A STUDY ON THE PREVALENCE OF WHITE SPOT SYNDROME VIRUS (WSSV) IN WILD SHRIMP Penaeus monodon (FABRICIUS, 1798) AND EXPERIMENTAL EVALUATION OF ITS INFECTIVITY ON MUD CRAB Scylla olivacea (HERBST, 1796) AN ASYMPTOMATIC CARRIER OF WSSV

Shrimp farming has changed from traditional small scale to ultra intensive farming system in South-East Asia. Due to intensification, which ultimately leads to number virulent disease outbreaks in grow out, nursery and also in the wild. Among the diseases, the White spot syndrome virus (WSSV) outbreak is a notorious pathogen belongs to the Genus whispovirus, family Nimaviridae and it was first identified in the early 1990's. The serious outbreak of WSSV in shrimp grow-out farms and also the prevalence white spot syndrome virus (WSSV) infection in the wild population including the wild brooders affected the Penaeus monodon culture worldwide and also India. In the present study, an attempt was made for the investigation of the prevalence of WSSV in the wild Penaeus monodon population i-e Vellar Estuary. Further, PCR confirmed WSSV positive wild shrimps were fed (oral ingestion) to Penaeus monodon and mud crab (Scylla olivacea) for the infectivity study.  The shrimp infectivity study showed 100% mortality was reached on 5^th day of post infection and in the case of mud crab the chronic mortality started only on 35^th day abd extended beyond 45 days. Hence it is concluded that the mud crabs not only an asymptomatic carrier but also host for the WSSV.