Population peaks modeling using Degree-Day of the cotton leafhopper Jacobiasca lybica (Hemiptera : Cicadellidae)

The cotton leafhopper Jacobiasca lybica is a serious pest of grapevines in Europe and recently in citrus fruits in Morocco. For an integrated pest management, the Degree Days (DD) model can be used for forecasting the pest development and plan the treatment accordingly, however, this model depends of many factors and does not always accurately predicts the pest occurrence. Our study aimed to build and compare a two development
models (based on DD and on raw time) adjusting the observed population peaks of J. lybica in real time during our past studies in Moulouya area of Morocco. Two candidate functions to fit our data (Bragg and Beta) were selected after the identification of the observed population peaks and determination of the optimal smoothing curve. The results demonstrated that the Bragg model with a variable slope peak and adjusted for individual height and width of peaks using ‘Degree Days’ predictor explained well our data compared to raw ‘ and the coefficients of determination for this optimized model with ‘ was higher than the ones of ‘Days model