Population dynamics of Helicoverpa armigera (Hubner) hardwick and Spodoptera litura (Fabricius) on groundnut in relation to weather parameters

The investigation on population dynamics of Helicoverpa armigera (Hubner) Hardwick and Spodoptera litura (Fabricius) infesting groundnut var. GG 20 was undertaken at Anand Agricultural University, Anand during summer, 2011–2012. The activity of H. armigera and S. litura began in 1^st week of March and 4^th week of February, respectively and continued up to 3^rd week of May, with a peak activity during 16^th standard week i.e. 3^rd week of April. The larval population of both pests showed significant positive i.e. correlation with maximum, minimum and mean temperature, morning, evening and mean vapor pressure deficit and evaporation, while significant negative association with morning, evening and mean relative humidity. The leaf damage by both pests showed significant positive correlation with maximum, minimum and mean temperature, morning, evening and mean vapour pressure deficit, morning and mean vapor pressure and with evaporation.