Population Dynamics of a Nematophagous Fungus Lecanicillium muscarium, and Root Knot Nematode, Meloidogyne incognita to Assess the Disease Pressure and its Management

A series of experiments were conducted in a greenhouse to determine the population dynamics of the root knot nematode, Meloidogyne incognita, and the nematophagous fungus, Lecanicillium muscarium, on tomato. The nematode population densities were measured by determining the number of galls and egg masses, juveniles and eggs per root system, and reproduction factor. Four initial populations (Pi) (500,1000,1500, and 2000 eggs) mixed with antagonistic fungal conidia levels (1.10(3),1.10(4), 1x10(5), 1x10(6)) were used during the experiments. The roots were stained with Phloxine B, the egg-masses were quantified, the root systems were rated for galling, and the egg masses were measured on a 0 to 5 scale, where 0 = no gall or egg masses, 1 = 1-2,2 = 3-10,3 =11-30, 4 = 31-100, and 5 = >100 galls or egg masses per root system. The nematode reproduction rate (Pf/Pi, where Pf = final nematode population/initial nematode population) decreased proportionately with the increased initial fungal conidial Pi. Foliage growth was directly related to fungal Pi and inversely to nematode Pi. Our results showed that the higher Pi of L muscarium was associated with the lower Pf of M incognita. Foliage growth increased with increased fungus inoculum.