Interaction of acid exudates in chickpea with biological activity of B acillus thuringiensis towards H elicoverpa armigera

The gram pod borer, H elicoverpa armigera, is one of the most important constraints to chickpea production. High acidity of chickpea exudates is associated with resistance to pod borer, H . armigera ; however, acidic exudates in chickpea might influence the biological activity of the bacterium, B acillus thuringiensis ( B t ), applied as a foliar spray or deployed in transgenic plants for controlling H . armigera . Therefore, studies were undertaken to evaluate the biological activity of B t towards H . armigera on chickpea genotypes with different amounts of organic acids. Significantly lower leaf feeding, larval survival and larval weights were observed on ICC 506 EB , followed by C 235, and ICCV 10 across B t concentrations. Leaf feeding by the larvae and larval survival and weights decreased with an increase in B t concentration. However, rate of decrease in leaf feeding and larval survival and weights with an increase in B t concentration was greater on L 550 and ICCV 10 than on the resistant check, ICC 506 EB , suggesting that factors in the resistant genotypes, particularly the acid exudates, resulted in lower levels of biological activity of B t possibly because of antifeedant effects of the acid exudates. Antifeedant effects of acid exudates reduced food consumption and hence might reduce the efficacy of B t sprays on insect‐resistant chickpea genotypes or B t ‐transgenic chickpeas, although the combined effect of plant resistance based on organic acids, and B t had a greater effect on survival and development of H . armigera than B t alone.