No abstract

Newly evolved productive bivoltine hybrid CSR2 x CSRS rearing was conducted with differentie larval densities ranging from 50 larvae / sq.ft to 100 larvae / sq.ft in fifth instar. The cocoon character, a t cocoon yield and disease incidence was recorded with optimum rearing conditions as well as in the presence of 1 per cent infectious source (Flacherie and Grasserie). The results revealed that the cocoon characters were significantly improved and diseases incidence were reduced under low densityrearing (50 & 60 larvae/ sq.ft). However, there was no significant difference between 50 & 60 larvae/sq.ft. treatments with regard to spread of flacherie and grasserie

The immune system in insects involves in clearing the haemolymph of foreign pathogens by haemocytes and humoral factor. They can accomplish this in a couple of different ways. One is a cellular mediated response by physically clearing the haemolymph by phagocytosis, nodulation and encapsulation and the other is by humoral secretion of proteins. Pathogenic infection in silkworm, Bombyx mori L. is common and there is a possibility of differential response by haemocytes in different breeds to microbial infection. Hence, the differential response in the form of difference in Total haemocyte count (THC) and Differential haemocyte count (DHC) in susceptible and tolerant breeds were investigated under normal and Beauveria bassiana invasion conditions. Under normal condition, there was a gradual increase in THC as the age of the silkworm increases and high THC was recorded in Nistari, PM and NB4D2 (tolerant breeds) compared to susceptible breeds (NB7, NB18 and KA). There was a gradual increase in THC, gradual decrease in prohaemocyte and oenocyte counts and increase in plasmatocyte and granulocyte counts during the progressive infection by Beauveria bassiana.