author(s)
A.R. Narasimha Nayaka, S.D. Sharma

abstract
The microsporidian infection has become increasingly complex today due to different species of microsporidians are being isolated from silkworm and other mulberry insect pests. In India, different microsporidian species viz., NIK-1s, IK-2r, NIK-4M, NIK-3h and NIK-4hm have been isolated from silkworm. Different microsporidian species differ in their site of infection, rate of multiplication and mode of transmission. Recently a new microspridian strain NIK-5hm was solated fromsilkworm which is different from other microsporidian species by havingspore formation inside the haemocytes and their mode of transmission. In the present study, the paradigm of vertical transmission of NIK-5hm is tudied in popular multivoltine and bivoltine breeds and it is observed that the new microsporidian strain NIK-5hm exhibit transovarial transmission both in multivoltine and bivoltine breeds to their progeny, but the rate of transmission ignificantly varies from standard strain, Nosema bombycisin both the breeds. The rate of transmission of NIK-5hm microsporidian to the F1 progeny in Pure Mysore (PM) and CSR2 ranges from 79.33-81.33% and 84.00- 6.33%respectively. Where as in case of Nosema bombycis the rate of transmission is 100% in both PM and CSR2breeds.