Influence of some new insecticides on sweetpotato whitefly, Bemisia tabaci and American serpentine leafminer, Liriomyza trifolii and their residues in cucumber fruits

Toxicity of three modern insecticides (etofenprox, imidacloprid and spirotetramat) was tested against the adults of sweetpotato whitefly, Bemisia tabaci and American serpentine leafminer, Liriomyza trifolii under greenhouse conditions. The results showed that imidacloprid was the most toxic against the adults of sweetpotato whitefly and American serpentine leafminer followed by etofenprox and spirotetramat after three treatments. The percent of corrected efficacy of sweetpotato whitefly was 98, 93.5, and 1.7%, respectively. The percent of adults reduction was 98.4, 95.7 and 16%, respectively. The corresponding results with American serpentine leafminer were 78.7, 57.1 and 18.4%, respectively. The percent of leafmines reduction was 77, 54.5 and 11.7%, respectively. Dissipation rate of recommended field rate of all tested insecticides in cucumber fruits was determined after the first, second and third applications. The residue level in cucumber fruits was increased after 24 hrs from the third treatments to 0.94, 1.99 and 1.02 mg/kg for etofenprox, imidacloprid and spirotetramat, respectively. The dissipation rate of all tested insecticides was 100, 91 and 100% for etofenprox, imidacloprid and spirotetramat, respectively, after 7 days of the third treatment. The results showed that imidacloprid was suitable for insect control in cucumber fields (high efficacy against pests and low residues) compared with etofenprox and spirotetramat. The results recommended that a waiting period of 3 days is sugge