The relationship between a geometric series of ten initial densities (Pi) of Rotylenchulus reniformis between 0 and 64 eggs, juveniles and young females/cm3 soil and growth of papaya (Carica papaya) "Paraguanera type" was investigated in one-liter clay pots. The Seinhorst model, y=m+(1-m)z[supP][supiû[supT], was fitted to plant average fresh and dry top weight. Tolerance limits (T) to the nematode for fresh and dry top weight of papaya plants were 0.25 and 0.18 eggs, juveniles and young females/cm3 soil, respectively. The minimum relative yields (m) were 0.67 and 0.65 at Pi = 16 eggs, juveniles and young females/cm3 soil for fresh and dry top weight of plants, respectively. The population of R. reniformis, determined 120 days after inoculation, fitted the model Pf=axy(1-q[supP][supi])(-[supe]logq)[sup-]1+(1-x)Pi+sx(1-y)Pi. Maximum nematode reproduction was 36-fold for the lowest initial population density (Pi), and the equilibrium density was 14 eggs, juveniles and young females/cm3 soil. The nematodes penetrated roots and stimulated the production of a number of specialized cells to form a distinct stelar syncytium.
