Residue determination of some rational insecticides in tomato fruits and their efficacy on sweet potato whitefly, Bemisia tabaci

Residues of some rational insecticides (etofenprox, imidacloprid and spirotetramat) in tomatoes fruits were determined after three applications. The results showed that the residues of tested insecticides in zero time (after one hour of insecticides treatment) were the maximum. After the first application the residues of these insecticides were 2.62, 0.91 and 0.95 mg/kg for imidacloprid, spirotetramat and etofenprox, respectively. The corresponding results after the second and third applications were 3.14, 0.95 and 0.96; 3.42, 1.06 and 0.86 mg/kg, respectively. After one week intervals the insecticides residues were decreased to 0.089, 0 and 0; 0.009, 0 and 0; 0.18, 0.04 and 0.05 mg/kg, respectively. The dissipation rate after the third application was 94.7, 92.2 and 94.2% for imidacloprid, spirotetramat and etofenprox, respectively. The results showed that imidacloprid has a minimum preharvest interval (PHI) followed by spirotetramat and etofenprox. The PreHarvest Interval (PHI) was 3.8, 5.8 and 6.8 days, respectively. The results showed also, imidacloprid was the most toxic against sweet potato whitefly adults followed by etofenprox and spirotetramat. The reduction percent of whitefly adults was 98.7, 93.7 and 30%, respectively. The results recommended that using of imidacloprid in sweet potato whitefly control was