CONICET | Buscador de Institutos y Recursos Humanos

Entomopathogenic nematodes (EPN)belonging to the Heterorhabditidae family are lethal parasites of soil-dwellinginsects. Two species were reported in Argentina: Heterorhabditis argentinensis and Heterorhabditis bacteriophora characterizedmainly by morphometric features. In this work a comparative andphylogenetic study between five Heterorhabditispopulations from Argentina was conducted to analyze the variability betweenstrains and to evaluate the taxonomic position of Heterorhabditis argentinensis. The PCA analyses of morphometric charactersseparated the larger juvenile, female and male H. argentinensis from H.bacteriophora populations. The juvenile (IJs) stage provided theclearest separation of Heterorhabditispopulations presenting the least variability between strains. The variable Land MBW were highly related to H.argentinensis IJs. Three groups were separated by this stage consideringPC1 and PC2: one formed by H.bacteriophora OLI, RIV and RN strains, (isolates from Córdoba and Río Negroprovince), one for H. bacteriophoraVELI strain (Buenos Aires province) and one for H. argentinensis (Santa Fe province). Heterorhabditis bacteriophora VELI and H. argentinensis isolated from regions with more rainfalls andhumidity presented larger values for morphometric features. Molecular analyses showed the Argentinean populations (H. bacteriophora VELI strain and H. argentinensis), forming a same clade, with six other H. bacteriophora populations (not from Argentina) with a geneticsimilarity between them of 99%. Heterorhabditisargentinensis presented one unique nucleotide that was not present in anyof the other species of the clade. Considering the results of this study H. argentinensis would be conspecific toH. bacteriophora, constituting astrain with a great morphometric variation where the host and climaticconditions could have influenced on the measurements.