Cypermethrin Chemodynamics in Okra Crop Agro-Ecosystem in Bangladesh

Cypermethrin is a non-systemic insecticide widely used for controlling okra shoot and fruit borer infestation in Bangladesh. During its application in the okra field by a knapsack sprayer, cypermethrin not only targets the plant but also disperses into the soil, air, and other environmental components. This study investigates the dissipation pattern of cypermethrin at different growth stages of the okra crop through field research, along with a laboratory analysis to determine cypermethrin residues in fruit and soil. The highest deposition of cypermethrin (58.2±3.6%) was observed at 105 days after sowing (DAS), and the lowest (47.3±2.3%) at 45 DAS. Drift loss in the air ranged from 4.65±0.8% to 7.85±0.4%, while soil drift loss was highest at 45 DAS (48.05±2.7%) and lowest at 120 DAS (36.25±0.7%). Residue analysis showed that cypermethrin levels in fruit and soil samples exceeded maximum residue limits (MRLs) up to three days post-spraying (0.862 ppm in fruit) and five days post-spraying (0.554 ppm in soil) at 1 ml/L concentration. At 2 ml/L, fruit samples exceeded MRLs up to seven days (0.668 ppm) and soil samples up to five days (0.653 ppm).