Developmental plasticity of two ecological races of the fall armyworm, Spodoptera frugiperda, feeding on natural host plants

The life histories of two ecological races/strains (corn and rice) of the Fall armyworm Spodoptera frugiperda were studied under laboratory conditions. The individuals descended from 30 different maternal lines and were subjected to two different diets (corn plants and Florona grass). We found significant differences in the body sizes of the final adults. On average, adults from the corn strain were larger than the adults from the rice strain. Corn strain larvae feeding on Florona grass develop faster, grow larger, but suffer from high mortality rates. When feeding on corn plants on the other hand, the adults of the two strains reach a similar average size and exhibit low mortality rates. However, their growth trajectories were extremely plastic which is ecologically and evolutionarily important for an organism’s success.