Species diversity of animals and plants is relevant to pest management in very different ways. Plant diversity provides sources of biologically active natural products and of genes for plant resistance. Animal diversity is involved in both harmful and beneficial interactions between crops and weeds or uncultivated land and in provision of potential biological control agents. The pest management implications of changes in biological diversity therefore need to be considered at a smaller scale in the management of cropping systems and on a larger scale in development programmes and national land use planning.
