Pesticide Research Journal

A field experiment was conducted at Agricultural Research Station (ARS), Dharwad during 2021-22 using Jadoo BG II cotton (Monsanto), with plots divided into protected and unprotected subplots. Insecticide sprays of NSKE 5% (5 mL L^-1), profenophos 50 EC (500 g ai ha^-1), spinetoram 11.7 SC (58.5 g ai ha^-1) and Lambda-cyhalothrin 5 EC (12.5 g ai ha^-1) were planned. The fourth spray was terminated as pests fell below economic threshold level (ETL). Results demonstrated a significant reduction in green boll damage from 8.8 to 42.0% in protected plots, compared to an increase from 42.5 to 76.3% in unprotected plots. Pink bollworm incidence per 25 bolls dropped from 4.3 to 15.0 larvae in protected plots, whereas it escalated to 29.1 larvae in unprotected ones. The percentage of good opened bolls was significantly higher in protected plots (86.9%) compared to unprotected plots (42.2%). Consequently, the seed cotton yield in protected plots reached 19.76 q ha^-1, substantially higher than the 13.01 q ha^-1 recorded in unprotected plots, resulting in a 30.4% avoidable yield loss. The economic analysis showed a benefit-cost ratio of 1.29 in protected plots, compared to unprotected plots (0.91). The findings highlight that while Bt cotton offers initial protection, supplementary insecticide applications are essential for maximizing yield and economic returns in areas with high pest pressure.