Abstract
Optimum timing of insecticide application for the white peach scale, Pseudaulacaspis pentagona (Targioni), that had infested tea trees was estimated using a simulation method. Fenpyroximate-buprofezin mixture was used as the test insecticide. Mortalities of the larvae (age, 1 to 8 days) of the scale were investigated, after using the insecticide, in a laboratory. In addition, residual activities of the insecticide that lasted up to 4 days after the spraying on the hatched larvae of the scale were investigated in a field and the laboratory. On the basis of these experimental data, and assuming that hatchability is represented as a sigmoid curve, the effects of the timing of the insecticide application on larval mortality in tea fields were simulated. The simulation results showed that larval mortality was the highest at a hatchability of 73.1% and that the optimum application period of the insecticide was 3 days.
