Perspectives of non-phytoseiid predators for the biological control of plant pests

Non-phytoseiid mites of potential importance in the biocontrol of plant pests include a dozen families. The host plant constitutes the universe in which pests and predators interact; thus plant growth pattern, leaf structure and various available nutrients may affect the control potential of the mites. The role of infochemicals in prey finding by non-phytoseiids probably differs among the various families. Prey size may be important in control success when predaceous mites feed on insect pests. Interactions between phytoseiids and members of other families may hinder or complement pest control. Little is known of the effects of plant-protection chemicals on non-phytoseiid predators, but they appear to be quite variable. Current research onHemisarcoptes, a parasite of armored scale insects, is reviewed, including a successful introduction into New Zealand. Active mite slicing into host shields and deutonymph interactions with its vector-beetle are important aspects of the predator's effectiveness. Further research should include: collecting (with emphasis on the tropics and subtropics), describing and testing additional mite species against more pests; assaying pesticide effects; studying interactions between predators of different families, especially on uncultivated plants; and trying more predaceous mites against nematodes, plant diseases and weeds.