Herbivorous insects—a threat for crop production

Abstract

It is estimated that, in spite of plant breeding and pest control efforts, 15% of crop yield is worldwide lost to herbivory by insects. Examples demonstrate how insect pests have developed in the past and why they will develop in the future. The evolutionary potential of insects to become new pests is considered for traditionally and genetically modified crop varieties. The immune system of plants is presented step by step. Generalist herbivores can be effectively repelled, but specialist herbivores are much harder to repel. They use plant defenses as cues for host plant recognition. Next to direct defense, indirect defense by attracting natural enemies of (specialist) herbivores is explained. Finally, the interactions of plants and insect herbivores with microbial symbionts—and their consequences—are discussed.