DETERMINATION OF PRE-HARVEST INTERVAL OF SYNTHETIC PYRETHROID INSECTICIDE IN EGGPLANT THROUGH THE STUDY OF CHEMODYNAMICS IN BANGLADES

ABSTRACT: A chemodynamics study was undertaken to determine the pre-harvest interval (PHI) of the selected synthetic pyrethroid insecticide (cypermethrin 10EC) in eggplant. The study was conducted in the experimental farm and Pesticide Toxicology Laboratory of the Department of Entomology, Bangabandhu Sheikh Mujibur Rahman Agricultural University (BSMRAU), Gazipur during summer (February-June 2016). The fate of cypermethrin after application, consisted of receiving insecticide by eggplant plant and disseminating it to air and soil was evaluated. Cypermethrin residue was determined from eggplant and soil sample sprayed @ 1ml l-1 of water in the field and it was 0.022 mg/kg up to 7 days after spraying (DAS) and 0.107ppm up to 5 DAS individually. The quantities were above the CODEX maximum residue limit (MRL) up to 3 DAS (0.408 ppm & 0.461 ppm) both in eggplant and soil samples. When cypermethrin 10EC sprayed @ 2ml l-1 of water, the residue of cypermethrin was detected in soil and eggplant samples up to 0.028ppm at 7 DAS and 0.030ppm at 10 DAS, separately, where MRL exceeds at 5 DAS (0.421ppm) for soil sample and at 3 DAS (0.452ppm) for eggplant sample, respectively. The residue degradation observed at early period was lower (42.18% in eggplant and 27.95% in soil at 1 DAS, when cypermethrin was applied @ 1ml l-1 of water and conversely 40.83% in eggplant and 56.02% in soil at 1 DAS, when cypermethrin was applied @ 2ml l-1), however, at the later period it was higher (97.80%in eggplant and 89.13%in soil when cypermethrin was applied @ 1ml l-1 of water, these were 97.03% in eggplant and 98.67% in soil when cypermethrin was applied @ 2ml l-1 of water). The Pre-Harvest Interval (PHI) was found 04 days for cypermethrin in eggplant. 

Keywords: Cypermethrin, chemodynamics, eggplant plant, pesticide residue.