How does dichlorvos act on fleas? - briefly
Dichlorvos, an organophosphate insecticide, irreversibly blocks acetylcholinesterase, causing excess acetylcholine at neural junctions, which induces uncontrolled muscular activity, paralysis, and rapid mortality in fleas. The effect manifests within minutes of exposure, providing swift control of infestations.
How does dichlorvos act on fleas? - in detail
Dichlorvos, an organophosphate compound, penetrates the flea’s cuticle after topical application or environmental exposure. The molecule reaches the hemolymph, where it encounters the enzyme acetylcholinesterase (AChE). By forming a covalent bond with the serine residue in the active site, dichlorvos irreversibly inhibits AChE activity. This inhibition prevents the hydrolysis of acetylcholine, leading to excessive accumulation of the neurotransmitter at synaptic junctions.
The resulting cholinergic overload produces continuous stimulation of nicotinic and muscarinic receptors within the flea’s nervous system. Motor neurons fire uncontrollably, causing tremors, loss of coordination, and eventual paralysis. Respiratory muscles cease functioning, and the insect succumbs within minutes to a few hours, depending on dose and environmental temperature.
Key physiological impacts include:
- Rapid cuticular absorption across all developmental stages (egg, larva, adult);
- Systemic distribution through hemolymph, ensuring exposure of central and peripheral nervous tissue;
- Persistent AChE inhibition leading to irreversible neural failure;
- Absence of metabolic detoxification pathways in fleas, which accelerates lethality.
The speed of action correlates with concentration gradients; higher ambient concentrations produce faster knock‑down. Residual activity persists on treated surfaces for several days, providing ongoing exposure to newly emerging fleas. However, prolonged use may select for resistant populations possessing modified AChE isoforms or enhanced detoxifying enzymes.
Safety considerations mandate restricted application to indoor environments, avoidance of direct contact with mammals, and adherence to labeled exposure limits. Proper ventilation and protective equipment minimize occupational risk while maintaining effective flea control.