Entomopathogenic fungi as a promising biological control agent against banana fruit scarring beetle, Basilepta subcostata (Jac.) (Chrysomelidae: Coleoptera)

Background Banana fruit scarring beetle (BFSB), Basilepta subcostata (Jac.) (Chrysomelidae:Coleoptera), is an important insect pest feeds on leaf and fingers, which affects the cosmetic value of the fruit. The pest is distributed in Assam, Bihar, West Bengal, Chhattisgarh, and North-eastern Hill regions of India. Results The pest is currently managed by foliar spray with insecticides. In order to identify eco-friendly control of the pest, attempts were made to isolate microbial agent and evaluate their potential to control the pest. A total of 27 entomopathogenic fugal isolates were obtained from Odoiporus longicollis (Oliver), Cosmopolites sordidus (Germar), Basilepta subcostata (Jac), and other insect Galleria mellonella (Fabr). Based on colony morphology, the collected fungal isolates were identified as Metarhizium spp. (17) and Beauveria spp. (10). Through ITS sequencing, the fungal isolates were further characterized at species level as B. bassiana (8), B. brongniartii (2), M. anisopliae (8), M. robertsii (6), M. guizhouense (2), and M. pinghaense (1). Their sequences were submitted in GenBank and obtained accession numbers. Among 27 isolates tested against B. subcostata under laboratory conditions, 3 isolates (M. anisopliae NRCBEPF-36, M. pinghaense NRCBEPF-7 and B. brongniartii NRCBEPF-27) recorded 100% beetle mortality, followed by 11 isolates with 95-99% and 13 isolates with 88-93% within 8 days of treatment. Conclusion This study highlights the two native North East India isolates B. brongniartii NRCBEPF-27 (MT151781) and M. anisopliae NRCBEPF-36 (MT140308) showed the significance to use as potential biocontrol agents against banana fruit scarring beetle B. subcostata. Further experiments under field conditions are required to evaluate their biological control efficacy against the pest.