Haplotype diversity of Steinernema feltiae (Nematoda,Steinernematidae) in Eurasia

Phylogenetic analysis of ITS rDNA sequences of the entomopathogenic nematode Steinernema feltiae Filipjev, 1934 (Wouts, Mráček, Gerdin and Bedding, 1982) was used to infer intraspecific genetic variability of this rhabditid nematode. Nucleotide intraspecific differences among S. feltiae isolates reached the level of 19 base pairs per ITS rDNA region, i.e. up to 2.9%. Several weakly or moderately supported intraspecific clades were detected. Sicilian and Swiss isolates of S. feltiae were found clustering together. Swiss strain ‘St. Bernard’ has been isolated on the St. Bernardino mountain pass in Switzerland in 2000. Phylogenetic relationships among S. feltiae isolates were inferred by using three different methods (maximum parsimony, neighbor joining and maximum likelihood). The topologies of the phylogenetic trees were identical and thus only ML tree is presented. ML tree revealed that S. feltiae isolates from Israel and Armenia grouped at the basal position of the tree, while in the spanning network obtained with POPART software, Iranian and Ukrainian isolates were the closest to the outgroup. In all methods of analyses, the European and Siberian strains of S. feltiae occupied terminal positions. Thus, further studies on the intraspecific genetic variability of entomopathogenic nematodes is needed.