Development of cost-effective entomopathogenic fungal biopesticides using cereal and pulse-based substrates for sustainable agricultural practices

The present study was conducted to assess the biological efficacy and economic viability of six agro-industrial substrates - rice, chickpea husk, maize, sorghum, wheat bran, and ragi - for the mass production of entomopathogenic fungi Metarhizium anisopliae, Beauveria bassiana, and Lecanicillium lecanii. All substrates were evaluated under standardized treatments, and spore yields (×10⁹ spores g-1) were quantified. Among the substrates, rice and chickpea husk (both treated with crushed + yeast extract) supported the highest sporulation, with B. bassiana reaching 3.47 and 3.25 spores g-1, M. anisopliae yielding 2.25 and 2.12 spores g-1, and L. lecanii producing 1.74 and 1.53 spores g-1, respectively. These values were significantly higher (CD: 0.466, 0.800, and 0.393, respectively) than those of lower-performing substrates such as ragi, which showed minimal sporulation across all fungi. Economic evaluation indicated that chickpea husk was the most profitable substrate, with a net income of ₹ 116.50 kg-1 and the highest benefit-cost (B:C) ratio of 4.70, followed by wheat bran and rice. In contrast, ragi incurred a slight loss (₹ -0.25 kg-1), with a B:C ratio of 1.00. Overall, chickpea husk emerged as the most promising substrate for large-scale production of entomopathogenic fungi, combining high spore output with superior economic returns, making it ideal for use in microbial biopesticide development.