How does Malathion work against bedbugs? - briefly
Malathion, an organophosphate insecticide, inhibits acetylcholinesterase, causing acetylcholine buildup that paralyzes and kills bedbugs. Applied as a spray, it penetrates the cuticle and results in rapid mortality after contact.
How does Malathion work against bedbugs? - in detail
Malathion belongs to the organophosphate class of insecticides. Its efficacy against Cimex lectularius relies on inhibition of acetylcholinesterase, the enzyme responsible for hydrolyzing the neurotransmitter acetylcholine at synaptic junctions. When the enzyme is blocked, acetylcholine accumulates, causing continuous stimulation of cholinergic receptors. The resulting overstimulation leads to paralysis and eventual death of the insect.
The compound penetrates the cuticle of bedbugs through direct contact or residual deposition on surfaces. After absorption, it distributes via the hemolymph to the nervous system. Key stages of the toxic action include:
- Binding of Malathion to the active site of acetylcholinesterase, forming a stable phosphorylated complex.
- Prevention of acetylcholine degradation, producing sustained depolarization of neuronal membranes.
- Disruption of muscular coordination, manifested as tremors, loss of mobility, and inability to feed.
- Fatal metabolic collapse due to prolonged neural excitation.
Resistance may develop through enhanced detoxification enzymes (e.g., carboxylesterases) or target-site mutations that reduce binding affinity. Managing resistance involves rotating chemicals with different modes of action and integrating non‑chemical control measures.
Environmental considerations: Malathion degrades rapidly in sunlight and hydrolysis, producing less toxic metabolites. Proper ventilation and avoidance of direct human skin contact minimize health risks during application.