Abstract
The study was designed to investigate the impact of water stress on varietal response to cotton cultivars, Helicoverpa armigera and its associated entomophagous insects [Chrysoperla carnea (Stephens) and Habrobracon hebetor (Say)] as well as the feasibility of different Integrated Pest Management (IPM) modules for management of H. armigera. For this purpose, five drought resistant cotton genotypes i.e., FH-941, FH-187, FH-4243, FH-1000 and FH-207 were sown under irrigated and drought conditions. Larval population of H. armigera was low on water stressed plants (0.32 larvae/plant) as compared to irrigated plants (0.45 larvae/plant). In contrast, H. armigea caused more damage to stressed plants (16.90%) than irrigated plants (14.58%). FH-4243 was evaluated as resistant genotypes on the basis of less percent damage by H. armigera for both irrigated and drought conditions with value of 13.24 and 09.59%, respectively. Population of C. carnea was statistically similar under both for irrigated (0.20 larvae/plant) and drought conditions (0.19 larvae/plant). Unlikely, low parasitism of H. armigera by H. hebetor was observed under drought (14.64%) than irrigated condition (20.79%). Treatment involving integration of Neemosal, C. carnea and H. hebetor demonstrated 0.09 larvae/plant and provided maximum control of H. armigera; whereas alone application of Neemosal proved least effective against H. armigera (0.32 larvae/plant). On the basis of cost benefit ratio (CBR), module-15 involving integrated implementation of Spinosad, Neemosal, C. carnea and H. hebetor explained highest yield (1639.52 kg/ha) and CBR (1: 6.15) and proved economical and effective IPM module. In conclusion, water stress condition had positive impact on H. armigera feeding-damage (bi-trophic interaction) but had negative impact on parasitism. Integration of bio-control agents, botanicals and reduced-risk insecticides would be more cost-effective than their alone or two-level integration. (C) 2015 Friends Science Publishers