Since the neolithic revolution, humans have, in making plants more attractive to ourselves via more sugar and starch, also give pests more reason to consume them. With each human innovation to keep the food for ourselves, the pests evolve to evade it--new formulation of pesticides, genetic modification of the plants, all of which is expensive (and available to bigger rather than smaller farmers) and short-lasting. Dyer offers a good introduction to evolution and genetics and their bearing on agricultural food production, and examines the pre-modern methods (avoiding monoculture, crop rotation, using other predators like spiders to control crop-eating bugs) as possibilities.