Influence of prevailing weather parameters on population dynamics of fruit borer, Helicoverpa armigera (Hubner) on tomato in Haryana

A field experiment was conducted for two years (2016-17 and 2017-18) at Entomological Research Area, Department of Entomology, CCS Haryana Agricultural University, Hisar to ascertain the influence of various meteorological parameters on population fluctuations of Helicoverpa armigera on tomato. The maximum oviposition (4.60 eggs/plant) was recorded during 15th standard meteorological week (SMW) whereas larval population was at peak (4.91 larvae/plant) during 16th SMW. The larval population showed significant positive correlation with maximum temperature (r=0.617*) and highly significant negative correlation with morning (r=-0.784**) as well as evening relative humidity (r=-0.814**). Maximum eggs parasitization (12.85 %) by Trichogramma sp. was recorded during 16th SMW. These trichogrammatid parasitoids exhibited non-significant correlation with weather parameters and highly significant positive correlation (r=0.976**) with egg counts of H. armigera. Multiple linear regression analysis showed that 77 per cent (R-2=0.77) variability in larval population was accounted by weather parameters particularly maximum temperature, morning and evening relative humidity.