An experiment was carried out at the field of Entomology, Bangladesh Agricultural University, Mymensingh to determine the extent of damage of bean plants by aphid, Aphis craccivora Koch. and its biorational management. Efficacy of biorationals viz. Neem oil (2ml/l), Mahogany oil (2ml/l), Karanja oil (2ml/l), Abamectin (1ml/l), Spinosad (1ml/l), Emamectin benzoate (1g/l) and Lufenuron(1ml/l) were evaluated against bean aphid, A. craccivora Koch. The experiment was laid out in randomized complete block design with three replications of each treatment. Three sprays of the treatments were made at 15 days interval. The highest mean percentage of infested twig (82.57), flower (71.38), and pod (79.51) were found in untreated plants at 100 days after seed sowing (DAS). But at 60 DAS the lowest average percent infestations were found 26.08, 34.28 and 33.33 in twig, flower and pod, respectively. The highest reduction of aphid on the twigs was found in Abamectin (70.14%) followed by Spinosad (64.14%) and Neem oil (59.16%). Similarly the highest reduction of aphid was in Abamectin (79.02%) followed by Spinosad (73.95%) and Neem oil (69.22%) on the flowers. In both cases the lowest reduction of aphid was noticed in Karanja (39.24% & 48.70%) followed by Mahogany oil (40.72% & 54.00%). Reduction of aphid population on pods was the highest in Abamectin (86.97%), followed by Spinosad (81.97%) and Neem oil (75.1%) after 1st spray. The lowest reduction of aphid was found in Karanja oil (53.16%) followed by Mahogany oil (61.17%). After 2nd and 3rd sprays similar trend in percent reduction of aphid population was observed. Results also revealed that among the selected insecticides, Abamectin, Spinosad and Neem oil provided better protection of plants against bean aphid. The maximum increase of yield over control was found in Abamectin (9.37t/ha) followed by Spinosad (8.36 t/ha) and Neem oil (7.36 t/ha) after all sprays respectively.
Key words: Botanical, Spinosad, Emamectin benzoate, Abamectin, Lufenuron, Management
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