Dynamics of economic injury levels for cotton pink bollworm (Pectinophora gossypiella Saunders) in relation to control cost, cotton price and control efficacy

Abstract Background The evolution of Bacillus thuringiensis (Bt) resistance in cotton pink bollworm ( Pectinophora gossypiella ) has renewed reliance on insecticides, making precise application timing vital due to the pest’s internal feeding habit. This study refines the economic injury level (EIL) for pink bollworm using pest-infestation gradients and yield loss–damage functions. The EILs were estimated and converted to action thresholds (75% of EIL). The sensitivity to control costs, cotton prices, and control efficacy was considered in calculating the EIL. Additionally, the relationship between national pheromone-trap data (2015–2023) and green boll infestation was examined. Results Based on the average cotton prices, optimum control cost, and desirable control efficacy, EILs ranged from 7.1% to 8.6% of boll infestation, with corresponding action thresholds of 5.3% and 6.4% for < 120 days after sowing (DAS) and > 120 DAS crop stages, respectively. Control efficacy emerged as the most influential factor on EILs. Corresponding pheromone trap catch-based action thresholds were revised to 4.5 and 5.7 moths per trap per night, lower than the existing 8.0 moths per trap per night tied to a 10% boll infestation threshold. Validation using multi-location data supported refined estimates. Conclusions The study demonstrates that maintaining high control efficacy is central to keeping EILs low and enabling timely intervention against pink bollworm. Effective control reduces the pest’s damage potential, lowers the onset of economic loss, and supports earlier, more reliable ET-based actions. These results collectively ensure better suppression of pests and promote economically efficient, agronomically robust pest management. Graphical Abstract