Postembryonic Ventral Nerve Cord Development and Gonad Migration in Steinernema carpocapsae.

Steinernema carpocapsae is an entomopathogenic nematode widely studied for its properties as a biocontrol agent in insect pest management and as a model for understanding bacterial symbioses. Less attention has been given to the development of specific anatomical structures within S. carpocapsae. A better understanding of entomopathogenic nematode development and anatomy may lead to improved biocontrol efficacy. We recently demonstrated that the neuroanatomy of S. carpocapsae IJs differs from the dauer stage of Caenorhabditis elegans. Here, we used in vitro cultures of S. carpocapsae to examine the early development of the ventral nerve cord (VNC). Similar to C. elegans, S. carpocapsae hatches as a J1 with a VNC containing only a fraction of the neurons found in later developmental stages. During J1 development, S. carpocapsae adds additional cells to the VNC to establish the complete set of neurons. During our examination of the VNC, we also noted variable gonad arm development among S. carpocapsae individuals. Using synchronized in vitro cultures, we found that the gonad migration pattern in S. carpocapsae was distinct from both C. elegans and the Diplogaster nematode Pristionchus pacificus. The S. carpocapsae gonad arm migration was highly variable.