Zinc as an Important Factor Determining Resistance against Helicoverpa armigera Herbivory in Pigeon Pea ( Cajanus cajan L.)

The potential of enzyme inhibitors against infestation of insects serves as attractive strategy for the management of devastating pests. In an effort to identify some effective and eco-friendly inhibitors of a damaging pest, Helicoverpa armigera, iron and zinc were found to be potent inhibitors of H. armigera α-amylase, which is an important digestive enzyme required for its survival. This observation motivated us to determine the status of iron and zinc in different pigeon pea genotypes in response to H. armigera herbivory. In general, there was significant decline in zinc content in developing seeds and pod wall after herbivory. However, zinc content was significantly higher in moderately resistant genotypes than moderately susceptible genotypes in infested developing seeds. Significant accumulation of iron was also observed in developing seeds of moderately resistant and intermediate genotypes after the pod borer attack. Higher content of zinc in pod wall of moderately resistant genotypes could determine their resistibility status against H. armigera herbivory.