Population Dynamics of Melanopsis praemorsa [(L., 1758) (Thiaridae)] Snails in Yarmouk River, (Jordan) and Its Seasonal Infection with Larval Trematodes PDF

Keywords

snails, Jordan, Larval trematodes

Abstract

A total of 5600 Melanopsis praemorsa (L., 1758) snails were collected from two stations near El-Maqaren at Yarmouk River, Jordan during the period from May 1982 to March 1984. Of these 6.04% were infected with Larval trematodes which included nine different types of cercariae: Cercaria melanopsi I through VII, a tail less cercaria, and Cercaria levantina 5. Overall infection rates of M. praemorsa with larval trematodes varied seasonally and three peaks have been observed. The first was during September-October, the second during January, and the third during May-June. The most abundant type of larval trematodes was the tail less cercaria and exhibited the same seasonality as the total infection. The appearance of young snails (3-6 mm long) during July 1983 may indicate that M. praemorsa produces at least once a year. The heavy rains and flooding during February 1983 has drastically affected the snail population at one of the stations. The relationship between the density of snails and the infection rates with larval trematodes is discussed.