大黄鱼库道虫病的初步研究

Discovery and Preliminary Studies of Kudoasis of Large Yellow Croaker, Pseudosciaena crocea (Richardson )

在广东湛江海水网箱养殖的大黄鱼 (Pseudosciaenacrocea)中发现了库道虫病 (Kudoasis) ,检出率高达 31%。其症状表现为 :白色孢囊分布于胸鳍、腹鳍、臀鳍和尾鳍等的鳍膜下 ,剖检时发现腹壁和背部肌肉中布满许多白色呈球形或椭圆形的小孢囊 ,在肠系膜、腹膜以及近口腔的粘膜上也有大量的白色小孢囊分布。镜检发现孢囊中含有典型的库道虫 ,其孢子宽为 ( 8 90± 0 55) μm ,长为 ( 8 35± 0 4 6 ) μm ,极囊宽为 ( 2 39± 0 36 ) μm ,极囊长为 ( 4 4 8± 0 39) μm。孢子在淡水中 2 0min后全部死亡 ,在盐度为 6的水体中 ,12h和 2 4h后存活率分别约为 87.4 %和 70 % ;在盐度为 16、2 6和 36的水体中 ,孢子存活率均为 10 0 % ;在盐度为 4 6的水体中 ,12h和 2 4h后存活率分别约为92 %和 84 %。孢子对低温有较强的耐受力 ,当水温达到 4 4℃时 ,8h、12h和 2 4h后 ,孢子的存活率分别约为 91%、80 .5%和 6 6 %。

The kudoasis of maricultured large yellow croaker (Pseudosciaena crocea ) in Zhanjiang was first discovered and morbidity is as high as 31%. The symptoms of the diseased fish were as follows: white sporosac appeared under fin membrane at pectoral fin, pelvic fin, anal fin and paddle fin, and existed in abdominal and dorsal muscles, as well as on peritoneum, mesenterium and mucosa near oral cavity while anatomized. The typical characters of spore were observed under light microscope. The width and length of spore were (8.90±0.55) μm and (8.35±0.46) μm respectively, the width and length of polar capsule were about (2.39±0.36) μm and (4.48±0.39) μm separately. All spores in freshwater for 20 min died, the survival rates of spore in salinity of 6 for 12 h and 24 h was 87.4% and 70% respectively, in salinity of 16, 26 and 36 water for 24 h were all 100%, but in salinity of 46 water for 12 h and 24 h were 92% and 84% respectively. The spore had higher tolerance against low temperature, but the survival rate was 91%, 80.5% and66% respectively when the water temperature kept 44 ℃ for 8 h, 12 h and 24 h.