| 1. In this study, copepoda and its resting eggs in shrimp culture ponds were detected using PCR dot-blot hybridization and nest-PCR for the presence of WSSV. The results showed that WSSV positive cases were detected in copepoda from egg to adult, and the positive copepoda appeared earlier than cultural shrimp in ponds. It may suggestted that copepoda was a WSSV host and transmission medium, and there may exist the transmission routes of WSSV through the resting eggs over winter.2. In addition, a kind of copepoda (Acartia clausi) was experimentally cultured, which from the resting eggs separated from the pond mud, then the cultural conditions and biological characters were partly mastered. A mass of copepoda were purely cultured to provide material for further studies.3. To testify whether WSSV could spread through copepoda to shrimp, two groups of adult copepoda were infected by two methods, soaking and feeding respectively, and fed to Litopenaeus vannamei using the copepoda carring WSSV. Soaking method didn't work to spread WSSV to copepoda, while feeding method worked obviously, and in feeding experiment, nearly all shrimps were decteted WSSV positive by nest-PCR method. It showed adult copepoda could carry active WSSV particle and led to shrimp infection potentially. In addition, positive cases were also detected in the samples of the resting eggs and nauplii of copepoda, which indicated it was extremely possible WSSV could be vertically transmitted over winter by the resting eggs of copepoda.4. From the experiments, we might conclude that adult copepoda could carry WSSV and then infected shrimp through feeding, and that the resting eggs might be a kind of potential transmission medium to lead to WSSV transmit in different generations. Therefore, traditional shrimp culture should be reformed according to the WSSV transmission routes. Finding a method to kill out the resting eggs of zooplankton in shrimp pond may be in favor of the prevention of WSSV infection.
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