MODELING THE POPULATION-DYNAMICS OF THE SUGAR-BEET CYST-NEMATODE HETERODERA-SCHACHTII

A differential equation is used to simulate the population dynamics of the sugar beet cyst nematode Heterodera schachtii in rotations compri sing host and non-host crops. Transition probabilities between develop mental stages are formulated as density dependent. The number of gener ations within one year is determined by the prevailing environmental c onditions. The parameter set is calibrated to standard cropping system s. Although the structure of the model is kept simple, the model outpu t compares well with different sets of experimental field data. The mo del can be used to forecast realistic long-term changes of nematode de nsity in sugar beet rotations.