FIELD EVALUATION OF SOME BIORATIONAL INSECTICIDES AGAINST MAJOR INSECT-PESTS OF CABBAGE AND THEIR IMPACTS ON BENEFICIAL ARTHROPODS

Abstract

The experiment was conducted in the experimental field of Sher-e-Bangla Agricultural University, Dhaka, Bangladesh, during the period from October, 2018 to March, 2019 to evaluate biochemical insecticides applied against major insect pests of cabbage. The treatments were T 1 : flubendiamide (Belt 24 WG); T 2 : spinosad (Success 2.5SC); T 3 : emamectine benzoate (Proclaim 5G); T 4 : farmer’s practice (cypermethrin 10 EC); T 5 : untreated control (no pesticides). The experiment was laid out in a Randomized Complete Block Design (RCBD) with three replications. Data were collected on the insect pest species associated with cabbage crop along with their nature of damage, seasonal incidence, damaging stage, cabbage head length and diameter, yield and data on natural enemies. A statistically significant variation was recorded in terms of all the characters related to growth and yield quality. In terms of leaf infestation by cabbage semi-looper at 20 DAT the highest number (12) of leaf infested by semi-looper was for Untreated control and lowest (4) infestation was observed for flubendiamide (Belt 24 WG). Significant variations were observed among different number of treatments of cabbage semi-looper at 20 DAT the highest (11.66) infestation by Cabbage semi-looper was observed for Untreated control and lowest (6.66) were found for flubendiamide (Belt 24 WG). At 20 DAT the highest (5.33) infestation by Cabbage cutworm was for Untreated control and lowest (2.66) were for flubendiamide (Belt 24 WG). At 20 DAT the highest (16) infestation by Cabbage diamondback moth larvae was for Untreated control and lowest (12) were for flubendiamide (Belt 24 WG). In terms of number of field spiders at 20 DAT, there was no significantly variation found among the treatments. For Lady bird beetle, at 20 DAT, there was no significantly variation found among the treatments. But at 60 DAT the highest (6.66) number of lady bird beetle was observed for untreated control. The highest diameter of cabbage head (22.2cm) was achieved from flubendiamide (Belt 24 WG) and lowest diameter (15.5cm) of cabbage was collected for untreated control. The highest height of cabbage head was achieved from flubendiamide (Belt 24 WG) (11.3cm) and lowest diameter of cabbage for untreated control (6.5cm) and the highest yield (19.97 ton/ha.) of cabbage head was achieved from flubendiamide (Belt 24 WG) and lowest yield (18.22 ton/ha.) of cabbage was collected for untreated control. Number of beneficial Arthropods as natural enemies, was also recorded and data suggested relatively low effect on natural beneficial Arthropods.