ABSTRACT: Bacteria from Steinernerna scapterisci were isolated and cultured in the laboratory either in vivo or in vitro and collected from two field locations. The bacteria were identified by gas-liquid chromatography of their fatty acid methyl esters using the MIDI Microbial Identification System. The bacteria clustered into three groups. All but one strain in one group were identified as Ochrobactrum anthropi, the odd strain was identified as Paracoccus denitrificans. A second group was identified as Xanthomonas maltophilia. A third group, although identified by the MIDI system as different genera and species, were shown by dendrogram cluster analysis techniques to be in the same genus and perhaps divided into four species. We consider all members of the third group to be in the genus Xenorhabdus.

Development, Reproduction, and Pathogenicity of Steinemema scapterisci in Monoxenic Culture with Different Species of Bacteria

ABSTRACT: Associations between steinernematid nematodes and their symbiotic bacteria are of fundamental importance. The reported bacterial symbionts of all species of Steinernema are in the genus Xenorhabdus. This paper reports on the development, reproduction, and pathogenicity of infective juveniles of Steinernema scapterisci produced on bacteria other than Xenorhabdus spp. The nematode developed and reproduced on a number of bacterial species, including Escherichia coli, Ochrobactrum anthropi, Paracoccus denitrificans, Pseudomonas aureofaciens, Pseudomonas fluorescens Biovar B, Xanthomonas maltophilia, Xenorhabdus nematophilus, and Xenorhabdus spp. Although adult development occurred on all bacterial species, progeny production after 14 days was significantly greater on X. nematophilus and P. fluorescens Biovar B than on the other bacterial species. Infective juveniles which were produced on 0. anthropi, P. denitrificans, P. aureofaciens, and X. nematophilus caused equal mortality to the southern mole cricket, Scapteriscus borellii. Since Xenorhabdus spp. is reported to change from a primary phase to a secondary phase with reproduction being considerably less on the secondary phase, and since the nematodes were equally pathogenic when produced on other bacteria, it may be more efficient to produce the nematode on bacteria other than Xenorhabdus rather than contend with phase variation.

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