Evaluating the persistence and effectiveness of entomopathogenic nematodes under laboratory conditions

Entomopathogenic nematodes (EPNs) are insect-parasitic organisms capable of killing their hosts, making them promising tools for use as biological control agents. Due to their safety for humans and potential compatibility with other methods of pest control, EPNs are well-suited for inclusion in integrated pest management programs. In fact, EPNs are now commercially produced and applied for the control of destructive pests, including western corn rootworm (Diabrotica virgifera virgifera). However, limited information is available regarding the persistence of applied EPNs and their interactions with the endemic EPN community in the soil following application. Therefore, this study was conducted to assess the effectiveness and persistence of two EPN species: Steinernema feltiae Oswego and Heterorhabditis bacteriophora ‘NY 04’ from Persistent Biocontrol under mesocosm conditions. Soil samples were collected from a depth of 20 cm at five different locations in a corn field and brought to the laboratory, with each location representing a separate block. Each block included six treatments: autoclaved soil with no applications; autoclaved soil with EPNs applied at 44.46 or 135.85 million/hectare; non-autoclaved soil with no applications; non-autoclaved soil with EPNs applied at 44.46 or 135.85 million/hectare. Subsamples of soil were collected from each treatment before and after EPN application, and baiting assays using Galleria mellonella larvae were conducted. Larvae suspected of EPN infection were placed on White traps to collect infective juveniles and confirm EPN species. The results of this study will help in understanding EPN persistence in the soil and interactions with endemic EPN communities under laboratory conditions.