Evaluation of Neem-Based Insecticides Against Resistant Strains of Helicoverpa armigera
DOI::
https://doi.org/10.70102/AEJ.2026.18.1.1کلمات کلیدی:
Helicoverpa armigera, Neem insecticides, Resistance management, Bioefficacy, Integrated pest management.چکیده
The increasing resistance of Helicoverpa armigera (Hubner) to synthetic pyrethroids necessitates the exploration of environmentally sustainable alternatives for effective pest management. This study evaluated the bioefficacy and ecological relevance of three neem-derived formulations azadirachtin 0.15% EC, neem oil 0.03% EC, and neem seed kernel extract (NSKE 5%) against cypermethrin-resistant and susceptible strains of H. armigera under laboratory and field conditions during 2022–2023. Leaf dip bioassays revealed a high resistance level to cypermethrin in the resistant strain (24.6-fold; LC₅₀ = 12.84 ppm) compared to the susceptible strain (LC₅₀ = 0.52 ppm). In contrast, neem-based formulations exhibited significantly lower resistance ratios, with azadirachtin (2.3-fold), neem oil (2.1-fold), and NSKE (2.5-fold), indicating minimal cross-resistance. Among the treatments, azadirachtin demonstrated the highest larvicidal activity, with LC₅₀ values of 5.21 ppm and 11.89 ppm against susceptible and resistant strains, respectively. Field evaluations in cotton agroecosystems showed that azadirachtin 0.15% EC at 2.0 L ha⁻¹ achieved superior pest suppression (68.3%) and reduced fruiting body damage (61.5%) compared to cypermethrin (42.7% and 38.9%). Additionally, oviposition deterrence assays indicated a significant reduction (74.6%) in egg laying on treated plants. The findings highlight the potential of neem-based insecticides as eco-friendly alternatives that not only effectively manage resistant pest populations but also reduce selection pressure and environmental risks associated with synthetic chemicals. Integration of such botanicals into resistance management programs can contribute to sustainable pest control and improved agroecosystem health.