Metarhizium anisopliae reduces Meloidogyne incognita reproduction and promotes tomato plant growth

Abstract

Root-knot nematodes, especially Meloidogyne incognita, cause substantial yield losses in tomato production and remain one of the most challenging soilborne pathogens in Brazil. The entomopathogenic fungus Metarhizium anisopliae has been recognized for both its nematicidal activity and its capacity to promote plant growth, although these two functions have rarely been demonstrated simultaneously in the same study. This work evaluated the effectiveness of M. anisopliae in stimulating tomato growth and reducing M. incognita reproduction under in vitro and greenhouse conditions. Three experiments were conducted using tomato hybrid ‘Sophia’, with treatments including fungal application, nematode inoculation, and their combination. In both experiments, M. anisopliae significantly increased plant height, shoot fresh mass, and root fresh mass compared with untreated controls. The effect of M. anisopliae was also directly evaluated on egg masses under in vitro conditions to verify the hatching rate of juveniles. When applied to nematode-infested plants, the fungus reduced nematode reproduction by 56% in Experiment 1 (FR: 4.2 to 1.8) and by 55% in Experiment 2 (FR: 5.2 to 2.3).Single and double applications of M. anisopliae produced similar agronomic responses, indicating that one application was sufficient for growth promotion. Overall, the results demonstrate that M. anisopliae acts as both a plant growth promoter and an effective biological control agent against M. incognita, bringing greater prominence to the management of plant-parasitic nematodes, particularly root-knot nematodes in tomato.