THE POTENTIAL FOR MANIPULATING CROP-PEST-NATURAL ENEMY INTERACTIONS FOR IMPROVED INSECT PEST-MANAGEMENT

This review identifies key ways in which manipulations of the crop env ironment based on detailed understanding of tritrophic interactions ca n contribute to improvements in the control of insect pests. Such appr oaches are likely to be of particular benefit against those pests, not ably certain species of Lepidoptera and aphid, which are difficult to control with insecticides because of insecticide resistance or suppres sion of natural enemies. Particular attention is given to the compatib ility (or otherwise) of partial plant resistance and biological contro l, citing examples which support contrasting tritrophic theories. Othe r areas considered and supported with examples include the use or effe cts of allelochemicals, refugia, intercropping, crop backgrounds, fert ilization regimes, parasitoid conditioning (by host plants) and transg enic crops. Examples of manipulations involving use of selective insec ticides which show compatibility with biological methods are also incl uded owing to their possible suitability in integrated crop management programmes.