What is the primary active ingredient in most insecticides?

The primary active ingredient in most insecticides is generally categorized as either pyrethroids or organophosphates. Pyrethroids are synthetic chemicals modeled after natural insecticides derived from chrysanthemum flowers. They work by affecting the nervous system of insects, leading to paralysis and death. Organophosphates, on the other hand, are a class of chemicals that disrupt the transmission of nerve signals in insects by inhibiting an enzyme called acetylcholinesterase, which is crucial for proper nerve function.

Both classes are widely used in residential and commercial pest control due to their effectiveness against a broad spectrum of pests and their relatively low toxicity to humans and pets when used according to label instructions. This makes them a common choice in the formulation of insecticides.

Other options, while valid and used in specific contexts, do not represent the primary active ingredients used in the majority of commercial insecticide products. For example, anticoagulants are primarily used in rodenticides rather than insecticides, natural oils may serve as insect repellents or for specific niche applications and chlorinated hydrocarbons, though historically significant, have been largely phased out of use due to environmental and health concerns.