9628977 Berenbaum Although the presence of toxins in plants has long been associated with resistance to insects, the idea that low nutrient quality can similarly protect plants against their insect enemies has remained untested for over forty years. The goal of this project is to measure variation in the nutritional quality of Pastinaca sativa, the wild parsnip, and determine whether the low levels of such vital insect nutrients as protein, fatty acids, vitamins, and sugars are associated with escape from attack by Depressaria pastinacella, the principal insect enemy of the plant. This project is of interest not only because it can contribute to the conceptual understanding of plant-insect interactions, which collectively constitute the principal form of biological interaction on the planet, but also because it can potentially lead to new and environmentally compatible approaches to pest control. Breeding strains of crop plants that are resistant to insect damage based on their low content of essential insect nutrients can lead to pest control without use of synthetic organic insecticides. Nutrients that are essential requirements for insects but are relatively important in human diets can be specifically targeted for manipulation. Many plant pests feed on only a narrow range of crop species; because of their extremely specialized diet, plant-feeding insect pests are particularly vulnerable to nutritional deficiencies in their diet in that missing nutrients in many cases cannot be compensated for by switching to other plant species. Adoption of such a control strategy can lead to improved yields, reduced risks of resistance acquisition, and reduced impacts on nontarget species compared with conventional pesticide treatments.