Population dynamics of Bemisia tabaci in okra

Studies on population dynamics of whitefly Bemisia tabaci on okra crop in Delhi revealed two distinct peaks during 2015 (MSW 30, 21.67 whitefly/3 leaves and MSW 36, 17.33 whitefly/3 leaves, respectively) and 2016 (MSW 32, 19.67 whitefly/3 leaves and MSW 36, 14.67 whitefly/3 leaves, respectively). The observations revealed that rainfall (with correlation coefficients of-0.493** and-0.678** during 2015 and 2016, respectively) as the most important predictor of population among the abiotic factors evaluated. Both the generalist predators (biotic factors) were found highly correlated and well fitted in the prediction models. Results also revealed that rainfall, coccinellids and spider population jointly had a significant impact on B. tabaci population buildup in okra. Validation tests for the prediction models showed that the optimized prediction model Y= 27.86413 + 0.04872(X5)-3.1155(X7) (R2= 0.766**) and Y= 21.72667 + 0.0209(X5)-3.48292(X7) + 1.26738(X8) (R2=0.781*) predicted B. tabaci population reasonably well. These models could be used for decision making in IPM, but subject to validation to improve their predictability.