Endophytic colonization of white jute (Corchorus capsularis) plants by different Beauveria bassiana strains for managing stem weevil (Apion corchori)

Beauveria bassiana (Balsamo) Vuillemin (Ascomycota: Hypocreales), an entomopathogenic fungus, was introduced through seed inoculation with spore suspension as an endophyte in white jute (Corchorus capsularis L.), a bast fiber crop. Out of nine B. bassiana strains, seven, viz., ITCC 6063, ITCC 4512, ITCC 4563, ITCC 5562, ITCC 4796, ITCC 5408 and ITCC 4705, became established as endophytes. The endophytic colonization was initially detected by cultivation on selective medium. Colonization was confirmed by polymerase chain reaction (PCR) using sequence characterized amplified region (SCAR) marker. Endophytic B. bassiana strains colonized in leaves of all the plants grown from treated seeds. However, the colonization frequency varied among the strains. The highest colonization frequency (70.09%) was recorded in ITCC 6063 followed by ITCC 5562 (67.67%) and ITCC 5408 (64.17%); ITCC 4512 exhibited the lowest (42.54%) colonization. ITCC 4925 and ITCC 4644 did not show any colonization. Endophytic colonization of B. bassiana reduced stem weevil infestation under pot culture. ITCC 5408 and ITCC 6063 were found most efficient, with only 10.44% and 14.06% infested plants, respectively.