长江丽棘虫种群生态的研究

长江丽棘虫（ＢｒｅｎｔｉｓｅｎｔｉｓｙａｎｇｔｚｅｎｓｉｓＹｕｅｔＷｕ，）隶于棘吻目，长棘吻科，是余仪，伍惠生在长江中游的鱼中采获并定为新种［１］。据他们调查，长江中游有１４种经济鱼类是该种棘头虫的终末宿主，黄颡鱼是终末宿主之一。有关这种寄生蠕虫的种群生物学研究尚未见到报道。１　材料和方法从１９９８年６月至７月中旬，随机购得渔民在江边捕获的黄颡鱼７６尾。在实验室内逐一测量黄颡鱼的全长、体长，称其重量，剖开鱼腹，完整地取出消化道，称鱼的空壳重，逐一解剖检查鱼的胃和肠道，记录检出的寄生蠕虫数量和寄生…

Studies on the Population Ecology of Brentisentis yangtzensis

Total number of 76 Pseudobagrus fulvidraco (Richardson) caught in Huangzhou along the Yangtze River from June to July in 1998 were examined for infection by Brentisentis yangtzensis . The infection rate of the host was 30.3% and the intensity of infection was 60. The infection rate of female host was higher than that of male,but the difference of parasite intensity between female and male host was not significant. The parasite intensity of the host with body length within 23cm increased notably with increasing of the body length,but the parasite intensity of the host with body length above 23cm decreased rapidly and no Brentisentis yangtzensis was found in the host with body length above 31cm. Distribution of Brentisentis yangtzensis was clumped in the host population. The 90.3% of the parasite was distributed in first 1/3 intestinal portion of the host. The population structure pattern of the parasite looked like a pyramid. The parasitism did not cause obvious difference of condition factor in the hosts.