ABSTRACT
This chapter focuses on how weeds influence the overall levels of pest infestation, and whether, as suggested many times in the past, hedgerows are reservoirs for predators and parasites of insect pests of crops. Plants established during the inter-generation periods will tolerate considerable damage, when eventually infested, before yield is affected. As wild crucifers have co-evolved along with the insects, it seems more likely, that the present three-generation system has evolved in response to agricultural changes such as extending the season for cultivated crops and growing highly-nutritive cultivara that enable the pest to complete its life-cycle in a shorter period. Irrespective of which pest of cultivated horticultural field crops is being described, it is usual to see the same list of ground beetles mentioned for their general beneficial predatory qualities. The chapter concludes by reviewing some of the systems being proposed for alleviating pest problems in cruciferous crops.
