With the proliferation of patents and the marketing blitz by these companies, we'll have only a handful of varieties that are sterile. There will be no new varieties coming out of natural cross pollination because we are left with sterile patented varieties.
Ecosystems are not static, they are extremely dynamic and never balanced.
Exactly. The viruses, bacteria and pests are evolving naturally; they are increasing their resistance to the existing pesticides. With the sterile varieties, there is no evolution, no adaptation to the changing environmental conditions and the changing pests.