Today, at the beginning of the third millenium, just three cereal grains - wheat, rice and maize - dominate the world's food supply, accounting for some 75 % of all grains produced. This food "oligoculture" poses some risks for the future of humankind. The risk of catastrophic food crop failure through insect pests or fungal diseases is ever greater as genetic diversity is reduced. The introduction of genetically modified cereals may exacerbate this situation, as different speeies will share the same genes conferring resistance to pests. The intensive cultivation practices needed to produce...