The predatory nematode, Mononchoides fortidens (Nematoda: Diplogasterida), suppresses the root-knot nematode, Meloidogyne arenaria, in potted field soil

Experiments were conducted to evaluate the effect of inoculum density and application time of the predatory nematode, Mononchoides fortidens, against the root-knot nematode, Meloidogyne arenaria, on tomato plants (Lycopersicon esculentum) cv. Pusa Ruby grown in pots containing 500 g field soil infested with 10 s stage juveniles (J2)/g soil. Addition of M. fortidens to pots at different concentrations (0, 50, 100, 150, 200, and 250 per pot) 7 days prior to tomato planting reduced root galling and the final population of M. arenaria and increased vegetative growth of tomato plants and root-mass production, compared with zero predators. The beneficial effect of adding predatory nematodes to infested potted field soil increased exponentially with concentration up to 200 nematodes per pot. Application of predatory nematodes 2 days after tomato planting was ineffective. Efficacy of predatory nematodes applied at the time of planting was intermediate between the treatments where predatory nematodes were added before and after tomato planting. At the end of the experiments, higher numbers of predators were recovered than were inoculated.