Genomic analysis of the entomopathogenic nematode Steinernema hermaphroditum

Entomopathogenic nematodes (EPNs) of the genera Steinernema and Heterorhabditis parasitize and kill insect hosts, making them promising tools of natural insect control; at the same time, these EPNs also have species-specific mutualistic intestinal bacteria, making them instances of symbiosis as well as of parasitism. Most EPNs are genetically difficult to study, either because of awkward life cycles, or because they have heterozygous male-female genetics which cannot easily be made homozygous for efficient mutagenesis or transgenic modification. Steinernema hermaphroditum is a valuable exception because it has primarily self-fertilizing hermaphrodites with rare males, much like the model nematode Caenorhabditis elegans, and therefore can be subjected to efficient genetic modification. To develop S. hermaphroditum as a new model organism for both EPNs and bacterial symbiosis, we have assembled and analyzed a chromosomally-scaffolded genome from the wild-type reference strain PS9179.