Bio-efficacy and economics of biopesticides against tobacco cutworm, Spodoptera litura Fab. on menthol mint

Abstract

A field experiment was conducted to study the bio-efficacy and economics of biopesticides against tobacco cutworm, Spodoptera litura Fab. on menthol mint during the kharif season of 2023 at Dr. Rajendra Prasad Central Agricultural University, Pusa (Samastipur), Bihar. Among the treatments, Bacillus thuringiensis var. kurstaki applied @ 1 l/ha was found to be the most effective, reducing the mean larval population by 42.92 per cent. The next most effective treatment was Beauveria bassiana @2.5 kg/ha (38.08%) which was statistically comparable to Metarhizium anisopliae @1.5 l/ha (34.91%) and Azadirachtin (1500 ppm) at 0.75 l/ha (32.13%). The least effective treatments were Neem oil (2%) applied at 10 l/ha (28.02%) and NSKE (5%) at 25 kg/ha (24.76%), although both were more effective than the untreated control plot. The highest B:C ratio was observed for Bacillus thuringiensis var. kurstaki at 1 l/ha (1:1.52) followed by Beauveria bassiana at 2.5 kg/ha (1:1.32), Metarhizium anisopliae at 1.5 l/ha (1:1.29) and Azadirachtin (1500 ppm) at 0.75 l/ha (1:1.26). NSKE (5%) at 25 kg/ha and Neem oil (2%) at 10 l/ha yielded benefit-cost ratios of 1:0.76 and 1:0.70 respectively, while the untreated control plot had the lowest ratio of 1:0.61.