Seasonal Incidence and Influence of Weather Factors on the Incidence of Spodoptera litura (Fab.) on Groundnut.

Investigations were carried out on the seasonal incidence of Spodoptera litura on groundnut at the Regional Research Station, Vriddhachalam, Tamil Nadu. Seven field experiments were conducted during Kharif 2001, Kharif 2002, Kharif 2003, Kharif 2004, Rabi 2001-02, Rabi 2002-03, and Rabi 2003-04 using groundnut variety VRI 2. The presence of Spodoptera was noticed two weeks after sowing and continued to exist up till harvesting of the crop. The peak incidence of pest occurs around 50-60 days after sowing. The correlation and regression studies showed that during Kharif season, the individual weather parameters have no significant correlation with the abundance of Spodoptera, but all weather parameters together can have influence up to 90% on the incidence of Spodoptera. During Rabi season also the effect of weather parameters individually on the abundance of Spodoptera was not significant. But, the R² value indicated that the influence of weather parameters on the incidence of Spodoptera was 98%. The forecasting model developed for Kharif season was Y = 12.309 + 2.37 X23, where, Y-Percent pest Incidence, X23 = Adjusted Minimum Temperature (2-week lag). The model developed for Rabi season was Y = 0.189 + 2.039 X12, where, Y-Percent pest Incidence, X12 = Adjusted Maximum Temperature (1-week lag). These models were validated with individual season data. [ABSTRACT FROM AUTHOR]