中国南部池养幼鲩寄生鱊头槽绦虫的种群动态

摘要

The population dynamics of Bothriocephalus acheilognathi, a parasite in juvenile grass carp Ctenopharyngodon idellus (C. et V.) raised in a fish pond in South China, was studied in 1986, l987 and 1998. The tapeworm population in age 0 and over-wintering age Ⅰ grass carp followed an annual cycle from its establishment to its decline, whereas age Ⅱ commercial-sized fish was not affected. A high level of prevalence in winter led to a peak in early spring at 20.4 ℃ and a high level of mean intensity in the following months. When uninfected 0 group (1986) and age Ⅰ juvenile (1987) grass carp were introduced into the pond which kept the infected over-wintering grass carp, their prevalence reached 93.1% and 96.9% respectively one month after infection. The prevalence of the tapeworm in over-wintering and newly infected juvenile grass carp declined sharply in August and September at 28～33℃ and rose again to a minor peak in October. The mean intensity of 243.9 worms was observed in July. Cestode dispersion (S2/) for 1986 and 1987 was > 1 from April to October. In the population structure from April to August, young worms < 1 cm dominated, maintaining 97.2%～98.2%. In November, the number of young worms decreased with the appearance of large-sized gravid worms, which either vanished or remained in small numbers in December. The above findings provide a feasible basis for the control of bothriocephaliasis epizootics.%本项目研究池塘养殖的鲩(草)鱼体内寄生的(鱼矛)头槽绦虫(B. acheilognathi)的种群动态.于1986、1987和1998三年内分别观察0、Ⅰ龄幼鲩及Ⅱ龄商品鲩感染的情况.0龄及Ⅰ龄越冬鲩的绦虫种群由初染至收敛周期为1年,Ⅱ龄鲩不感染,冬季高感染率导致早春水温在20.4℃的感染高峰,感染强度持续数月,6月达到243虫/鱼.未感染的0及Ⅰ龄幼鲩在2、3月分别引进放养感染了的越冬Ⅰ龄鲩的池塘.1个月后,感染率达到93.1%～96.9%,8至9月感染率迅速下降,10月又稍升高.1986和1987年的4～8月,绦虫的分布(S2/X)>1,为聚集分布,体长<1 cm的幼虫在种群结构中占优势,为97.2%～98.2%,11月幼虫数目下降,大孕节绦虫随之出现,12月大孕节绦虫仅少数存留或全部消失.试验结果为消灭鲩鱼绦虫病提供了可靠依据.