A SIMULATION-MODEL FOR PREDICTING THE EFF ICIENCY OF BIOLOGICAL-CONTROL OF SPIDER MITES BY PHYTOSEIID PREDATORS .2. VALIDITY TESTS AND DATANECESSARY FOR PRACTICAL USAGE

Validity tests of the simulation model developed in the previous repor t (SAITO et al., 1996) using two sets of experiments under two differe nt greenhouse conditions revealed that the model was able to precisely predict the dynamics of predator-prey interactions with minor changes in a Few variables: On strawberry plants in a well regulated glasshou se, when the predator searching efficiency was decreased to 87% of the standard value and the ratio of prey female and predator Female at wh ich the predators begin to disperse was ca. 7: 1, the dynamics of pred ator-prey populations were well simulated. On cucumber plants in a vin yl-house under free-ranging temperature conditions, 30% decrease in se arching efficiency and 20% decrease in sedentary rate were necessary t o simulate the most fitting pattern of predator-prey dynamics. These c hanges in rate variables were thought to be reasonable considering the differences in features and sizes of the plants. Therefore, the prese nt model appears to be useful in demonstrating the controlling process and predicting the result of biological control. Several environmenta l and biological factors which should be determined before biological control is implemented were also discussed.