Host range, specificity, and virulence of Steinernema feltiae, Steinernema rarum, and Heterorhabditis bacteriophora (Steinernematidae and Heterorhabditidae) from Argentina

Infections were carried out in the laboratory to determine the host range, specificity, and virulence of Steinernema rarum, S. feltiae, and Heterorhabditis bacteriophora that were isolated from different regions of Argentina. All insect orders showed a remarkable susceptibility to the three nematode species, showing mortality values higher than 66%, except for Anoplura. The mortality of the insects of agronomic interest was more than 90%. As for insects of sanitary importance, S. feltiae and S. rarum caused 60% of mortality, whereas H. bacteriophora caused 80%. The results fluctuated when considering the buccal apparatus function of the insects. Nematodes completed their cycle in anoplurans, orthopterans, lepidopterans, and hymenopterans, while the development varied in coleopterans, homopterans, hemipterans, and dipterans. S. rarum developed completely both in immature and adult, while S. feltiae and H. bacteriophora developed preferably in immature. The three isolates are capable of parasitizing a wide host range under laboratory conditions; H. bacteriophora is more virulent than the evaluated Steinernema spp. against Galleria mellonella larvae; the pathogenicity and specificity depend on the bioecological characteristics of nematodes and hosts. (C) 1999 Academic Press.