BIOPESTICIDES MITIGATE THE LARVAL POPULATION OF LEPIDOPTERAN INSECTS ON CABBAGE (Brassica oleracea var. capitata L.)

Abstract

The infestation of insect pests has a significant impact on cabbage yield. Lepidopteran insects are one of the most important insect pests in the reduction of cabbage output. The present study aimed to evaluate some biopesticides used against major cabbage insect pests. The experiment was set up in a Randomized Complete Block Design (RCBD) with three replications. There were seven treatments used: 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). All of the treatments were given seven days apart. T4 that reduced the highest incidence over control of cabbage caterpillar and diamondback moth larvae (50.33 % and 51.90 %, respectively) had the lowest mean incidence of cabbage caterpillar (6.82 larvae/5 plants) and diamondback moth larvae (4.87 larvae/5 plants), whereas the untreated control treatment (T7) had the highest values of all these parameters. T4 had the lowest cabbage head infestation (21.37 %) and the maximum cabbage yield (36.40 t/ha), followed by T1 (34.07 t/ha). According to the results of the study, treatment T4 (Spinosad 45SC @ 1 ml/L of water at 7-day intervals) had the best performance of all the treatments tested.