Postdiapause development and prediction of emergence of female blueberry maggot (Diptera : Tephritidae)

Predictive models were developed to forecast the emergence of female bluebe rry maggot flies in highbush blueberries. Time to emergence at 20 degreesC for pupal samples transferred from outdoors late February through mid-March , in 1997 and 1998, was very similar, suggesting both diapause completion a nd minimal postdiapause development at this time. Linear and nonlinear mode ls were fitted to postdiapause development rates at several constant temper atures (7, 11, 15, 20, 25, and 30 degreesC). The low temperature developmen t threshold for the linear model was estimated at 4.7 degreesC, and the hea t accumulation required for median emergence was 934.3 degree-days. Rate su mmation was initiated on 1 March, over 3 yr, and model predictions were val idated with field emergence data. The linear model predicted emergence with an average error of <4 d of observed field emergence, for percentiles at a nd below the median, over a 3-yr period, compared with 4.0-5.4 d for the no nlinear biophysical model. The results of this study indicate that a simple linear model, driven by soil temperatures, can assist the monitoring of bl ueberry maggot fly in integrated pest management programs.