Abstract:The larval stage of the mosquitoes, harmful human diseases vectors, are attractive targets for insecticides. Because ecdysteroids show striking similarities in chemical structure with plant growth hormone of brassinosteroids (BR), we proposed that BR biosynthesis inhibitors may interfere the ecdysteroid biosynthesis thereby killing the mosquitoes at the larvae stage. To verify this hypothesis, we screening the larvicidal activity of BR biosynthesis inhibitors developed in our laboratory. The larvicidal activity of BR biosynthesis inhibitors were studied by using a laboratory bioassays against 3rd to 4th in star larvae of Aedesaegypti. M. In conclusion, we found a triazole type new lead compound which displays promising larvicidal activity against Aedesaegypti. Further structure-activity relationships studies may lead to the discovery of new class of insecticide for mosquito control.