• 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.

• International Journal of Industrial Entomology and Biomaterials
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• v.29 no.2
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• pp.169-178
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• 2014

In this study, we investigated genetic diversity of 22 microsporidian isolates infecting tropical tasar silkworm, Antheraea mylitta collected from various geographical forest locations in the state of Jharkhand, India, using polymerase chain reaction (PCR)-based marker assay: random amplified polymorphic DNA (RAPD). A type species, NIK-1s_mys was used as control for comparison. The shape of mature microsporidians was found to be oval to elongate, measuring 3.80 to $5.10{\mu}m$ in length and 2.56 to $3.30{\mu}m$ in width. Of the 20 RAPD primers screened, 16 primers generated reproducible profiles with 298 polymorphic fragments displaying high degree of polymorphism (97%). A total of 14 RAPD primers produced 45 unique putative genetic markers, which were used to differentiate the microsporidians. Calculation of genetic distance coefficients based on dice coefficient method and clustering with un-weighted pair group method using arithmetic average (UPGMA) analysis was conducted to unravel the genetic diversity of microsporidians infecting tasar silkworm. The similarity coefficients varied from 0.059 to 0.980. UPGMA analysis generated a dendrogram with four microsporidian groups, which appear to be different from each other as well as from NIK-1s_mys. Two-dimensional distribution based on Euclidean distance matrix also revealed considerable variability among different microsporidians identified from the tasar silkworms. Clustering of few microsporidian isolates was in accordance with the geographic origin. The results indicate that the RAPD profiles and specific/unique genetic markers can be used for differentiating as well as to identify different microsporidians with considerable accuracy.

• International Journal of Industrial Entomology and Biomaterials
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• v.6 no.1
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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.

• Journal of Sericultural and Entomological Science
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• v.33 no.1
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• pp.27-31
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• 1991

Microsporidian spores were isolated from yellow-hind winged arctiid, Eilema griseola (Hubner), and cutworm, Agrotis tokionis Butler, and their morphological characteristics and their indectivity to silkworms were investigated. The shape of the microsporidian isolates was oval and the sige of the spore isolated from yellow-hind winged was measured in 2.6$\times$1, 5$\mu$ and that of the isolated from cutworm was measured in 3.7$\times$20.$\mu$. Both the isolated microsporidians showed the infectivity to silkworms, but the isolates did transovarian transmission in silkworms and the silkworm moth infected with the isolate from yellow-hind winged laid eggs irregularly.

• 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.