Ecological Analysis of the Helminth Fauna in Natrix tessellata (Reptilia, Colubridae) from the Low Volga Region (Russia)

An ecological analysis of the helminth fauna of the dice snake Natrix tessellata from different habitats of Astrakhan oblast was carried out in 2004, 2005, and 2008. The helminth community of the reptile included 21 species of parasitic worms: 11 trematodes, 1 cestode, 8 nematodes, and 1 acanthocephalan. Of these, 11 species were found in all the studied localities and form the bulk of N. tessellata helminth fauna. Dominant and subdominant helminth species were found in snakes in all habitats as a result of the implementation of its main trophic relationships. A comparison of the helminth composition from different study sites showed a relatively high degree of similarity. Differences in the helminth fauna of the dice snake from different habitats were insignificant and related to rare and accidental parasite species. Significant differences in the infection level of snakes with certain species of helminths were revealed. Most of the helminth species that parasitise the dice snake have a complex life cycle. The helminth infection of reptiles was determined to a large extent by biotic factors: fauna and the number of invertebrates (intermediate hosts of helminths) and vertebrates (paratenic and final hosts) in the biocenosis.