The residual behavior of abamectin (Vertimec 1.8% EC), chlorpyrifos (PestBan 48% EC), and pyriproxyfen (Admiral 10% EC) in cucumber fruits and leaves under greenhouse conditions was investigated. The pesticides were applied as foliar sprays at recommended doses: 0.5, 2 and 0.5 ml/liter for abamectin, chlorpyrifos, and pyriproxyfen, respectively. After treatment, cucumber fruits were sampled in triplicate at intervals of two hours (initial), and 1, 3, 6, 9, 12, and 15 days post-application. Residues were extracted using the QuEChERS method and analyzed by HPLC-UV for abamectin and pyriproxyfen, andGC-FPDfor chlorpyrifos.
The study found that all three pesticides dissipated over the 15 days post-application, though chlorpyrifos residues were higher in the fruits compared to pyriproxyfen and abamectin. Initial pesticide levels in cucumber leaves were also higher than in fruits. The calculated half-life(t½)in cucumber fruits was 1.66, 1.48 and 2.09 days for abamectin, chlorpyrifos, and pyriproxyfen, while in leaves the half-lives were 2.82, 3.08, and 4.06 days, respectively. Dissipation percentages in residue amounts were higher in cucumber fruits than leaves. Residue levels in cucumber fruits exceeded the maximum residue limits (MRLs) up to 3 days for abamectin, and up to 6 days for both chlorpyrifos and pyriproxyfen after spraying, therefore the pre-harvest intervals (PHI) for safe consumption were determined to be 6 days for abamectin, and 9 days for chlorpyrifos and pyriproxyfen. Washing cucumber fruits with tap water, 10% acetic acid, or 1% sodium bicarbonate for 10 minutes significantly reduced pesticide residue levels. Overall, the residues posed a low health risk to consumers.