Haemolymph Assay and Morphological Changes of Silkworm, Bombyx mori L. (Bombycidae: Lepidoptera) Infected with Bacillus thuringiensis var. sotto

Abstract

Sericulture is a distinctive field of agriculture in which silkworms, Bombyx mori (Bombycidae: Lepidoptera), are reared on wide range for commercial purpose. Silkworm is susceptible to various pathogenic diseases. Among the all bacterial diseases of B. mori, flacherie is injurious disease that is initiated by entomopathogenic bacteria, Bacillus thuringiensis var. sotto (Bts). The impact of this infectious disease is weight loss, reduction in cocoon quality as well as quantity and source of infestation for healthy larva. In current study, the 3 rd instar larva of B. mori were fed on the leaves of Morus alba treated with B. thuringiensis until the start of 5 th instar and the Total Haemocyte Count (THC) of the Bts infected silkworm's haemolymph were counted. The findings of current research showed that THC was significantly increased at 1 st and 2 nd day i.e., 5128/ml and 5704/ml as compared to control 3047/ml, respectively. Afterwards, THC were rapidly decreased and THC were recorded 1928/ml (3 rd day) and 344/ml (4 th day). The results also exhibited the morphological changes of silkworm i.e., infected larva fully filled with B. thuringiensis spores with flaccid body and haemolymph liquid impelled leading to mortality. Provide the required temperature and humidity with appropriate hygienic condition to B. mori are advised to produce healthy silk.