EFFECTIVENESS OF SOME BIOPESTICIDES IN MANAGING MAJOR LEPIDOPTERAN INSECT PESTS OF CABBAGE

Abstract

An experiment was conducted in the experimental field of Sher-e-Bangla Agricultural University, Dhaka, Bangladesh during the period from October, 2019 to January, 2020 to evaluate some biopesticides applied against major insect pests of cabbage. The experiment was laid out in Randomized Complete Block Design (RCBD) with three replications. Seven treatments, viz. T (Abamectin 1.2EC @ 1 ml/L of water at 7 days interval); T 2 ii

1 (Azadirachtin 1EC @ 1 ml/L of water at 7 days interval); T

(Potassium salt of fatty acid @ 1 ml/L of water at 7 days interval); T (Spinosad 45SC @ 1 ml/L of water at 7 days interval); T 5 4 (Bacillus thuringiensis @ 1 ml/L of water at 7 days interval); T (Abamectin + Bacillus thuringiensis @ 1 ml/L of water at 7 days interval) and T 7 6 (untreated control) were used. Among the management practices, the lowest mean infestation of cabbage leaf by cabbage caterpillar (6.00 leaves/5 plants) and diamond back moth larvae (4.48 leaves/5 plants) was found in T treated plot that reduced the highest leaf infestation over control (62.02% and 49.85 % respectively); whereas the highest infestation by cabbage caterpillar (15.80 leaves/5 plants) and diamond back moth larvae (8.93 leaves/5 plants) was found in un treated plot (T 4 ). The lowest mean incidence of cabbage caterpillar (6.82 larvae/5 plants) and diamondback moth (4.87 larvae/5 plants) was found in T that reduced highest incidence over control (50.33% and 51.90% respectively); whereas the highest values of all these parameters were achieved from untreated control treatment (T 4 ).The lowest cabbage head infestation (21.37%) was recorded in T , that gave the highest yield of cabbage (36.40 t/ha) followed by T 1 4 (34.07 t/ha). From the above study it was found that , the treatment T comprised of Spinosad 45SC @ 1 ml/L of water at 7 days interval gave the highest performance compared to all other treatments used under the present study.