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Chutia M.,Central Muga Eri Research and Training Institute | Ahmed G.U.,Gauhati University
BioTechnology: An Indian Journal

Extracellular pigment-producing ascomycetous filamentous fungi belonging to the genera Penicillium was obtained from soil and its optimal culture conditions investigated. The effect of nutrient culture media, pH and temperature on growth, sporulation and pigment production of three Penicillium species isolated from virgin forest floors of North east India was studied to optimize the mycelial growth and secondary metabolite production. Culture media significantly affected the growth, sporulation and conidial discharge of the species. The average colony growth of the three Penicillium species was higher in Malt Extract Agar (MEA) medium (4.1±0.59cm) whereas spore production was higher in Potato Dextrose Agar (PDA) medium (87.3±3.1). The optimal culture conditions for pigment production were as follows: inoculum's age, 7 days; temperature, 25 °C; pH, 6 and medium, PDA. Mycelial growth had also a significant correlation with the media pH and incubation temperature together with the pigment production. Under the optimal conditions obtained in the flask culture tested, the isolates secreted coloured pigments into the culture medium which was dependent on the pH of the solution. The high concentration of pigments produced by Penicillium species may be utilized for commercial production of pigments or the metabolites having industrial importance. © 2012 Trade Science Inc. - INDIA. Source

Sarkar B.N.,Central Muga Eri Research and Training Institute | Dutta K.,Gauhati University
Journal of Advanced Zoology

In the ecoraces of eri silkworm, Samia ricini (Donovan) critical difference among each rearing and grainage characters in different ecoraces were observed after analyzed of data of eight consecutive generations. Different grainage characters such as moth emergence (97-98%) higher coupling realization (37-38%), higher fecundity (345-440 nos.) and higher hatching (80-89%) was found significantly high in case of Diphu, Borduar and Barpeta ecoraces. Maximum hatching (89%) maximum larval weight (8.30-9.40 gm.) and more cocoon weight (3.00-4.74 gm.) found in case of Diphu, Borduar and Barpeta ecoraces. Pupal weight (2.68-4.18 gm.), shell weight ( 0.39-0.56 gm) and ERR (70-77%) was also found more in Diphu, Borduar, Barpeta and Kokrajhar ecoraces according to different season. Generally silkworm showed longer duration in larval life during the winter season than spring, summer and autumn season. Similarly, other characters viz. cocoon weight shell weight, cocoon yield were lower during the winter than the spring and autumn season. Moreover fecundity and hatching of eggs also showed lower in summer and winter season than autumn and spring season. During the summer season, the silkworm ecoraces showed low performance of economic traits than winter, spring and autumn seasons, probably for high temperature and high humidity. After the analysis of the growth and economic traits of different eri silkworm found that ecoraces viz. Diphu, Borduar and Barpeta are the most promising eri silkworm ecoraces for commercial exploitation. Finally these selected stocks are recommended for commercial rearing. Source

Kumar R.,Central Muga Eri Research and Training Institute | Mittal V.,Central Sericultural Research and Training Institute | Chutia P.,Central Muga Eri Research and Training Institute | Ramamurthy V.V.,Indian Agricultural Research Institute

The parasitic lepidopteran insect, Fulgoraecia melanoleuca (Fletcher) has been reported as an ectoparasitoid of Pyrilla perpusilla (Walker) from the Indian subcontinent. For the first time, the complete morphology, field biology, egg laying behavior, larval pupal, and adult morphology, including male and female gentialic features, are described and illustrated. Copyright © 2015 Magnolia Press. Source

Renthlei C.Z.,Central Muga Eri Research and Training Institute | Raghuvarman A.,North - Eastern Hill University | Kharbuli B.,Central Muga Eri Research and Training Institute | Dey S.,North - Eastern Hill University
Microscopy Research and Technique

The egg of Samia ricini (Donovan), is oval or laterally flattened ellipsoid, freshly laid eggs are candid white while the chorion is colorless and semi-transparent. The surface of the chorion is covered with network patterns of polygons and their shapes are common in the whole surface region. The boundaries between polygons made ridges had distinct acropyles at three-cell junctions. The numbers of aeropyles are variable according to their structures both in the lateral flat and marginal regions. During the course of egg development, no significant structural changes were observed in either the polygonal structures or the overall morphology of the egg. However,the size of the aeropyles kept on changing as the egg matures. The aeropyle increases initially upto day-9 of egg development and then decreases as it approach hatching. Lines of weaknesses were not observed at time of hatching or close to it. Hatching process of the newly emerge larvae are through gnawing. The larva eats their way out through the chorion membrane mostly from the anterior region. Egg buster or spine which aid in hatching are not present in the newly emerge larvae. ©2009 Wiley-Liss, Inc. Source

Das R.,Central Muga Eri Research and Training Institute | Das K.,Central Muga Eri Research and Training Institute
Indian Silk

The spread of muscardine disease in pre-seed muga silkworm crops and the steps taken to manage it are discussed. The disease is transmitted by a sexual structure of the fungus B. bassiana that forms spores on the outer body surface of the diseased muga silkworms after its death, contaminated with muga food plant leaves and rearing appliances. Selection of better quality seeds is one of the most significant steps that needs to be taken to manage the spread of the disease in such silkworm crops. Use of disease free seed is necessary for muga culture and the certified seed produced by different government agencies and NGOs prevents disease transmission. Deep ploughing of the rearing field before and after the rearing of muga silkworm is another steps that helps to eliminate inoculum of the pathogen from the soil. Source

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