The Sensitivity various stages of mud crab (Scylla paramamosain Estampador) to white spot syndrome virus

Abstract

Mud crab is the most commercial crabs which are highly sold because of their delicious taste and high protein content. In nature, the capture intensity of this crab is very high so the population would decrease rapidly. For this reason people start to breed it. At the moment breeding of mud crab still have a lot of problems. One of those is the lower survival rate of larva stage due to the diseases. The objective of this research was to observe the sensitivity of mud crab from various stages to White Spot Syndrome Virus (WSSV). The research was conducted in Pathology laboratory, Balai Besar Riset Perikanan Budidaya Laut Gondol, Bali, January to April 2004. This experiment was run using three stages they were zoea-1, zoea-3 and crablet stage. The treatment of this research were: for zoea-1 and zoea-3 stage, i.e. treatment (A) the larvae were bathed for 2 hours in stock WSSV suspension, in which the solution was diluted for 150 times; treatment (B) the larvae were bathed for 2 hours in stock WSSV suspension, in which the solution was diluted for 15000 times; C as control, without WSSV. For crablet stage the WSSV infection was done by feeding them with tiger shrimp which infected by WSSV. ANOVA used to analyze the different effect of infection treatment, i.e. diluted 150x, 15000x, and control to survival rate, then continue DMRT test in 5% level. T test used to compare two treatments i.e. infection treatment with feed and without infection. PCR method used to detect WSSV of infection in zoea-1, zoea-3 and crablet stages. The results showed that for zoea-1 and zoea-3 stage, increasing concentration virus showed significant difference respect, showed by decreasing of survival rate. In crablet stage the WSSV infection by feeding can decrease survival rate. In proving the dead of mud crab zoea-1, zoea-3 and crablet were due to the infection of WSSV, the PCR method was used. The result showed that look PCR product was revenged in the cell with size of band were as expractise. According to this result can be concluded that zoea-1, zoea-3, and crablet stages of tested mud crab were sensitive to WSSV infection.