EFFECT OF HERBAL EXTRACTS ON THE MICROBIAL PATHOGENS CAUSING FLACHERIE AND MUSCARDINE DISEASES IN THE MULBERRY SILKWORM, BOMBYX MORI L.

Abstract

ABSTRACT A preliminary survey on the incidence of silkworm diseases in ten selected sericulture farms near Srivilliputhur, a hub of sericulture activity in the Virudhunagar district of Tamilnadu, India showed that the incidence of the bacterial diseases, flacherie is quiet common in this region followed by the fungal diseases, muscardine and the viral diseases, Grassarie. Biochemical characterization of the microbes in the haemolymph of diseased silkworm collected during the survey indicated the presence of Bacillus sp., Streptococcus sp., Staphylococcus sp. and Pseudomonas sp. in the culture. The nature of fungal species however, could not be ascertained due to several handicaps including the difficulties encountered during their culture. Studies were carried out in vitro to assess the efficacy of some herbal extracts for the containment of these microbes through turbidimetry analysis and zone of inhibition test. The observations made during this study revealed that the aqueous and alcoholic crude extracts of three herbs such as, Acalypha indica, Ocimum sanctum and Tridax procumbens are effective against these microbes causing flacherie and muscardine diseases in silkworm. The comparison of their effects indicated that alcoholic extracts were generally more effective than aqueous extracts and that the extracts of Tridax procumbens are very effective against these microbial pathogens followed by the extracts from Ocimum sanctum and Acalypha indica. Extensive studies using these extracts on the growth and cocoon production of the mulberry silkworm, Bombyx mori L. are likely to throw much light on the possibility of using such extracts as a prophylactic measure during silkworm rearing to improve silk production.