热带海洋珍珠贝类立克次体(RLO)病研究 Ⅶ 大珠母贝育苗期幼虫群体RLO病流行病学研究  

Studies on rickettsialike organism (RLO) diseaseof the tropical marine pearl oyster Ⅶ Epidemiological investigation of RLO disease in larvae populations of maricultured Pinctada maxima

作　　者：吴信忠[1] 潘金培[2] 江静波[3] 

机构地区：[1]中国科学院大亚湾海洋生物综合实验站,广东广州510301 [2]中国科学院南海海洋研究所,广东广州510301 [3]中山大学生命科学学院,广东广州510275

出　　处：《海洋学报》2002年第6期67-75,共9页

基　　金：中国科学院"八五"重点基金课题资助项目(KS85 121);国家重点基础研究发展规划(国家"973"计划)的部分资助项目(G1999012001).

摘　　要：对流行病学分析显示大珠母贝幼虫群体的死亡是以暴发性方式发生,从胚胎发育前期至变态期,幼虫存在两个死亡高峰,分别位于壳顶期之前或壳顶期和壳顶后期.大珠母贝幼虫群体的死亡率与RLO感染之间存在显著的相关性,在RLO感染的高峰之后均相应伴随幼虫群体死亡率的高峰,随着RLO感染率和感染强度的降低,幼虫群体死亡率也明显降低.在TEM下未发现未受精卵母细胞、受精卵和胚胎早期幼虫感染RLO,最先出现RLO包涵体阳性感染的时期为24h尚未摄食的D形期幼虫,故认为RLO可能不是通过垂直传播,而是通过外界接触感染的方式感染宿主,贝体感染至发病死亡存在潜伏期.The epidemiological investigations on the disease and death in mature eggs, embryonic developmental periods and larvae populations (6 h), Dshaped phase larvae (24 h), early umbo phase larvae, umbo phase in Luhuitou pearl oyster of Mariculture Farm of Sanya City, Hainan Province in April 1995 show that there are two peaks of mortality rates which occurred in early umbo phase or umbo phase and post umbo phase (Figs 1～3 and Table 1) respectively from preembryonic developmental periods to larvae phases. It indicates that the onset and death of Pinctada maxima larvae populations followed a pattern of outbreak. Between the prevalence, intensity of RLO infection and the mortality rates of larvae populations have obviously positive correlations. Generally, every peak of RLO infection is always followed by a peak of mortality rate of larvae hosts, and the mortality rates of larvae hosts declined with decrease of RLO infection (Figs 1～3). Under the transmission electron microscopy (TEM) no rickettsialike organisms were discovered in oocytes, fertilized ovum and early embryonic phase larvae (6 h). The RLO inclusions occurred first in the Dshaped phase larvae (24 h) under histological examination. Absences of RLO in transmission electron examination of oocytes of RLOinfected adult females, fertilized ovum and early embryonic phase larvae (6 h) indicate that RLO may not be transmitted transovarially. But RLO for host infection may be transmitted by contact transmission since RLO inclusions were first identified regularly in the Dshaped phase larvae (24 h), while these Dshaped phase larvae were still unable to take food furing hatching 24. In addition, the result of epidemiological investigation shows that no observable death occurred in the Dshaped larvae populations, but early obvious death occurred in larvae populations in the seventh day after fertilization, and the mortality rate is about 2180%. It indicates that there was a incubation period from RLO infection for host (Dshaped ph

关 键 词：大珠母贝 类立克次体病 流行病学 育苗期 幼虫 海水养殖 感染方式 

分 类 号：S944.46[农业科学—水产养殖]