(LD) the amount of an insecticide, its active ingredient, or other toxicant necessary to kill a specified proportion of an insect population —note LD₅₀ signifies a dose (estimated or measured) that kills half the insect population in question; LD₉₉ is the highest lethal dose since no dose can guarantee a 100 percent effect —see median effective dose This definition last updated 07/11/2008