Seasonal Incidence of Scirtothrips dorsalis and Bemisia tabaci on Chilli with Studies on Comparative Efficacy of Insecticides and Botanical Oils

The study conducted at Sam Higginbottom University of Technology and Sciences in Prayagraj during the 2019 and 2020 kharif seasons provided comprehensive insights into insect population dynamics and insecticide efficacy against thrips and whiteflies in chilli cultivation. Key findings revealed significant pest population fluctuations, with thrips peaking at 16 per plant during the 43rd Standard Meteorological Week (SMW) in late October for both years. Whitefly populations reached up to 17.6 per plant, peaking during the 44th week in 2019 and the 43rd week in 2020, both in late October. Correlation analyses showed significant negative relationships between insect populations and temperature, wind velocity, and rainfall, while a positive correlation was observed with sunshine duration. Multiple linear regression models demonstrated that weather parameters collectively explained 69.8% and 70.4% of thrips population variability in 2019 and 2020, respectively, and 87.7% and 17.2% of whitefly population variability. Stepwise regression models revealed that in 2019, maximum temperature and rainfall jointly accounted for 46% of pest population variability. In 2020, the addition of wind velocity to these factors explained 83% and 56% of variability in thrips and whitefly populations, respectively. Insecticide efficacy evaluation showed acetamiprid as most effective against thrips (92.14% reduction) and imidacloprid against whiteflies (88.89% reduction). Thiamethoxam and imidacloprid demonstrated comparable effectiveness. Economic analysis highlighted imidacloprid's superiority, providing effective pest control, the highest chili yield, and the best cost-benefit ratios (1:8.30 in 2019 and 1:5.38 in 2020).