Incidence of white fly (Bemisia tabaci Genn.) and their sustainable management by using biopesticides

Ladysfinger (Abelmoschus esculentus L.) (Moench) is susceptible to various pests of which white fly (Bemisia tabaci Genn.) causes heavy damage. The pest was active throughout the growing period with a peak population (3.98 white fly /leaf) and (4.33 /leaf) during 20rd SMW (middle of May) in the pre-kharif crop and during 42nd -43rd SMW (middle of October) in the post kharif crop respectively. Sudden fall of population was found during July because of heavy rains. White fly showed non-significant positive correlation (p=0.05) with maximum temperature, minimum relative humidity whereas non-significant negative correlation with maximum relative humidity and significant negative correlation with weekly total rainfall. This study evaluated the efficacy of extracts from plants such as Polygonum hydropiper L. and Pongamia pinnata (L.), microbial insecticides like spinosad 45 SC (Saccharopolyspora spinosa Mertz & Yao) and Beauveria bassiana Vuillemin against B. tabaci infesting ladysfinger during the post-kharif season. Imidacloprid was the most effective treatment followed by the microbial insecticide spinosad. Satisfactory white fly control (> 50% population suppression) was achieved with extract of Polygonum plants (5% concentration ) and spinosad. The Polygonum extract was very effective against the white fly, achieving more than 60 % mortality at 3 and 7 days after spraying. Plant extracts and microbial insecticides of biological origin (biopesticides) have less or no hazardous effects on human health and the environment, therefore they can be incorporated in IPM programmes and organic farming in vegetable cultivation