Impact of Feeding Selected Mulberry Germplasm Varieties on Silkworm Bombyx Mori L.through Bioassay Techniques for Commercial Exploitation

A critical evaluation study comprising five mulberry varieties viz., S1708, MS5, C10, C6 and M5 was conducted for their leaf quality through silkworm moulting and rearing using crossbreed (PMxNB4D2) silkworms. Results revealed that, in moulting tests, silkworm larvae reared on S1708 mulberry leaves recorded highest larval weight (25.03mg) and moulting ratio (84.96%) and lowest larval weight (17.04mg) and moulting ratio (71.06%) recorded in silkworms reared on C6 leaves during II moult. Silkworms reared on S1708 leaves recorded highest larval weight (39.08mg), cocoon weight (1.90g), shell weight (0.41g), shell percentage (21.66%), filament length (957.57mts), reelability (86.88%), renditta (6.06), denier (2.08) and E.R.R (88.31%), whereas lower larval weight (26.20g), cocoon weight (1.30g), shell weight (0.19g), shell percentage (16.18%), filament length (722.60mts), reelability (56.12%), renditta (8.30), denier (2.62) and E.R.R (78.86%) were observed in C6 mulberry leaves. It is clear from the results that, mulberry variety S1708 turns out to be superior in bioassay tests compared to other varieties studied

Induction of Useful Mutation in Mulberry (Morus) Variety S54 by Gamma Irradiation in M1 Generation

Aims: Plentiful mulberry varieties available in nature, they lack one or the other important economic trait required for silkworm Bombyx mori L. as food. Efforts have been made to induce phytomorphological variability in mulberry variety S54 using gamma rays. Experimental Design: RBD Method with three replications/treatment was followed. Place and Duration of Study: Mulberry garden, Department of Sericulture, Jnana Bharathi, Bangalore University and Mist chamber, Indian Institute of Horticultural Research (IIHR), Bangalore, Karnataka, India between 2006-2011. Methodology: Gamma ray (1kR-10Kr) was used to induce variability in juvenile twigs of mulberry for various agro-botanical characters viz., sprouting, rooting, internodal distance, leaf area, plant height etc. and leaves were subjected to biochemical analysis. Results: Mulberry variety S54 showed linear decrease in growth parameters with the increased gamma ray dosage and plants exhibited variability with increased rooting (81.33%), plant height (147.86cm) and leaf area (146.22cm2) when compared to control in M1 generation at 7kR. Mutants showing favourable characters were grown for M2 generation which exhibited marked improvement in growth and yield parameters. Biochemical constituents in S54 mutant leaves recorded at 7kR showed increased proteins, carbohydrate, chlorophyll a and b. Conclusion: Mulberry cuttings irradiated with gamma ray (7kR) exhibited favourable traits in rooting, plant height and leaf area over the control in M1 generation and mutants were grown for M2 generation and marked improvement in growth, yield and bio-chemical parameters were observe

Efficacy of fungicide ‘Kavach’ against Beauveria bassiana L. in silkworm Bombyx mori L.

Silkworm Bombyx mori L. is prone to be attacked by pathogen and more notably Beauveria bassiana L. Bed disinfectant Kavach was inoculated in different dosages (0.2%-1.6%) to IV and V instar silkworms of both bivoltine and cross breeds. Potency of disinfectant was assessed for the parameters such as survivability, larval duration, physiological, chemo and bio-assay tests. It was revealed that, bivoltine (NB4D2) silkworms were highly susceptible to diseases compared to cross breeds (PMxNB4D2). In bivoltine silkworms, survivability was found to be 61.15% at 1.6% of Kavach, when dusted twice during IV and V instar and crossbreed silkworms exhibited better resistance of 63.10% with the same treatments. Kavach treated silkworms showed decreased larval duration compared to control worms. Crossbreed silkworms were capable of maintaining high level of soluble proteins in spite of infection on 3rd day (17.40%), 4th day (20.50%) and 5th day (21.55%) whereas in bivoltine silkworms soluble protein level was brought down on 3rd day (19.30%), 4th day (22.40%) and 5th day (23.40%). Total soluble sugarsvaried from third day till fifth day in both the races. Kavach dusted twice at 1% proved to be very useful in the improvement of various commercial cocoons characters

Changes in the activity of digestive enzymes in response to chemical Mutagen Diethyl Sulfate in the silkworm Bombyx mori L. (Lepidoptera: Bombycidae)

The silkworm Bombyx mori L. is a economic sericigenous insect show a high degree of sensitivity towards chemical mutagens and have drastic physiological and biochemical effects during its larval stages. In the present study a bivoltine race of silkworm NB 4D 2 was treated with chemical Mutagen Diethyl Sulfate (DES). The larvae were used for the treatment with different concentrations of DES orally as well as injected through body wall. In F 1 generation, the larvae of 4th and 5th instar were used to study the activity of prominent digestive enzymes amylase and protease for evaluation of the mutagenic response in haemolymph and midgut tissues. The enzyme activity was found to be higher in treated sets, particularly in 8 mM injection sets. Further, maximum enzyme activity was noticed during middle part of both the instars with a few variations among the treated sets. The data were statistically analysed using One-way ANOVA and discussed. © 2012 Knowledgia Review, Malaysia