Ecological considerations in the biological control of soil-inhabiting insects with entomopathogenic nematodes

Entomopathogenic nematodes in the families Steinernematidae and Heterorhabditidae are undergoing intense scrutiny as biological alternatives to chemicals for suppression of soil-inhabiting insects. Although naturally adapted to the soil, these nematodes are currently not as predictable or effective as chemical agents. Efforts to close or narrow this efficacy gap have been directed toward technological solutions, with striking advances being made recently in nematode mass rearing, shipping, storage, formulation and genetic improvement. Our understanding of entomopathogenic nematode soil ecology has not kept pace. In particular, we are unable to predict nematode behavior in the soil, biotic interactions with soil antagonists remain virtually unstudied, and the abiotic conditions optimal for survival and mobility are insufficiently understood. There is a compelling need for a standardized protocol that would permit cause and effect relationships to be established for successful and unsuccessful field trials. Fundamental to the applied use of entomopathogenic nematodes is gaining insight into nematode interactions with environmental parameters that determine the likelihood and outcome of nematode-insect encounters.