Temephos

Temephos is an organophosphate insecticide primarily used as a larvicide to control mosquito populations in standing water and other aquatic habitats. It has been widely employed in public health programs to reduce the transmission of diseases such as malaria, dengue, and filariasis by targeting mosquito larvae before they emerge as adults.

The compound acts as a cholinesterase inhibitor, interfering with the normal breakdown of acetylcholine in the nervous system. Temephos may be bioactivated to a more potent oxon form, which enhances acetylcholinesterase inhibition. The resulting accumulation of acetylcholine causes overstimulation of cholinergic nerves, leading to a range of physiological effects in insects and, at higher exposures, in non-target organisms and humans. Common signs of exposure include muscle twitching, salivation, excessive tearing, wheezing, and in severe cases, respiratory distress.

In practice, temephos is applied to larval habitats such as containers, drain pools, irrigation channels, and other stagnant waters where mosquito larvae develop. Applications are typically conducted by trained public health personnel or licensed applicators, following label directions and local regulations to minimize risks to non-target species and the environment.

Safety and environmental considerations are important with temephos. It is toxic to aquatic life and should be used with care near fish, amphibians, and other wildlife. Protective equipment is advised for handlers, and improper use or accidental release into water bodies can disrupt ecosystems. Due to potential resistance and regulatory changes, its use is periodically reassessed in many regions.