Stability of resistance to pod borer, Helicoverpa armigera in pigeonpea

Abstract

Because of increasing difficulties in controlling the damage by the pod borer, Helicoverpa armigera in pigeonpea with synthetic insecticides, it is important to identify genotypes with resistance to this pest for use in integrated pest management. Therefore, we evaluated a set of 12 diverse genotypes for resistance to H. armigera for two years over four plantings under natural infestation. There were significant differences among the genotypes in numbers of eggs and larvae, percentage pod damage, visual damage rating, and grain yield. The genotypes ICPL 187-1, ICP 7203-1, ICPL 98008, T 21, ICP 7035, and ICPL 332 exhibited moderate levels of resistance to H. armigera across planting dates, although there were a few exceptions. ICPL 187-1, ICP 7203-1, ICPL 84060, ICPL 87119, and ICPL 332 also showed better grain yield potential than the susceptible checks, ICPL 87 and ICPL 87091. All the genotypes were stable in their reaction to pod borer damage based on visual damage rating (except ICPL 87119 and ICPL 84060), but unstable for percent pod damage. Grain yield of most of the genotypes under H. armigera infestation was also unstable, except that of ICPL 87119, ICP 7035, and ICPL 332. Principal component analysis placed the test genotypes into different groups, and there is a possibility of increasing the levels and diversifying the basis of resistance to pod borer, H. armigera