Molecular identification, phylogeny and phylogeography of the entomopathogenic nematodes of the genus Heterorhabditis Poinar, 1976: a multigene approach

Abstract

Summary Presently, the genus Heterorhabditis contains 16 valid entomopathogenic nematode species. In this study we used samples from 11 species: H. amazonensis, H. bacteriophora, H. baujardi, H. beicherriana, H. downesi, H. floridensis, H. georgiana, H. indica, H. megidis, H. noenieputensis, and H. zealandica to amplify and sequence five gene fragments: the D2-D3 expansion segments of 28S rRNA, ITS rRNA, COI mtDNA genes and unc-87 and cmd-1 genes encoding thin filament (F-actin)-associated protein and calmodulin, respectively. Fifty new sequences for 11 species were generated. More than 980 sequences of five genes were analysed. Phylogenetic and sequence analysis of these genes using Bayesian inference, maximum likelihood and statistical parsimony confirmed a division of the genus into three clades (groups): ‘Indica’, ‘Bacteriophora’ and ‘Megidis’. The analysis of gene sequences downloaded from GenBank and identified as Heterorhabditis revealed many cases of species misidentifications and presence of reading mistakes in some sequences. Synonymisation of H. somsookae with H. baujardi, H. gerrardi, H. pakistanensis with H. indica, and H. sonorensis with H. taysearae, are confirmed by sequence and phylogenetic analysis. The ITS rRNA and COI genes could be considered as informative markers for species identification, barcoding and phylogeographical studies of Heterorhabditis.