Efficacy of combination insecticides against pod fly on pigeonpea

Pod fly (M. obtusa) in pigeonpea is difficult to manage due to its internal larval feeding habit which significantly reduces the effectiveness of conventional insecticides. Continuous use of single-molecule insecticides has caused resistance, pest resurgence and environmental risks. Early detection is challenging as visible symptoms appear late and limited farmer awareness about the efficacy and cost–benefit of combination insecticides restricts their field adoption. A field investigation was conducted during 2024–2025 at the Entomology Section, College of Agriculture, Nagpur, to evaluate the efficacy and cost-effectiveness of combination insecticides against pod fly (Melanagromyza obtusa) on pigeonpea. Nine treatments, including an untreated control were tested. Chlorantraniliprole 9.3% + Lambda-cyhalothrin 4.6% ZC @ 200 ml/500 L proved most effective in reducing pod damage and grain loss caused by M. obtusa. This was followed by Thiamethoxam 12.6% + Lambda-cyhalothrin 9.5% ZC and Novaluron 5.25% + Indoxacarb 4.5% SC which also significantly suppressed infestation. All the combination insecticide treatments were statistically superior to the untreated control in minimizing pod fly damage. The highest grain yield (14.03 q/ha) was recorded in the Chlorantraniliprole + Lambda-cyhalothrin treatment contributing to better crop performance. However, Thiamethoxam + Lambda-cyhalothrin emerged as the most economical option recording the highest ICBR of 1:9.09 with a net return of Rs. 47,751/ha. These results highlight the potential of selective combination insecticides in achieving both effective pest suppression and higher economic returns in pigeonpea cultivation under field conditions. The study aims to identify insecticide combinations that provide broad-spectrum control, longer residual activity and superior cost–benefit ratios compared to conventional single-molecule treatments. Through field evaluation and integration of efficacy with Incremental Cost-Benefit Ratio (ICBR) analysis the research offers a balanced assessment of both biological effectiveness and economic sustainability. The findings are expected to guide the development of eco-efficient and practical pest management strategies for pigeonpea cultivation.