Bio-efficacy of Biopesticides against Fall Armyworm, Spodoptera frugiperda (J. E. Smith), in Rabi Maize

Fall armyworm, Spodoptera frugiperda (J. E. Smith), causes substantial leaf damage in maize, but comparative field evidence on biopesticide performance during the Rabi season remains limited. A field experiment was conducted during the Rabi season of 2025–26 at Krishi Vigyan Kendra, Dhule, Mahatma Phule Krishi Vidyapeeth, Rahuri (Maharashtra), to evaluate the bio-efficacy of biopesticides against fall armyworm, Spodoptera frugiperda (J. E. Smith), in maize (Zea mays L., hybrid Harlal 7272). The experiment, laid out in a randomised block design with seven treatments and three replications, comprised Super Biomix @ 10 ml/L, Lecanicillium lecanii 1.15% WP @ 5 g/L, Beauveria bassiana 1.15% WP @ 5 g/L, Metarhizium anisopliae 1.15% WP @ 5 g/L, Metarhizium rileyi 1.15% WP @ 5 g/L, Azadirachtin (10,000 ppm) @ 2 ml/L and an untreated control, and two sprays were applied at a 15-day interval. On the basis of the cumulative mean across both sprays, Metarhizium rileyi 1.15% WP @ 5 g/L was the most effective treatment, recording the lowest Davis scale leaf damage rating (2.46), the lowest per cent leaf damage (19.47%) and the lowest larval population (0.86 larvae/plant), and was statistically at par with Metarhizium anisopliae 1.15% WP @ 5 g/L (2.49, 20.30% and 0.94 larvae/plant, respectively), as against 4.08, 37.57% and 1.77 larvae/plant recorded in the untreated control. Five of the six biopesticide treatments significantly increased grain yield compared with the control, with M. rileyi recording the highest yield (55.80 q/ha), the highest net monetary return (Rs. 35,375/ha) and the highest incremental cost-benefit ratio (1:7.1), followed by M. anisopliae (54.35 q/ha; ICBR 1:6.4). The results suggest that entomopathogenic fungal biopesticides, particularly M. rileyi and M. anisopliae, can be recommended as effective, economical and eco-friendly alternatives to synthetic insecticides for the management of fall armyworm in Rabi maize.