蜕皮与中国对虾仔虾肠道杆菌病及肠道堵塞的关系

RELATIONSHIP BETWEEN MOLT AND INTESTINAL BACILLOSIS AND INTESTINAL OBSTRUCTION OF POST LARVAE OF PENAEUS CHINENSIS

于1996年5月，在青岛市红岛镇后阳育苗场，采用饲养实验的方法对患肠道疾病的中国对虾仔虾的康复进行观察研究。结果表明，中国对虾仔虾的某些肠道疾病的康复与蜕皮存在极为密切的关系。肠道杆菌病对对虾状幼体和糠虾幼体危害极大，患病个体死亡率为100％，而患该病的仔虾幼体却有较高的存活率（32％），存活者多数为病症出现时已处蜕皮前期的个体，而在蜕皮间期开始患病的个体极少能发育至蜕皮变态。肠道堵塞是仔虾期幼体的常见病，因个体体质的差异和环境条件的不同，幼体的存活率也有差别，蜕皮前期开始患病的幼体，其存活率（73．3％）远远高于蜕皮问期开始患病的幼体的存活率（15％）。

Intestinal bacillosis of some post larvae of Penaeus chinensis occurred in some breeding tanks at Houyang Hatchery, Hongdao Town, Qingdao in May 1996. So did the intestinal obstruction in other breeding tanks. The recovery of diseased post larvae was observed after some measares were taken which included the improvement of the water quality, feeding more of larvae of brine shrimp, applying anhbiotic and disinfect dosape. Meanwhile, the diseased post larvae were selected and bred in beaker. Their behaviors of feeding, excrement exhaushng and molting were observed, together with the amount and moving of fbod and bacterium block within their guts. There is a dishnct relationship between the molt of shrimp and the recovery of post larvae of Penaeus chinensis from alimentary canal disease. The inteshnal bacillosis was extremely harmful to larvae of shrimp, the mortality of diseased zoea and mysis larvae is 100%, but that of diseased post larvae is about 68%. Most survivors are those which are at the premolt stage when the symptoms appear, with a sunival rate of 68%. Few larvae infected at the intermolt stage could complete their subsequent molt and the survival rate is only 7%. Inteshnal obstruction is of ten observed at the post larvae stage. The sorival at of the infected larvae varies in response to their physique state and environmnt conditions. The smeival rate of the larvae infected by inteshnaI obstruction at the premolt stage are higher than those at the intermolt stage. Most of the larvae infected by intestinal obstruction at the premolt stage could molt successfully, and the survival rate is 73.3%. only few diseased post lareae infected at the intermolt stage could complete molt, and the surival rate is only 15%. Hence, a key to the recovery of diseased post larvae is their molting. The post larvae can survive only when they undergo a process of molt. Thus, the survival rate of diseased Post larvas could increase if centain measures are taken to prolong the larvae survival time to complete their molting, such as improving the state of lareae health and water quality, applying more living feed, using disinfect dosage and anhbiohc properiy.