Effect of \u3ci\u3eBaculovirus penaei\u3c/i\u3e on Growth and Survival of Experimentally Infected Postlarvae of the Pacific White Shrimp, \u3ci\u3ePenaeus vannamei\u3c/i\u3e

Abstract

In a series of experiments conducted to investigate age and size-dependent effects of the baculovirus BP on postlarvae of the Pacific white shrimp, Penaeus vannamei, six groups of specific pathogen-free shrimp of different ages (mysis 2–3 through PL 25) were exposed to the virus and cultured for 15 to 21 days. All BP-exposed groups of early postlarvae (PL 9 or younger) became heavily infected within 2–5 days of initial exposure to the virus, and some of those groups experienced high mortalities compared to the noninfected controls. Postlarvae that survived the infection had highly variable and significantly reduced growth, as determined by dry weight, compared to controls. Exposure of older postlarvae to BP produced a high prevalence of infection but with little effect on either survival or growth. One group of shrimp exposed to BP at PL 9 was cultured for 49 days. Postlarvae that survived the infection were significantly smaller than the noninfected controls for the first 4 weeks following exposure to the virus; however, the effect of BP on long-term growth of infected postlarvae appeared minimal. To determine the effect of BP on nutritionally stressed shrimp, groups of noninfected and previously infected postlarvae (PL 13–14) of similar size were deprived of food for 10 days. Less than 2% of the infected postlarvae survived the 10-day starvation period compared to 52% survival of the noninfected postlarvae