Possible integration of beneficial nematodes and microbial agents for biocontrol of soil pests

Since soil ecosystems are constructed of complex biological webs, it has been generally difficult to control soil pests with a single biological agent. Combinations of two or more agents tend to compensate each other for any deficiency or may have a synergistic effect. This paper discusses the possibilities of the integrated control of soil pests by the following combinations of biological agents: 1) Entomopathogenic nematodes with different searching strategies against two or more target insects. 2) Entomopathogenic and fungivorous nematodes against insect pests and soil-borne fungal diseases. 3) Entomopathogenic nematodes and microbial agents, such as Bacillus thuringiensis (Bt) or Pasteuria penetrans (Pp), against one target insect and plant parasitic nematodes. 4) Fungivorous nematodes and microbial agents, such as Pp, against soil fungal diseases and plant parasitic nematodes. 5) Beneficial nematodes and microbial agents against insect pests, fungal diseases, and plant nematodes. For the actual practice, discussions will be made on the following issues: 1) Compatibility of the employed bioagents with other agents. 2) Sensitivity of one biological agent to the additives or activators employed for the other. 3) Optimum temperature range for combined application. 4) Persistence of the employed agents in soils.