Viral contamination of tiger shrimp Penaeus monodon broodstock in Bangladesh

Abstract

Stocking specific-pathogen-free (SPF) shrimp postlarvae (PL) has been reported to have much potential to enhance production by notably reducing the infection-driven mortality. In terms of SPF PL production in Bangladesh, except white spot syndrome virus (WSSV), several potential viruses such as hypodermal and hematopoietic necrosis virus (IHHNV), monodon baculovirus (MBV), hepatopancreatic parvovirus (HPV), and yellow head virus (YHV) which may synergistically cause mortality are ignored. Therefore, this study aimed to investigate the viral contamination in hatchery-brood-shrimps in Bangladesh as the broods horizontally and/or vertically transfer the viruses to their offspring. Five randomly selected representative hatcheries were investigated over 3 months (January to March) to know the status of viral contamination. Broods in all the hatcheries were found to be contaminated with WSSV, IHHNV, MBV, HPV, and YHV. The results showed that the prevalence of WSSV, MBV, HPV, and YHV did not significantly differ between hatcheries. The highest (72%) and the lowest (30%) prevalence of MBV and WSSV, respectively, were recorded in January. In February, the highest (81%) and the lowest (28%) prevalence were found in MBV and HPV, respectively, where the highest and the lowest prevalence were 88% and 40% for IHHNV and HPV, respectively, in March. The prevalence of IHHNV and MBV were not significantly different. The relative prevalence of WSSV, HPV, and YHV were significantly low compared with that of IHHNV and MBV. Notably, increasing water temperature from January (22 ± 0.71 °C) to March (27 ± 1 °C) increased the prevalence of all the viruses and subsequently the extremity of infection. The contamination in broods forwarding to the production of multiple-virus-contaminated PL is considered as an obstacle to higher production of shrimp at farm level in Bangladesh. Hence, the present study suggests focusing on the deleterious-virus-free shrimp broods in commercial shrimp hatcheries in Bangladesh.