一种新的淡水等足类--细角鳃虫的寄生行为

珠江水系西江的局部支流近年出现了严重危害网箱养殖和江河鱼类资源的寄生虫病害,初步鉴定该虫隶属于甲壳纲、等足目、鳃虫科、细角鳃虫属(RocinelaLeach),是国内新发现的淡水鱼类寄生虫。文章就该虫对麦鲮的寄生行为进行了研究,结果表明:该虫具很强的寄生能力,240 min内累积感染率达90%。对寄生部位具一定的选择性,以寄生在鳃腔比例最大(55.5%),胸鳍基部(25.9%)次之。对麦鲮具较强的致死效应,23 h的累积死亡率为16.7%。吸血后体长(L)显著增长,而体宽(W)基本无变化。从寄主身上主动脱落的虫体,其L和L/W的增值比(%)均显著高于因使寄主致死而被动脱落的虫体(P<0.05);而仍在寄主身上的虫体,其L和L/W的增值比(%)则因各自摄食量的不同而存在较大差异。

Parasitic Behaviors of Rocinela sp.-a Newly Found Freshwater Isopoda

In recent years,serious epidemic caused by parasites had occurred in the west part of the Pearl Rivers,which had caused great damage on cage farming,and fish in the natural resources.The parasites had been preliminarily identified,belonging to Crustacea,Isopoda,Aegidae,RocinelaLeach.They were the newly found freshwater fish parasites in China.The authorused Rocinela sp.to carry on the study on parasitic behaviors to Cirrhina mrigala.The main results were summarized as follows: The parasites had very strong parasitic ability,the cumulative infection ratewas 90% in 240 min.The parasites had certain preferencefor parasitic locations of host fish,the gills ranked first(55.5%),followed by the bases of pectoral fins(25.9%).The parasites had strong lethal effects on host fish,after parasitized 23 h,thecumulativemortality was 16.7%.After the parasites sucked the blood of host fish,their length(L) was significantly higher than before,but their width(W) had no significant differences.Some parasites actively left the host fish,whose values of L and L/W increased significantly,the increment rates(%)were significantly higher than that of the parasites left passively,which caused Cirrhina mrigala died(P<0.05).There were some parasites that didn't leave host fish,but the scope of increment rates(%) of L and L/Wwas very big since the each different ingestion.