Abstract:In order to correctly predict the grub population dynamics for a timely control, we investigated and analyzed grub genesis regulation in first-cropping and continuous-cropping wheat fields by chessboarol sampling method using 1982~2002 data collected in the wheat lands of South Shanxi Province. Furthermore, the influence of weather factors on grub population dynamics for different cropping systems was investigated and regression equations established by the adoption of multi-analysis method. Four factors including grub original density (X1), August rainfall (X2), rainfall in the last 10 days of September (X3) and the 5 cm depth soil temperature in last 10 days of September (X4) were selected and their correlations with infection degree of grub genesis (Y) determined. Based on path-analysis, the most important factor is grub original density, followed by weather factors. Regression equation for the first-cropping wheat field is Y=0.037 9+0.596 9X1+0.001 9X2-0.009 8X3+0.046 0X4 and that for the continuous-cropping wheat field is Y=1.765 5+0.634 8X1-0.005 2X2-0.003 7X3-0.003 5X4. For 1982~2006, the prediction rate of the models are 88% and 92% respectively. The results show that the prediction model is highly suitable for forecasting grub population dynamics.
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