Emergence model for field populations of overwintering Heliothis zea and H. virescens (Lepidoptera: Noctuidae)

The rate of emergence of a field population of overwintering corn earworm, Heliothis zea (Boddie), and tobacco budworm, Heliothis virescens (F.), was observed in the College Station, Tex., area. The population was manipulated into a state of diapause in the laboratory before being placed in individual artificial pupal chambers in a plot of bare soil. The temperature of the chambers was monitored hourly, and the chambers were inspected daily to determine whether emergence had occurred. A computer model was developed to simulate pupal developmental response during diapause and pupation based on hourly temperature over time. The predicted time of emergence using the model compared favorably with observed values from the field and the laboratory.