The effect of JA-mediated defenses on the survival and growth of western corn rootworm larvae, Diabrotica virgifera virgifera (Coleoptera:Chrysomelidae)

Plants protect themselves from insect herbivores using a variety of secondary metabolites, macromolecules and defensive structures. Nevertheless, many insect species apparently have adapted to the defenses they encounter in their food plants. It is unclear if coping with plant defenses imposes a significant cost on specialist herbivores.

Jasmonic acid (JA) is a key plant hormone responsible for regulating inducible defenses against chewing insects. Maize with double mutants of the OPR7 and OPR8 genes, which function in JA biosynthesis were used to manipulate the exposure of a specialist herbivore, the western corn rootworm (Diabrotica virgifera virgifera) to the plant’s defenses. We hypothesized that a cost of coping with plant defenses would lead to greater fitness of larvae feeding on mutant plants than on wild type plants.  Percent survival, head capsule and growth stage were compared between western corn rootworm larvae fed on detached roots of mutant and wild type maize.