Abstract

The present study aimed to evaluate the field efficacy of four promising isolates (Bb-5a, Bb-23, Bb-45, and Ma-35) of entomopathogenic fungi (EPF) against maize stem borer, Chilo partellus, during winter seasons over a two-year period at ICAR-National Bureau of Agricultural Insect Resources (NBAIR), Bengaluru, Karnataka, India. All tested EPF isolates demonstrated superior efficacy compared to the control in suppressing maize stem borer damage across both seasons. Pooled data analysis revealed that the incidences of dead hearts (DH), stem tunnelling (ST), galleries (per plant), and exit holes (per plant) ranged from 8.7-18.3%, 5.06-7.97 cm/plant, 1.69-2.42 per plant, and 2.72-5.12 per plant, respectively, compared to untreated control values of 21.6%, 8.93 cm/plant, 3.23 per plant, and 6.72 per plant, respectively. Among all treatments, Bb-5a exhibited significantly superior efficacy in reducing the incidence of dead hearts (8.7%), stem tunnelling (5.06 cm/plant), galleries (1.69 per plant), and exit holes (2.72 per plant). Furthermore, Bb-5a demonstrated a higher yield of 68.8 t/ha, representing a 17.65% increase over the control. Bb-5a isolate also recorded higher gross returns of ₹ 82660/ha, resulting in a maximum net profit of ₹ 56660/ha with a cost-benefit ratio of 1:3.18. These findings highlight the potential of Bb-5a as an effective biocontrol agent against maize stem borer, offering economic benefits to farmers.

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