Nematicidal activity of endophytic bacteria Bacillus spp. against Meloidogyne javanica: effects on juvenile mortality, reproduction factor, and growth of soybean plants

Abstract

Abstract This study evaluated four endophytic bacteria Bacillus strains as biocontrol agents against Meloidogyne javanica. All produced hydrolytic enzymes (amylase, cellulase, protease, chitinase) and showed strong nematicidal activity, with juvenile mortality comparable to the commercial nematicide Avicta (100%). Egg hatching was significantly inhibited, reducing juvenile emergence. In greenhouse trials, bacterial treatments reduced the total nematode population, defined as the aggregate of all developmental stages recovered from plant roots, by more than 65% compared with the control, leading to a substantially lower reproduction factor (RF < 15 versus 40 in the control). Plant growth varied by strain: shoot fresh weight was the highest with B. thuringiensis SB003 (43.1 g) and B. velezensis SB004 (39.5 g); shoot dry biomass increased with B. amyloliquefaciens B002 (8.32 g) and SB004 (8.82 g). Root biomass was the greatest with B001 (38.3 g), SB003 (37.9 g), and SB004 (34.2 g), surpassing the control (30.8 g) and chemical nematicide (24.7 g). Endophytic Bacillus spp. thus offered effective, sustainable nematode control while enhancing plant growth.