Ram B Paneru, Sunil Aryal and Yagya P Giri
Entomology Division, Khumaltar, Lalitpur

Abstract

Toxic residue level of chemical insecticides in cauliflower curds treated with dichlorovos (Nuvan 76% EC), endosulfan (Thiodane 35% EC), fenvalerate (Fen-fen 10% EC), and cypermethrin (Super Killer 10% EC) was analyzed through gas-chromatography (GC) in the Entomology Division during 2008/09. The cauliflower plants at curd formation stage were treated with four consequent sprays (at 12 days interval) of above insecticides each using recommended dose. The curd samples were taken for the analysis from the treated plots at 3, 7, 15 and 25 day after last treatment. Standard procedures were followed for residue extraction, purification and concentration of targeted insecticides for analysis through GC. The analysis showed that the residual level of dichlorovos, endosulfan, fenvalerate and cypermethrin varied from 0.0027 to 0.004, 1.3918 to 0.0096, 4.8292 to 0.8585 and 2.7401 to 0.1650 ppm respectively from 3 to 25 days. Residue of Nuvan was maximum < residue limit (MRL) at 24 hours of its application, and it was < average daily intake (ADI) level at 3 days onward. The residue of Thiodane was < MRL in all days but it was > ADI up to 25 days. Likewise, residue of Fen-fen was > its MRL and ADI level up to 25 days. The residue of cypermethrin was > MRI level up to 3 days and > is ADI value up to 25 days. The analyzed data indicated that the consumption of cauliflower treated by Thiodane, Fen-fen and Superkiller is not safe up to 25 days if four consequent sprays of these insecticides are given. Amongst the insecticides, rate of degradation of Nuvan was the highest, and that of Fen-fen was the least. Residual level of insecticides in the curds of commercial production areas could be much more than this because farmers used to apply such insecticides frequently in higher doses than recommended, and give little attention to waiting period for harvesting after application of insecticides.

Keywords: Cauliflower curds, Degradation, Insecticide, Residue, Toxicity