Each compartment was constructed to contain a certain number of boxcars. The status of a boxcar was defined with state variable arrays, number of aphids in each boxcar, mortality, age and its standard error, average temperature that the aphids experienced. The number of aphids in each boxcar was calculated from development, reproduction, surviving, morph determination and migration. Those processes are affected by the daily average and maximum temperatures, plant growth stage, and syrphid density. The simulation model was written to a simulation program with Visual Basic.
High temperature is an important factor in the aphid population control.
Survival rates, longevity and fecundity were significantly reduced by temperature, exposure time and developmental stage of aphids. A combined logistic model was developed to describe survival rate, longevity and fecundity at different high temperature conditions. The mature stage of the aphid more seriously suffers from the high temperature than the young stage dose. The survival rate and life fecundity was reduced as the exposure days increased, but longevity was slightly affected by exposure time. There is an apparent tendency that the survival rate, longevity and life fecundity decreases as temperature increases.