EFFECT OF BIOPESTICIDES ON MAJOR INSECT PESTS OF CABBAGE AND THEIR NATURAL ENEMIES

Abstract

The study was conducted in the central farm of Sher-e-Bangla Agricultural University, Sher-e-Bangla Nagar, Dhaka during October 2018 to March, 2019 to know the effect of biopesticides on major insect pests of cabbage and their natural enemies. Six treatments were used under the experiment. They were T 1 = Spinosad, T 2 = SNPV (Spodoptera litura nuclear polyhedrosis virus), T 3 ii = Spodolure trap, T 4 = Spodolure trap + Spinosad spray, T 5 = Spodolure trap + SNPV spray and T 6 = untreated control. The experiment was laid out in a Randomized Complete Block Design (RCBD) with four replications. Results revealed that the lowest number of infested leaves by flea beetle (0.33/ 5 plants), tobacco cutworm (0.33/ 5 plants), semilooper (0.33/ 5 plants), diamondback moth (1.33/ 5 plants) and aphid (7.50/ 5 plants)

were

found in T 4 treatment (Spodolure trap + Spinosad). In case of incidence of natural enemies, the highest number of lady bird beetle (8.00/plot) and spider (8.60/plot) was also found from T 4 (Spodolure trap + Spinosad) treatment compared to untreated control. The highest percentage of healthy plants (91.67%), highest weight of healthy cabbge head plant -1 (1.20 kg), marketable cabbage head plot

(19.48 kg) and marketable yield of healthy cabbage head (45.08 t ha ) was found in T 4 (Spodolure trap + Spinosad) treatment. Spodolure trap in combination with Spinosad spray may be considered as effective practice for the management of cabbage insect pests and conservation of natural enemies.