Population prediction model for brown wheat mite (Petrobia latens) in rainfed wheat

Brown wheat mite, Petrobia latens (Müller) is a serious pest of rain-fed wheat particularly in the dry regions of north and central India. Forecasting system for the  pests in agro-ecosystem has become a major component in IPM. Considering this, pest weather relationship was established and prediction model was developed for implementing it in rainfed wheat system on regional basis in north Indian states. Based on the mite incidence and meterological data collected at Punjab Agricultural University, Ludhiana, from 2004 to 2013, pest incidence data was correlated with abiotic factors through multiple regression equation. It was observed that the mite population showed a positive correlation with maximum and minimum temperature and sunshine, whereas it showed a negative correlation with rainfall and relative humidity . It was observed that during the years 2006-07 and 2010-12, when there was moderate to heavy rainfall the population of mites was less while in the years, 2004-05, 2008-09, 2009-11, when there was comparatively very less rainfall and increase in temperature during February-March, the population of mites was also more. The coefficient of determination was calculated to measure the contribution of linear function of independent variables i.e. abiotic factors  on dependent variables i.e. mite counts. The multiple regression equation was calculated to be, Y = 94.0941 – 8.207X₁ + 3.617X₂ – 0.355X₃ – 0.553X₄ – 0.300X₅ + 21.277X₆ (R² = 0.2536). Based on this, it can be concluded that whenever there is winter drought i.e. there is very less rainfall and increase in the minimum temperature during December – February, the population of P. latensis expected to increase.

Key words : wheat, Petrobia latens, abiotic factors