Population Dynamics of Thrips, Scirtothrips dorsalis Hood Infesting Chilli as Influenced by Biotic and Abiotic Parameters in Southern Karnataka

Population dynamics of thrips, Scirtothrips dorsalis Hood as influenced by biotic and abiotic factors on chilli crop under Bengaluru conditions (IIHR, Hessaraghatta & GKVK) and Kotagal (near Chintamani) was studied during Kharif and Rabi seasons of 2015-16 and 2016-17. During Kharif season of 2015-16, peak population of thrips was 28.87 thrips / plant when the crop age was 83 days old (42nd Std week), coincided with II FN of October. Also, a second peak (11.53 thrips plant-1) on Kharif crop was during mid – December (49th Std week), under GKVK condition also first and second peaks were recorded during October and end of November, respectively. During 2016-17 thrips incidence was relatively low (3 thrips) at th Std week and modest (8.33) during early December (Std week 48) when the crop nearing maturity. A more similar trend was observed under Chintamani condition. On Kharif crop of 2015-16, a more evident peak (26.33 thrips) was during I FN of March (11th Std week) when the crop age was 94 days under IIHR conditions. Simillarly, under GKVK and Chintamani conditions also the peak thrips population was recorded during mid-March i.e., 53.30 and 40.60 thrips plant-1, respectively. Similar trend was recorded in 2016-17 Kharif season, thus, over all activity of chilli thrips on Kharif crops across three locations was more prominent during February-March period. overall influence of different weather parameters across three different locations indicated maximum temperature, bright sunshine hours, evaporation and natural enemies during the cropping period significantly influenced the buildup of thrips, while minimum temperature, rainfall, wind speed, and crop age (phenology) were observed to affect the thrips population adversely.