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Effect of Nuclear Polyhedrosis Virus on the Growth and Development of Silkworm Hybrids, Bombyx Mori L. (lepidoptera: Bombycidae)

B N Saha
Department of Zoology, University of Rajshahi, Rajshahi 6205, Bangladesh

A R Khan
Department of Zoology, University of Rajshahi, Rajshahi 6205, Bangladesh

Abstract/ Executive Summary:

Objective of this study was to determine the effects of Bm NPV- treated leaves on the growth and development of various hybrids of B. mori. Effect of nuclear polyhedrosis virus (NPV) on the growth and development of the silkworm hybrids, Bombyx mori L. has been reported. The pathogen produced detrimental effects on the growth of larvae, pupae and adults (P<0.001). The developmental periods of the treated silkworms were also significantly lengthened (P<0.001). Both the silkworm genotypes and NPV significantly affected the growth and development of B. mori.

Keywords: Growth, Development, Silkworm, Hybrids, Nuclear polyhedrosis virus

Location: Silkworm Research Laboratory, Department of Zoology, University of Rajshahi

Start Date: 01-01-1994

End Date: 30-06-1995

Program Area: Pest Management

Commodity: Virus

Objectives:

To determine the effects of Bm NPV- treated leaves on the growth and development of various hybrids of B. mori.

Methodology:

The local multivoltine race, Nistari and five exotic bivoltine races, namely BV (P), Dong 34 (M), RB (P), RB 001 and Zianghsu 12 (P) were used in this experiment. The indigenous and homogeneous race, Nistari has the capacity to resist high temperature and humidity but it is poor in silk - yield. All the are relatively susceptible to high temperature and humidity but are popular in respect of high silk - yield. In breeding, both multivoltine and bivoltine races were used for possible combinations including reciprocals and ten hybrids were prepared. The rearing was conducted in a randomized block design following the new technology of silkworm rearing. The parental line was first reared. The F₁ generation and normal parental lines were reared separately. Eleven genotypes of newly - hatched silkworm larvae were reared up to their second moult on fresh, tender mulberry leaves. Leaves were chopped and supplied to the worms four times a day. Before feeding, the polyhedra were extracted from the heavily NPV - infected silkworm larvae by clipping off caudal horns and prolegs and then purified by repeated centrifugation (at 1800 - 2000 rmp for 20 minutes) in 25 and 50% sucrose solutions. Finally, the sediments were resuspended in sterilized distilled water. The polyhedral suspension bearing a fixed load of 120 - 150 polyhedra per microscopic field at 600 x was smeared on the mulberry leaves. For each feed freshly prepared suspensions were used. The concentrations of the suspension @ 400, 800, 1600, 3200 and 6400 polyhedra/ litre were prepared by mixing required quantities of polyhedra in distilled water. A control batch was also raised on leaves treated with distilled water only. There were three replications per treatment of concentration, each with 150 larvae, in all the genotypes. The leaves were treated with various concentrations of the polyhedra by dipping mulberry leaves in polyhedra solution and left for complete absorption/ evaporation under room temperature. After the second moult larvae were reared on treated mulberry leaves up to spinning. Observations on the weight (mg) and developmental periods (day) of B. mari larvae were recorded and statistically analyzed. All the experiments were conducted at 20 ± 1°C and 79 ± 4% relative humidity. The investigation was undertaken at the Silkworm Research Laboratory, Department of Zoology, University of Rajshahi,

Source of Information: JOURNAL OF BIO-SCIENCE, THE INSTITUTE OF BIOLOGICAL SCIENCES RAJSHAHI UNIVERSITY, Vol. 13, 2005, pp. 15-22, ISSN 1023–8654.

Article Link (Online Journal):

Funding Source:

Total Budget (Tk.) :

Achievement/Findings:

From this study it was found that the pathogen produced detrimental effects on the growth of larvae, pupae and adults (P<0.001).

Knowledge Management: Journal