Rachanee Chotikachinda, Amornrat Phongdara, Jareeporn Ruangsri, and Kitjakarn Supamattaya

pp. 199 - 214

Abstract

MBV infection in various stages of Penaeus monodon were studied. In hatcheries, MBV infection was
detected early in nauplii stage using PCR technique, whereas rates of infection of 11.15-49.50% were observed
in PL1 using histological technique, rising up to 15.26-100% in PL 10. In earthen ponds, the infection in PL15
was initially in the range of 68.68-96.00%. The infection was decreased toward the end of the first, second
and third month of rearing period ranging between 13.63-54.83%.
The laboratory trial showed that types of feed might affect the rate of MBV infection of larvae.
Postlarva fed with artemia showed lowest infection rate at 29.41±7.98%, whereas the infection rates of
shrimp fed with minced cockle flesh and commercial feed were 39.09±12.08% and 52.81±11.91, respectively.
In stress test trial, a significant MBV infection was detected in the group of larvae that were raised with 25ºC and 34ºC and the salinity at 6 ppt and 18 ppt for 12 hours then rearing in normal condition for 3 days. In the
24 hour-stress trial, and transferred to normal condition for 7 day, the groups that were exposed to stress
conditions had significantly higher rates of infection than the control group (p<0.05). The 24 hour - transportation condition resulted in highest MBV infection rate (73.61±1.25%).
From the present study, it was concluded that MBV infection in larvae from hatcheries increases
with period of rearing and stress exposure, but the infection tended to decreased with rearing period in
earthen pond condition. Proper feeding management and prevention of stress conditions could reduce of
MBV infection in black tiger shrimp.