In-vivo efficacy of biopesticides and synthetic insecticides against banana leaf and fruit scarring beetle, Basilepta subcostatum (Jacoby) (Coleoptera: Chrysomelidae)

Evaluation of some biopesticides and synthetic insecticides were carried out to reduce the incidence of banana leaf and fruit scarring beetle, Basilepta subcostatum at three critical stages of banana at Horticulture Experimental Farm of Assam Agricultural University, Jorhat during 2017–18. Among the synthetic insecticides, chlorpyriphos 20 EC @ 1.5 l/ha proved to be the best (63.77, 59.12 and 62.50%) in reducing the beetle population, followed by profenofos 50 EC @ 1.5 l/ha (57.89, 53.19 and 50.69%) and imidacloprid 17.8 SL @ 20 g a.i./ha (54.18, 45.16 and 41.30%) at flower bud initiation, shooting and bunch formation stages, respectively. Among the biopesticides, azadirachtin 0.03 EC @ 2.5 l/ha arrayed itself as best (49.32, 36.93 and 30.01%) over Metarhizium anisopliae (27.27, 35.14 and 40.66%) and Beauveria bassiana (26.95, 33.30 and 38.01%) at flower bud initiation, shooting and bunch formation stages, respectively. Plants bud injected with imidacloprid registered least fruit infestation (8.34%), highest pulp to peel ratio (2.31), fruit weight (142 gm), bunch weight (17.66 kg), yield (78.53 t/ha) and B:C ratio (3.06).