Plasticity of yield components of winter wheat in response to cereal aphids

Phenotypic plasticity in plants is a naturally occurring phenomenon that plants have evolved to survive environmental change. In agriculture, environmental stress such as insect infestation can lead to reduction in yield components. Although insect resistance can be bred into crops, insect genetic variation can cause variability in resistance leading to yield reduction. However, the extent to which insect resistance is plastic may depend on crop genotype. A genotype × genotype matrix was designed to study the effect of within-species genetic variation on wheat × aphid interactions. We found that wheat yield components and aphid population growth were significantly influenced by both wheat genotype and aphid genotype. Furthermore, plasticity in wheat yield components depended on the wheat–aphid combination. The results indicate that wheat plasticity not only has a genetic basis, but that it is also influenced by the biotic environment. The consequences of plasticity in resistance to aphid genotypes found in our study in relation to crop breeding for insect resistance are discussed.