Comparative Efficacy Of Biopesticides And Synthetic Insecticides For Sustainable Management Of Wheat Aphid

Abstract

Wheat aphids reduce crop productivity through sap feeding, honeydew deposition and virus transmission. A field experiment was conducted at the Hazara Agriculture Research Station, Haripur, to compare synthetic insecticides and biopesticides against the wheat aphid complex. The trial was laid out in a randomized complete block design with three replications. Seven treatments were evaluated: imidacloprid 0.006%, methyl-o-demeton 0.025%, thiamethoxam 0.0075%, azadirachtin 0.001%, neem oil 2%, Beauveria bassiana and an untreated control. Aphid counts were recorded before application and at 24, 48, 72 and 168 hours after treatment. Natural enemy abundance, treatment persistence, yield and economic return were also assessed. Synthetic insecticides gave the strongest immediate aphid suppression, with imidacloprid and methyl-o-demeton producing 92.1% and 90.5% reduction at 72 hours, respectively. Thiamethoxam was also effective but caused greater reduction in natural enemy abundance than botanical treatments. Among biopesticides, azadirachtin gave moderate efficacy and maintained higher coccinellid and chrysopid abundance. Beauveria bassiana showed slower action but improved relative performance by 168 hours. Methyl-o-demeton produced the highest cost-benefit ratio, while imidacloprid provided the highest aphid reduction and yield response. Minimum temperature and morning relative humidity were positively associated with aphid abundance, while rainfall was negatively associated. The results suggest that synthetic insecticides remain useful for rapid knockdown under severe aphid pressure, but botanicals and microbial agents are better suited for predator-compatible IPM programs. A rotational strategy using economic thresholds, selective products and natural enemy conservation is recommended.

Keywords: Triticum aestivum; wheat aphid; Rhopalosiphum padi; Schizaphis graminum; azadirachtin; Beauveria bassiana; imidacloprid; IPM