Performance of WSSV-infected and WSSV-negative Penaeus monodon postlarvae in culture ponds.
In a survey of 27 Penaeus monodon culture ponds stocked with postlarvae (approximately PL10) at medium density (approximately 40 shrimp m(-2)), single-step nested white spot syndrome virus (WSSV) PCR was used to measure the WSSV infection rates in the shrimp populations within 1 mo after stocking. Seven ponds were initially WSSV-free, and the shrimp in 5 of these were harvested successfully. In the ponds (n = 6) where detection rates were higher than 50%, mass mortality occurred during the growth period, and none of these ponds was harvested successfully. In a subsequent study, P. monodon brooders were classified into 3 groups according to their WSSV infection status before and after spawning: brooders that were WSSV-positive before spawning were assigned to group A; spawners that became WSSV-positive only after spawning were assigned to group B; and group C consisted of brooders that were still WSSV-negative after spawning. WSSV screening showed that 75, 44 and 14%, respectively, of group A, B and C brooders produced nauplii that were WSSV-positive. Most (57%; 16/28) of the brooders in group A produced nauplii in which the WSSV prevalence was high (>50%). When a pond was stocked with high-prevalence nauplii from 1 of these group A brooders, an outbreak of white spot syndrome occurred within 3 wk and only approximately 20% of the initial population survived through to harvest (after 174 d). By contrast, 2 other ponds stocked with low-prevalence and WSSV-negative nauplii (derived respectively from 2 brooders in group B), both had much higher survival rates (70 to 80%) and yielded much larger (approximately 3x by weight) total harvests. We conclude that testing the nauplii is an effective and practical screening strategy for commercially cultured P. monodon.
Peng
S E
SE
Department of Zoology, National Taiwan University, Taipei, ROC.
Lo
C F
CF
Lin
S C
SC
Chen
L L
LL
Chang
Y S
YS
Liu
K F
KF
Su
M S
MS
Ko
G H
GH
D000818:Animals; D017756:Aquaculture; D004267:DNA Viruses / Q000235:genetics / Q000302:isolation & purification*; D004279:DNA, Viral / Q000032:analysis*; D004196:Disease Outbreaks / Q000662:veterinary; D007814:Larva; D009865:Oocytes / Q000821:virology*; D033561:Penaeidae / Q000254:growth & development / Q000821:virology*; D016133:Polymerase Chain Reaction / Q000662:veterinary; D015995:Prevalence; D015203:Reproducibility of Results; D012098:Reproduction; D012680:Sensitivity and Specificity; D016019:Survival Analysis
D004279:DNA, Viral