RISK ASSESSMENT OF CERTAIN PESTICIDES USED ON GRAPES UNDER THE EGYPTIAN ENVIRONMENTAL CONDITIONS

Abstract

The aim of this study is estimate of the environmental risks (risk assessment) for imidacloprid insecticide and myclobutanil fungicide on table grape for local use or export, also determination of preharvest intervals (PHI) in order to maintain human health and to avoid damage to the various environmental components biotic and abiotic. In addition to estimating the optional coefficient of the pesticide between the target pests (aphids) and beneficial insects (Apis melifera and Trichogramma). 1. Residues of imidacloprid and myclobutanil in/on grape and soil under field conditions: Residues and degradation percentages of insecticide imidacloprid in/on grape (leaves and fruits) were investigated. The initial residue deposits, which remained on grape leaves and fruits two hours after treatment were 35.66 and 7.04 mg kg-1, respectively. These amounts decreased to 28.16 and 5.92 mg kg-1 one day after the application indicating degradation percentages of 21.04 and 15.90%, respectively. Residues of imidacloprid in/on grape (leaves and fruits) were gradually decreased to 19.52, 11.84, 6.40, 5.12, 2.88 and ND mg kg-1 corresponding degradation percentages of 45.26, 66.80, 82.05, 85.64, 91.92 and ≈ 100% (leaves) and 4.32, 2.44, 1.64, 1.28, 0.32 and ND mg kg-1corssponding degradation percentages of 38.64, 65.34, 76.71, 81.82, 95.45and ≈ 100% (fruits) after 3, 7, 10, 13, 16 and 21 days of application, respectively. Examination of the considered criteria represented by the established regression lines, i.e. slope, degradation constant (K) and RL50, RL90 proved differences in persistence behavior of the targeted pesticides. The imidacloprid degradation constant (K) values are 0.152 and 0.169 in/on grape (leaves and fruits), respectively. As for RL50, RL90 and PHIs values, imidacloprid showed 4.12, 13.42 and 21.95 days and 5.13, 13.41 and 11.96 days in/on grape leaves and fruits, respectively. These results indicated that the same degradation behavior of imidacloprid insecticide in/on grape leaves and fruits. Data also indicated that despite the low