This book presents an exhaustive overview of the theoretical foundations and practical applications of biocontrol in agriculture. It encompasses all kinds of nature-based approaches for crop protection: introduction and conservation of natural enemies, release of sterile insects, enhancement of plant defenses, use of microorganisms, biopesticides, and semiochemicals. Cutting-edge knowledge in population biology, microbial ecology, epidemiology and chemical ecology is presented in accessible terms. The potential of field application is discussed with regard to practical aspects but also socioeconomic constraints. The 62 authors are researchers from a large panel of disciplines, from theoretical biology to social sciences.