The infective juvenile (IJ) stage of EPNs penetrates the host insect through natural openings (mouth, spiracles, anus) or thin areas of the host’s cuticle. The IJs then release their mutualistic bacteria (Xenorhabdus spp. for steinernematid nematodes and Photorhabdus spp. for heterorhabditids) into the insect’s hemocoel. The mutualistic bacteria propagate and produce toxins and antimicrobial substances that kill the host in 48–72 h and protect the cadaver from colonization by other microorganisms. The nematodes initiate their development by using the food supplies provided by the bacterial biomass and the metabolized insect tissues and reproduce 1–3 generations depending on host size ( Hazir et al., 2003 and Lacey et al., 2015).