The effect of different stress factors on the spread of virosis and pebrine diseases in tasar silkworm rearing

Presence of the pathogens induces diseases in tasar silkworm rearing there after several ecological and nutritional factors influence diseases spread in general. There is no specific study on the spread of the diseases of tasar silkworm in different stresses. In the present study, Daba B.V was reared under different stress conditions involving temperature and humidity, larval density and leaf maturity in presence of infectious source of Virosis disease caused by Antheraea mylitta cytoplasmic polyhedrsis virus (AmCPV) and Pebrine disease caused by Nosema mylittansis in tasar silkworm rearing. These factors significantly influenced the spread of Virosis and Pebrine. The effect of environmental factors (temperature and humidity) as stress factor, the incidence of Virosis and Pebrine were low in control batches where as high in 1% source of diseases. The spread of Virosis was to the extent from 41.33% (T1) - 84.83% (T4) and Pebrine ranged from 36.00% (T1) – 79.83% (T4). Larval density as stress factor, as the number of larvae/sq. ft increased the incidence of Virosis and Pebrine was also significantly increased from 56.3% to 90.5% and 47.0% to 87.7%, respectively. Leaf maturity as a stress factor, in the treated lots as the maturity of the leaf increased from 90 days to 150 days, there was significant increase of mortality in comparison with control. Mortality due to Virosis and Pebrine ranged from 48.3% (T2) to 65.5 % (T4) and 40.3 % (T2) to 62.2 % (T4) respectively.