Population dynamics and biology of whitefly ( Bemisia tabaci Gennadius ) on sunflower ( Helianthus annuus L.)

Abstract

A sunflower hybrid (KBSH 1) was sown on three different dates of sowing (third week of December, third week of January and third week of February) at Central Research Farm (CRF), BCKV, Gayeshpur and Farmers field. Among the three different dates of sowing, the population of whitefly (Bemisia tabaci Gennadius) (Homoptera: Aleyrodidae) was always higher on first date of sowing followed by intermediate and late sown crop. During first year the whitefly population reached its peak with population load of 5.08, 3.52 and 3.05/leaf at CRF and 6.49, 5.44 and 4.63/leaf at Madandanga farm on second week of February, first week of March and fourth week of March respectively. During second year the whitefly on sunflower, reached its peak with population load of 5.27, 4.45 and 3.71/leaf at CRF and 8.79, 7.29 and 5.21/leaf at Madandanga field on second week of February, first week of March and fourth week of March respectively. Life history of B. tabaci was studied under laboratory condition (ranged 22 to 290C and RH, 75±5%) on sunflower at Plant Health Clinic, BCKV, Nadia, West Bengal. The average developmental period of eggs, first, second, third and fourth instars of whitefly on sunflower were 8.80±1.14, 2.10±0.57, 4.90±0.74, 5.60±0.97 and 6.90±1.29 days respectively, with total nymphal period of 19.40±2.50; Fecundity, 27±2.70 eggs/female; adult longevity (male: 4.30±0.82, female: 5.40±0.97 days). However, the pre-oviposition period lasted for 1.20±0.42 days, oviposition 3.60±0.70 days and post-oviposition 0.60±0.70 days, respectively. Average length for the stages were (mean±SD) egg, 0.22±0.010; first instar, 0.29±0.013; second instar, 0.43±0.024; third instar, 0.69±0.022 and fourth instar, 0.84±0.017 mm respectively.