ABSTRACT
This chapter examines factors affecting the movement of steinernematid and heterorhabditid nematodes in soil. Soil, the natural habitat for entomopathogenic nematodes, varies greatly in chemical composition and physical structure. Phytonematologists have long recognized the importance of the soil environment on plant-parasitic nematodes so a number of reviews elucidating soilnematode interactions are available. Soil texture, a basic concept in soil science, is determined by the ratio of particle types, which are divided into three arbitrary fractions based on size: sand, silt, and clay. Studies on factors affecting nematode survival or persistence in soil have focused on moisture, temperature, and parasites and predators. Soil texture affects survival of the steinernematids S. carpocapsae and S. glaseri. In nonsoil laboratory studies, S. carpocapsae can survive with oxygen tension as low as 0.5% of saturation at 20°C. Oxygen is replaced by diffusion from the atmosphere into the soil pores; carbon dioxide diffuses from the soil pores to the atmosphere.
