Comparative Infectivity of Entomopathogenic Nematodes Against Wax Worms

Overview

This experiment compared the pathogenicity and reproductive success of six Steinernema nematode isolates—Steinernema carpocapsae, Steinernema adamsi, S. jefferhense, Steinernema ceratophorum, Steinernema surkhense, and Steinernema feltiae—using Galleria mellonella nymph, waxworm nymph, as the host organism. Galleria mellonella is used as a “lab rat” to the entomopathogenic nematodes due to their soft body, being large enough for easy infection, fast results, being inexpensive, well studied immune system, and susceptibility to the entomopathogenic nematodes’ venom. Each isolate was tested in six rounds, with three waxworms placed in individual Petri dishes and exposed to nematodes at a standardized concentration of 200 infective juveniles (IJs) per microliter. Waxworm mortality was monitored at regular intervals to determine how quickly each isolate could infect and kill the host. After host death, cadavers were held under moist conditions to allow for IJ emergence, and reproductive output was measured by counting the number of new nematodes produced per cadaver. Comparing mortality rates and IJ yields across isolates allowed evaluation of both virulence and reproductive efficiency. The results provide insight into how different Steinernema species vary in host-killing ability and life-cycle success under controlled conditions.