Parasitic Infection in the Freshwater Snails, Pila ovata and Lanistes varicus (Gastropoda: Ampullariidae)

Abstract

A total of 1181 freshwater ampullarid snails (apple snails) comprising 973 Pila ovata and 208 Lanistes varicus were examined for parasitic stages. These snails were collected from fourteen locations in Bayelsa, Edo and Delta states. Pila ovata was the more abundant apple snail in the study areas. Ninety (9.3%) of the Pila ovata and 23 (11.1%) of Lanistes varicus were infected with parasitic stages. Infection rates in the snails from the various sampling locations showed a least value of 1.7% and the highest value of 16.9%.  The same types of parasitic stages were isolated from both species of apple snails and included ciliates, nematode larvae, sporocysts, rediae and cercariae. Two types of cercariae, xiphidiocercariae and amphistome cercariae, were isolated from the snails. However, the two types of cercariae did not occur in the same snail host. Further investigations are on to obtain adult stages of the parasites from in vivo cultures for identification of the parasites.