Population dynamics and biorational management of sucking insect vectors on chili (Capsicum annuum L.) in Bangladesh

To evaluate population fluctuations in relation to weather parameters and biorational management of sucking insect vectors in chili (Capsicum annuum L.), we conducted a study at the experimental field of Bangabandhu Sheikh Mujibur Rahman Agricultural University, Gazipur, in 2020 and 2021. It has been shown in this study that sucking insects (aphids, jassids, whiteflies, and thrips) were active throughout the study period. The highest count of sucking insect vectors (24.67 aphids, 13.72 whitefly, and 56.56 thrips) in March and (14.83 jassid) in April was recorded at average temperatures of 34–36°C and 31°C, respectively. There was a positive correlation between pest abundance and temperature, relative humidity, and rainfall for all insects, with the exception of a negative correlation between whiteflies and temperature and rainfall. The results of linear regression models showed that abiotic factors contribute to pest abundance levels, with 100R² values of 14.9 (thrips), 46.3 (jassids), 7.1 (whiteflies), and 0.67 (aphids); the results were statistically significant for all models in the case of thrips, jassids, and whiteflies, but not significant in the case of aphids. The most effective treatment was spinosad 45SC, a bacterium-derived pesticide recommended for the control of sucking insect vector complexes in chili. The results from the spinosad-treated plot, in terms of insect counts and corresponding mortality rates, were as follows: aphids (3.68), 68.89%; jassids (3.52), 72.01%; whiteflies (3.00), 66.69%; and thrips (3.40), 69.20%. The results of this study will aid in developing predictive models of different control agents against sucking insect vectors in vegetable crops.