The best alternative to chemical control is often seen as being biological control - the introduction of natural enemies in areas where foreign pests become abundant. However biological control alone is not always sufficient to maintain pest populations under a tolerable level; and it is necessary to learn how to make it compatible with other methods of control and in particular with chemicals in integrated control programs. Data on these important aspects was collected and elaborated over a period of seven to eight years and synthesized in this volume which was originally published in 1976. The data relates to five groups of species recognized as main agricultural pests over vast areas of developing countries. It shows how complex the interrelationships between microorganisms are how much research effort has to be invested in such disciplines as systematics physiology ethnology and ecology for their understanding. Language: English