Organophosphate

Definition

Any of a class of organophosphorus compounds, typically esters of phosphoric acid with the general structure O=P(OR)3, that function as neurotoxic insecticides by irreversibly inhibiting acetylcholinesterase in the nervous system of arthropods and other animals.

Etymology

From 'organo-' (organic) + 'phosphate' (phosphoric acid ester)

Example

Malathion, a widely used organophosphate, controls mosquito larvae in standing water and is applied to livestock to control horn flies (Haematobia irritans), though resistance has evolved in many populations.

Synonyms

• OP
• organophosphorus insecticide

Related Terms

• carbamate
• pyrethroid
• acetylcholinesterase
• insecticide resistance
• cholinergic toxicity
• Integrated Pest Management
• neonicotinoid

Usage Notes

In entomology, 'organophosphate' typically refers to the insecticide subclass rather than the broader chemical class (which includes flame retardants, plasticizers, and nerve agents). The term often appears in contrast to carbamates, which share the same mode of action but have shorter residual activity and reversible enzyme inhibition. Resistance management strategies frequently rotate organophosphates with other chemical classes to delay selection for detoxification mechanisms such as enhanced esterase activity or target-site insensitivity. Toxicity to non-target organisms, including beneficial insects and vertebrates, limits their use in conservation biological control.