Biocontrol of Major Lepidopteran Pests in Cabbage through Entomopathogenic Microbes under Manipur Valley Agro-Ecology

Abstract

Aim: The study aimed to evaluate the bio-efficacy of microbial insecticides against key lepidopteran pests of cabbage, namely the DBM (P. xylostella Linn.) and CB (P. brassicae Linn.), with a focus on developing eco-friendly alternatives to chemical pesticides. Study Design: A field experiment was conducted during the Rabi season of 2024 to 25 at the Vegetable Research Farm, College of Agriculture, Iroisemba, Central Agricultural University, Imphal. The cabbage variety Green Hero was used, and treatments were arranged in a Randomized Block Design (RBD) with three replications. Methodology: The experiment included microbial insecticides Beauveria bassiana at 5, 6, and 7 ml/L and Metarhizium anisopliae at 5, 6, and 7 ml/L along with Malathion 50 EC at 1 ml/L and  untreated control for comparison. Results: Malathion 50 EC @ 1 ml/L proved most effective, recording the highest reduction in pest population (64.21% in DBM and 59.30% in CB), maximum yield (20.0 t/ha), avoidable yield loss of 36.95%, and the highest benefit-cost ratio (15.2:1). Among microbial insecticides, M. anisopliae @ 7 ml/L and B. bassiana @ 7 ml/L also showed promising results, with reductions of 60.36% and 58.71% in DBM, and 58.60% and 56.24% in CB, respectively. These treatments also recorded appreciable B:C ratios of 4.8:1 and 5.4:1. Conclusion: While Malathion demonstrated superior efficacy and profitability, microbial insecticides exhibited significant potential as eco-friendly and sustainable pest management tools. Therefore, the integration of B. bassiana and M. anisopliae into Integrated Pest Management (IPM) strategies can contribute to sustainable cabbage cultivation.