Crop protection: why and how

The answer to the question 'why' has proximate and ultimate roots. The proximate answer, 'pests take our harvest', compels one to act. Crops and their pests are products of domestication, the ancestors of the pests still exist in nature. Eradication is impossible and undesirable. What action should be taken? The ultimate answer, how organisms became pests, may tell us how to act. Old cropping systems had man-made ecological sustainability but do not have economic sustainability in modern times. To achieve both we must prevent rather than control pest outbreaks, using old and new ecological tricks, with application of pesticides in emergency cases only. The action will require a move from chemistry to ecology. Optimism on regaining some ecological sustainability is mixed with doubts on economic sustainability. Can farmers be asked to invest in the future at the expense of today's family income? Crop protection faces new technical and moral problems.