로서 지금까지 한국(韓國)이나 일본(日本)에서 알려진 것 들과는 다른 것이다. 과산화수소(過酸化水素) 원액(原液)으로 처리(處理)하였을때에 추출(抽出)된 극사(極絲)의 길이는 평균(平均) $26{\mu}$이었고 극사(極絲)의 선단(先端)에서 둥근 모양의 sporoplasm이 돌출(突出)되어 있는 것이 관찰(觀察)되었다. 한편 포자(胞子)는 Giemsa, Safranin-O, Gram 등(等)의 염색(染色)에서 부분적(部分的)으로 염색(染色)되는 특징(特徵)이 나타났으며, 전자현미경(電子顯微鏡)으로 관찰(觀察)한 포자(胞子)의 미세구조(微細構造)는 제일 바깥 부분(部分)이 전자밀도(電子密度)가 높고 요철(凹凸)이 있는 얇은 exospore로 둘러싸여 있고 그 안쪽에는 투명(透明)하고 두꺼운 endospore가 있는데 endospor는 포자(胞子)의 정단부(頂端部)가 다른 부위(部位)보다 상당히 얇은데 이곳으로 극사(極絲)가 추출(抽出)되는 것으로 생각된다. endospore와 cytoplasm과의 경계부(境界部)에는 세포질(細胞質)을 싸고 있는 한층(層)의 한계막(限界膜)인 inner limitting layer가 있다. 세포질(細胞質)의 전단부(前端部)에는 polar cap이 있고 그 밑에는 lamellar 구조(構造)의 발달(發達)된 polaroplast가 있으며 polaroplast의 후부(後部)는 vesiculate part로 되어 있는 것으로 보인다. polar filament는 anchoring disc인 polar cap에서 곧게 뻗어 나아가다가 포자(胞子)의 내벽(內壁)을 따라 돌면서 용수철 처럼 말려 있는데 polar filament의 coiled part 중앙(中央)에 2중막(重膜)에 싸여진 전자밀도(電子密度)가 높은 후형질(厚形質)로된 2핵(核)이 인접(隣接)하여 있으며 포자(胞子)의 부단부(部端部)에는 posterior vacuole이 있을 것이다. 이러한 포자(胞子)의 크기와 형태(形態) 및 미세구조(微細構造)로 보아 Microsporidia인 것을 확인(確認)할 수 있으며 분류학(分類學) 상(上)의 위치(位置)는 Microsporea 강(綱), Microsporidia 일(日)에 소속(所屬)시킬 수 있고 아목(亞目) 및 속(屬)을 규명(糾明)하기 위(爲)해서는 그 생활사(生活史)가 밝혀져야 한다. Mcrosporidia S80을 2령(齡) 기잠(起蠶)에 경구접종(經口接種)한 경우(境遇)의 LD50은 $7.1{\times}10^7/ml$로서 $1.2{\times}10^7/ml$인 Nosema bombycis와 비교(比較)할때 병원성(病原性)이 낮은 것으로 나타났으나 그 발생지역(發生地域)이 경기도(京畿道)를 중심(中心)으로 인접지역(隣接地域)인 강원(江原), 충북(忠北) 충남(忠南) 및 전남(全南)에서도 발생(發生)되고 있는 점(點)과 4령기(齡期) 접종시(接種時) 전견중(全繭重)과 견층중(繭層重)에 나쁜 영향(影響)을 미칠뿐 아니라 화아비율(化蛾比率)이 낮고, 감염(感染)된 모아(母蛾)는 물론 감염(感染)된 웅아(雄蛾)와 교미(交尾)한 모아(母蛾)에서도 산란불능아(産卵不能蛾)가 발생(發生)하거나 산란수(産卵數)가 건전구(健全區)에 비(比)하여 떨어지는 동시(同時)에 부수정란(不受精卵) 비율(比率)도 높은 것으로 볼 때 사견양잠(絲繭養蠶)은 물론 종견양잠(種繭養蠶)에 있어서도 피해(被害)를 입고 있을 것으로 본다. 감염모아(感染母蛾) 21마리에서 얻은 차대잠(次代蠶)의 검사결과(檢査結果) 경란전달(徑卵傳達)은 되지 않는 것으로 나타났으나 혹시 경란전달(徑卵傳達)이 된다고 해도 그 빈도(頻度)는 매우 낮을 것이며 1/21 미만(未滿)일 것으로 생각된다.

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