The three hosts of the Ligula intestinalis (Cestoda) life cycle in Lavernose-Lacasse gravel pit, France

The life cycle of Ligula intestinalis, a pseudophyllidean cestode, was stud ied in a South-Western French gravel pit. Copepods, fish and piscivorous bi rds, constitute the hosts necessary for complete parasite development. In o rder to determine the actual species likely to be responsible for the very high level of parasitism observed, a two-year study was carried out. Our re sults show that the copepod Eudiaptomus gracilis, the roach (Rutilus rutilu s) and the great crested grebe (Podiceps cristatus) were the most favourabl e hosts for continuation of the parasite life cycle. The study shows how al terations exerted by infective larval stages of L. intestinalis affect the population dynamics of roach.