Field evaluation of the entomopathogenic fungi enriched with organic amendments against Holotrichia consanguinea Blanchard (Coleoptera: Scarabaeidae) infesting groundnut crop

Abstract Background White grubs are highly polyphagous and most destructive soil pests inflicting damage to a groundnut crop that causes economic yield losses in commercial groundnut production in India. In this study, potential of the two entomopathogenic fungi (EPF) viz., Metarhizium anisopliae (Metchnikoff) Sorokin and Beauveria bassiana (Balsamo) Vuillemin enriched with organic amendments like neem cake, castor cake, vermicompost and poultry manure was evaluated to manage buildup of white grub population in groundnut crop. Results Results showed that the plot treated with soil application of vermicompost @ 1 ton/ha + M. anisopliae 1.15 WP (1 × 108 cfu/g) @ 2 kg/ha showed the least amount of plant mortality due to white grub which was at par with castor cake @ 1 ton/ha + M. anisopliae 1.15 WP (1 × 108 cfu/g) @ 2 kg/ha and neem cake @ 1 ton/ha + M. anisopliae 1.15 WP (1 × 108 cfu/g) @ 2 kg/ha which showed only 1.74, 2.00 and 2.24% plant damage, respectively. Plots treated with vermicompost @ 1 ton/ha + M. anisopliae 1.15 WP (1 × 108 cfu/g) @ 2 kg/ha had the fewest (0.19) white grubs per one meter row length. Based on highest pod yield, net realization and net gain, the treatment with soil application of vermicompost @ 1 ton/ha + M. anisopliae 1.15 WP (1 × 108 cfu/g) @ 2 kg/ha was found most effective treatments for the management of white grub in groundnut. Conclusions Results indicated that M. anisopliae supplemented with various organic amendments, such as vermicompost, castor cake, and neem cake can be commercialized as a healthy alternative to minimize the use of synthetic pesticides in groundnut crops for white grub management.