A supervised residue trial of deltamethrin in mango

The use of chemical pesticides in agriculture has resulted in their contaminations in the produce. Health conscious importing countries have begun to impose strict compliance to international standard of food safety. MRLs is a food safety scheme set up by CODEX, an international organization, to regulate pesticide residues in agricultural produce. In absence of MRLs, the importing countries are at liberty to set standard, normally at zero level tolerance. This has often resulted in trade barrier. In Malaysia, unfortunately, MRLs are not available in many agricultural crops. This has raised great concerns and the authorities view with urgency for remedial action. An attempt was thus made to study the declining deltamethrin residues in mango with the purpose of establishing MRL value. This trial was conducted at MARDI Research Station in Bukit Tangga of Kedah during 2004 crop season. Two plots having 60 mature mango trees each were selected and treated with deLtamethrin at Ix and 2x the manufacturer recommended rates (lx =11.2g a.i./ha) respectively. Deltamethrin is an insecticide commonly used in mango to control fruit flies, leaf cutters and beetles. The insecticide was applied with a motorized sprayer at weekly intervals until 14 days before fruit harvesting. Mango samples (2 kg) were randomly collected from the experimental plots at -1, 0, 1,3, 7 and 14 days after the last spray. Analytical method of deltamethrin was established and validated prior to actual analysis. Satisfactory recoveries ranged from 70 to 98% were obtained for the fortified mango samples suggesting that the analytical method was effective. Results of mango fruit analysis showed low levels of deltamethrin residue ranging from 0.0048 to 0.0091 mg/kg for both treatments. Higher residues were detected at 2x rate, as expected, but both rates exhibited similar declining trends over time. Negligible level of residues was detected after 1 t03 days of spraying indicating that deltamethrin dissipated rapidly. It was concluded that deltamethrin produced no or negligible residue in mango if it was used in accordance to label.