Protection of crop and ornamental plants from noxious organisms — insects, nematodes, mites, pathogens and weeds — is indispensable to modern agriculture. Despite intensive control efforts, about 50% of the world's crops are lost to these organisms, at an estimated annual cost of about 400 billion dollars. Ever since the advent of synthetic pesticides in the 1940s, modern crop protection has been largely based on chemical control. Pesticide expenditures are about 20% of total farming input costs, although this figure varies substantially according to crop and region. Mounting environmental concerns and pest control failures have made It increasingly clear that the use of toxic pesticides In agriculture should be drastically reduced all over the world.
