• International Journal of Industrial Entomology and Biomaterials
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• v.17 no.1
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• pp.153-155
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• 2008

Pathogenic infection in tasar silkworm, Antheraea mylitta Drury is common and there is a breed specific response regarding tolerance. Hence, the tolerance level of three eco-races of tasar silkworm viz. Daba, Sarihan and Raily to Antheraea mylitta cytoplasmic polyhedrosis virus (AmCPV) infection was tested. The survival of Daba, Sarihan and Raily eco-races was significantly different (p<0.05) when challenged with the same concentration ($1{\times}10^5$ polyhedra/ml) of AmCPV. Daba eco-race was more tolerant to the AmCPV infection having higher survival (65.7%) and $LC_{50}$ values (1000893.17 polyhedra/ml) of AmCPV followed by Sarihan eco-race (50.7% survival and $LC_{50}$ value of AmCPV 187203.6168 polyhedra/ml) and Raily eco-race (24.3% survival and $LC_{50}$ value of AmCPV 5176.37 polyhedra/ml). The tolerance level of Daba and Sarihan eco-races against AmCPV was more than two times than Raily eco-race.

• International Journal of Industrial Entomology and Biomaterials
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• v.19 no.2
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• pp.249-253
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• 2009

Raily ecorace of Indian tasar silkworm is wild in nature and distributed abundantly in dense deciduous forest on Shorea robusta (Sal) in Bastar ($17^{\circ}4'$ and $20^{\circ}34'$ N, $80^{\circ}15'$ and $82^{\circ}15'$ E and altitude ranging from 150 to 1200 mMSL) forest ranges of Chhattisgarh, India. It is represented by about 20 populations. Out of those, eleven populations showed intra- as well as inter- population variability based on phenotypic expression and also in major economic traits viz. cocoon weight, shell weight, filament length and denier. Genetic diversity in these eleven populations was studied using Inter-Simple Sequence Repeat (ISSR) markers. The band profiles generated with eight ISSR primers have depicted variation in band size. All the primers exhibited polymorphism which is an indicative of the genetic variation in individual Raily silkworm. Among the populations, total polymorphism recorded was 76%. The population genetic aspects assessed through POPGENE software package are discussed in the paper. Nei's gene diversity (h) ranged from 0.194 to 0.337 exhibiting high heterozygosity. Relevance of the present study is of high significance in formulating conservation strategies and sustainable utilization of the economically important Raily ecorace of Antheraea mylitta.

• International Journal of Industrial Entomology and Biomaterials
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• v.20 no.2
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• pp.61-67
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• 2010

The bivoltine tropical tasar ecoraces of Antheraea mylitta Drury produces cocoons for seed production under seed crop rearing (July-August with $22{\sim}30^{\circ}C$ temperature and 50~70% relative humidity) and for silk production under commercial crop rearing (September-December with $17{\sim}27^{\circ}C$ temperature and 60~80% relative humidity). To consider the impact of hybrid vigour on egg, larva, cocoon and silk related commercial traits, the $F_1$ hybrids made among Daba, Jata and Raily ecoraces were assessed successively for three years. The hybrid vigour in the $F_1$ hybrid of Daba$\times$Jata ($T_7$) was positive for egg fertility (+23.1%), shell weight (+25.6%), silk yield (+79.0%) and filament length (+68.1%), with filament of high denier (11.98d) and reduced larval span (-7.1%). The Jata$\times$Daba ($T_8$) hybrid has shown negative heterosis in egg fertility (-8.0%) compared to the other F1 hybrids, Daba$\times$Raily ($T_9$) and Raily$\times$Daba ($T_{10}$), when they rise simultaneously during the commercial crop season. The better performance of parental ecoraces ($T_4$ to $T_6$) in their commercial traits during commercial crop over parents of seed crop ($T_1$ to $T_3$) and the superior performance of $F_1$ hybrids ($T_7$ to $T_{10}$) over parents of commercial crop ($T_4$ to $T_6$) during commercial crop season indicates the apparent hybrid vigour in tasar $F_1$ hybrids. As the Daba$\times$Jata ($T_7$) and Jata$\times$Daba ($T_8$) $F_1$ hybrids have shown highest hybrid vigour, their rearing during commercial crop can optimize the silk productivity and commercial sustenance of the tasar silk industry.

• International Journal of Industrial Entomology and Biomaterials
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• v.10 no.1
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• pp.51-59
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• 2005

Genetic diversity within and between populations of Antheraea mylitta Drury was studied using thirty individuals from three ecoraces using 12 ISSR and 10 RAPD primers. Rally, Daba and Modal ecoraces were collected from Chattisgarh, Jharkhand and Orissa states of India respectively. The ISSR and RAPD primers generated $94.7\%$ and $95.6\%$ polymorphism among the 30 individuals. The cluster analysis grouped these individuals according to their ecorace. The intra-ecoracial heterozygosity estimated with ISSR markers were $0.123{\pm}0.18,\;0.169{\pm}0.17\;and\;0.214{\pm}0.17$ respectively for Modal, Raily and Daba ecoraces. Like wise, with RAPD markers the intraecoracial heterozygosity was $0.17{\pm}0.22$ in Modal, $0.229{\pm}0.17$ in Raily and $0.23{\pm}0.19$ in Daba ecoraces. However, the significantly low genetic differentiation (GST) (0.182 for ISSR and 0.161 for RAPD) and the high gene flow (Nm) (2.249 for ISSR and 2.60 for RAPD markers) among the ecoraces revealed that the amount of genetic diversity present among the ecoraces is not significant enough to make drastic genetic drifts among these ecoraces in the near future.