Toxicity of thiamethoxam/chlorantraniliprole, novaluron, chlorpyrifos-methyl and methomyl against two different larval instars of the cotton leafworm Spodoptera littoralis (Boisd.) on tomato plants

The toxicity of thiamethoxam/chlorantraniliprole, novaluron, chlorpyrifos-methyl and methomyl applied at recommended rates was studied against the cotton leafworm spodoptera littoralis on tomato plants, during the summer seasons of 2010 and 2011 at etay el-baroud agricultural research station, el-beheira governorate. the % mortalities average (initial kill) caused by thiamethoxam/chlorantraniliprole, novaluron, chlorpyrifos-methyl and methomyl were 83.8, 84.8, 91.2 and 87.4%, respectively against 2nd instar of spodoptera larvae, and were 82.5, 77.2, 89.9 and 87.4%, respectively against 4th instar of spodoptera larvae, while %mortality average (residual toxicity) were 86.0, 70.5, 71.9 and 62.6%, respectively against 2nd instar of spodoptera larvae, and were 71.7, 61.9, 67.6 and 56.9%, respectively against 4th instar of spodoptera larvae. from these data it is clear that the two novel tested insecticides have a potent insecticidal activity against both 2nd and 4th instars s. littoralis larvae. results revealed that tested insecticides were more effective on second instar than forth instar and showed significant differences between tested insecticides.