Temperature-dependent Model for Sorghum Midge (Diptera: Cecidomyiidae) Spring Emergence

A temperature-dependent, two-component model, based on constant-temperature development data, was formulated which described the emergence of overwintered sorghum midges, Contarinia sorghicola (Coquillett) in the field. The first model component used a poikilotherm rate equation to predict emergence rates as a function of temperature. The second component distributed emerging adults over normalized time using a temperature-independent cumulative Weibull distribution. When coupled, components formed a temperature-dependent simulation model which described the spring emergence of overwintered midges from 1979 to 1982. The model tended to predict emergence before it actually occurred in the field. This discrepancy was corrected by incorporating a 1.27-cm precipitation delay factor which modified predicted rates to reflect the retarding effects of rainfall on daily emergence. Once precipitation delay was incorporated, the model very accurately predicted adult emergence during all 4 years.