Effectiveness of Some Bio-pesticides in Managing Major Lepidopteran Insect Pests of Cabbage (Brassica oleracea var. capitata L.)

Aims: The study aimed to evaluate the efficacy of some bio-pesticides applied against major insect pests of cabbage.

Study Design: With three replications, the experiment was set up in a Randomized Complete Block Design (RCBD).

Place and Duration of Study: The experiment took place in the Sher-e-Bangla Agricultural University's experimental field in Dhaka, Bangladesh, from October 2019 to January 2020.

Methodology: Seven treatments, viz. T1 (Abamectin 1.2EC @ 1 ml/L of water); T2 (Azadirachtin 1EC @ 1 ml/L of water); T3 (Potassium salt of fatty acid @ 1 ml/L of water); T4 (Spinosad 45SC @ 1 ml/L of water); T5 (Bacillus thuringiensis @ 1 ml/L of water); T6 (Abamectin + Bacillus thuringiensis @ 1 ml/L of water) and T7 (untreated control) were used. All the treatments were applied at ten days interval.

Results: Among the management practices, the lowest mean leaf infestation by cabbage caterpillar (6.00 leaves/5 plants) and diamondback moth larvae (4.48 leaves/5 plants) was found in Spinosad 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 diamondback moth larvae (8.93 leaves/5 plants) was found in un-treated plot. The lowest cabbage head infestation (21.37%) was recorded in Spinosad treatment, that gave the highest yield of cabbage (36.40 t/ha) followed by Abamectin (34.07 t/ha).

Conclusion: From the above study it was found that, the treatment T4 comprised of Spinosad 45SC @ 1 ml/L of water at 10 days interval produced the highest performance compared to all other treatments used under the present study.