Integration of Heterorhabditis indica with other Biorationals for Managing Chickpea Pod Borer, Helicoverpa armigera (Hub.)

Abstract

A successful management strategy was developed against chickpea pod borer, Helecoverpa armigera (Hub) by integrating locally isolated entomopathogenic nematode, Heterorhabditis indica (RCR) with other entomopathogens like Helicoverpa armigera nuclear polyhedrosis virus (HaNPV) and Bacillus thuringiensis (Bt) and botanicals. Preliminary laboratory studies were conducted, to standardize the optimum dosage of nematodes required for field application, to evaluate the compatibility of nematode with entomopathogens and botanicals and their combinations. The optimum dosage of infective juveniles was standardized to third (LC₅₀ of 145 IJs/larva) and fourth (LC₅₀ of 195 IJs/larva) instars based on the concentration mortality response. Persistence study on chickpea foliage in field condition indicated that, infective juveniles along with 0.1 % glycerol survived better (80%) compared to other anti-dcssicants. In compatibility studies, though H. indica was compatible with other entomopathogens, but was susceptible to higher concentrations of aqueous leaf extracts of some selective botanicals. A series of laboratory bioassay was carried out to select best combinations of H. indica with other entomopathogens and botanicals against third and fourth instar H. armigera and these were tested in field for two consecutive years. Two year field evaluation indicated that, sequential application of H. indica + Prosopis juliflora (1 lakh IJs/I + 10%) at 50 and 75 days after sowing was superior with highest larval reduction (23.47%), minimum pod damage (11.27%) and maximum seed yield (19.24 q/h).