The persistence of Steinernema feltiae (Rhabditidia:Steinernematidae) by adding host cadavers and sentinel hosts to greenhouse soil

Steinernema feltiae (Rhabditidia: Steinernematidae) is an entomopathogenic nematode that naturally occurs in the soil and is used in augmentive biological control programs for fungus gnats (Diptera: Sciaridae). Entomopathogenic nematodes rarely persist in the soil at population levels that offer adequate suppression of pest populations.  In small rearing operations, Galleria mellonella (Lepidoptera: Pyralidae), a large and very susceptible host, are used to rear entomopathogenic nematodes.  Once the nematode has gone through its life cycle, infective juveniles are collected, prepared in an aqueous solution, and applied to the soil as a drench. Infective juveniles are vulnerable to ultraviolet light exposure and desiccation until they make their way down into the soil. Instead of harvesting the infective juveniles from host cadavers, host cadavers can be placed on the soil surface allowing the juveniles to emerge directly into the soil. Alternatively, a sentinel host can be applied to the soil surface to increase the population of entomopathogenic nematodes already in the soil. I am conducting a three by two factorial design experiment, where entomopathogenic nematodes are applied to the soil as either a drench, host cadaver, or not at all is the first factor; and the additional of sentinel host (e.g. Galleria) to the soil or not is the second factor.  Soil samples will be collected and baited with Galleria to monitor entomopathogenic nematodes, and fungus gnat larvae will be monitored on a weekly basis using potato discs.  The objective of this experiment is to determine if fungus gnats can be controlled by simply placing host cadavers on to the soil, and if entomopathogenic nematodes populations can be increased in the soil by setting out sentinel hosts.