Efficacy of Beauveria bassiana in combination with NeemAzalT/S® on the whitefly Bemisia tabaci Hemiptera: Aleyrodidae and its natural enemies

The cotton whitefly, Bemisia tabaci, is an important pest of cotton. Because of resistance development in B. tabaci populations to different classes of insecticides, application of alternative compounds is of high importance in IPM programmes. In the present study, effects of Beauveria bassiana (EUTP105 Isolate) alone or in combination with NeemAzal-T/S® and Tiacloprid (Calypso 480 SC) on the eggs and nymphs of B. tabaci and pupae of its parasitoid Eretmocerus mundus Mercet (Hymenoptera: Aphelinidae) were evaluated in field and laboratory conditions. The LC50 values of B. bassiana, NeemAzal-T/S and Calypso against eggs and nymphs of B. tabaci were 1.36×109 conidia ml-1, 6.83 mg L-1 AZA, 0.28 ml l-1 and 1.14×107 conidia ml-1, 6.00 mg L-1 AZA and 0.15 ml L-1, respectively. The LC50 values of B. bassiana, NeemAzal-T/S and Calypso against pupae of E. mundus were 1.30×1010 conidia ml-1, 36.90 mg L-1 AZA and 0.61 ml L-1, respectively. In the laboratory conditions, efficacy of B. bassiana + NeemAzal-T/S on nymphs of the pest was higher than that of B. bassiana, and they caused the lowest mortality in the parasitoid pupae. In the field conditions at 3 days after treatment (DAT), the highest mortality of eggs (42.73%) and nymphs of the pest (89.57%) and pupae of the parasitoid (13.76%) occurred in Calypso. At 7 DAT, NeemAzal-T/S had the highest efficacy (86.52%) on nymph, which was not significantly different to Calypso (76.91%). At 14 DAT, the highest mortality on eggs (18.26%) and nymphs of the pest (46.39%) as well as pupae of the parasitoid (3.25%) were observed in NeemAzal-T/S. Based on the field results, NeemAzal-T/S and B. bassiana can be used as effective and environmentally safe alternatives for chemical insecticides in management of B. tabaci in cotton fields, either alone or in combination.