Biological control potential and modes of action of Bacillus megaterium against Meloidogyne graminicola on rice

This paper describes the development of a biological control system for Meloidogyne graminicola using rice root inoculations of the bacterium, Bacillus megaterium, which was isolated from a rice-growing region of Taiwan. Treatment with B. megaterium resulted in a greater than 40% reduction in nematode penetration and gall formation compared with non-treated rice roots, and, in a separate study, colonization of rice roots with B. megaterium decreased migration of M. graminicola to the root zone by nearly 60% compared with that of non-treated roots. Exposure of M. graminicola eggs to secondary metabolites of B. megaterium reduced hatching by over 60% compared with eggs not exposed to the bacteria. This paper will present modes of action through which B. megaterium reduces M. graminicola damage, and it will discuss challenges in developing nematode biological control systems for rice cultivation in intermittently anoxic and oxic soil environments.