SEASONAL CHANGES IN THE OCCURRENCE AND MATURATION OF THE NEMATODE PROCAMALLANUS FULVIDRACONIS IN THE YELLOWHEAD CATFISH PEL TEOBAGRUS FULVIDRACO IN LIANGZI LAKE OF HUBEI PROVINCE,CHINA

Seasonal dynamics of the occurrence and maturation of Procamallanus fulvidraconis in its definitive host,Pelteobagrus fulvidraco(Richardson), were investigated in Liangzi Lake,Hubei province during February 2001 to July 2002. A total of 900 fish were collected,The results indicated that the prevalence of P. fulvidraconis was higher than 90% in each month with only an exception(32%) in January 2002. No significant difference was found between the prevalence in different months(G=16.9620.0517= 27158). Mean abundance of the parasite was more than 6.32 in almost all months,except for a low level of 0.46 in January 2002. Statistical analysis showed that changes in mean abundance of the parasite were significantly seasonal(F=12.58>F0.0117,882= 1.98). The adult female P. fulvidraconis was divided into three developmental stages, i.e. mature stage(adult without eggs),ungravid stage(with eggs) and gravid stage(with larvae). The present investigation found that the female in mature stage reached the peak level of infection in February and March,female in ungravid stage had highest level in May to July, and those in gravid stage reached highest level in June to September. Each stage of female and male had one annual peak of infection. In might suggest thatP. fulvidraconis had a yearly cycle. The developmental time of the female in each stage were supposed to be that about 5-6 months from the first-stage larvae to mature stage, 4-5 months from mature to ungravid stage and 1-2 months from ungravid to gravid stage