An improved solid medium-based culturing method for Steinernema hermaphroditum.

Steinernema hermaphroditum is the only identified entomopathogenic nematode that is consistently hermaphroditic and thus offers a great opportunity to use genetic approaches to probe symbiosis. Evolutionarily, ecologically, and morphologically distinct from laboratory nematodes commonly used in the laboratory, with both forward and reverse genetics tools available, this species also provides an opportunity to explore other areas of biology, especially using comparative studies. Here, we describe an improved solid medium-based culturing method for S. hermaphroditum that we found particularly helpful for phenotypic analysis and genetic manipulation. We document the rapid increase in the size of the worm; and show that the uniform growth of the worm on this medium provides a good basis for developmental studies. Finally, we measure the brood size of individual animals, which, although far larger, has a very similar trajectory to that of the hermaphroditic Caenorhabditis elegans, suggesting common reproductive restraints.