Efficacy of Doob grass, Cynodon dactylon against white spot syndrome virus in Penaeus monodon

Abstract

White spot syndrome virus (WSSV) has been considered one of the deadliest pathogens of penaeid farmed shrimp. A doob grass, Cynodon dactylon was tested against deadly white spot syndrome virus Penaeus monodon. The trial was to optimize the crude extraction and to mix the powder to the shrimp feed. The obtained formulation was tested against WSSV at a small scale in bioassay challenge laboratory, medium scale trial in cages and large-scale trial in the commercial ponds. The trial showed heat deactivates the active ingredient/s present in C. dactylon. The formulations using 150 g/kg of feed and 200 g/kg of Cynodon dactylon in feed gave 100% survival. Similar results were obtained in the cage trial. Large scale trials were conducted in 60 commercial ponds of the same size (area 5,000 m2 and depth 1.2 m), shape and locations. The treatment ponds' productivity was higher (12.7 ton/ha) than that of the control ponds (11.79 ton/ha). WSSV cases were not recorded in the control and treatment ponds. This study showed that C. dactylon extract has anti-WSSV properties and has no negative impact on shrimp growth.