How do insecticides work on fleas? - briefly
Insecticides kill fleas by disrupting nerve transmission, usually by blocking sodium channels or inhibiting acetylcholinesterase, which causes uncontrolled firing, paralysis, and death. Certain agents also damage the respiratory system or desiccate the insect through contact with its cuticle.
How do insecticides work on fleas? - in detail
Insecticidal compounds eliminate fleas by disrupting essential physiological processes. The primary mechanisms are neurotoxicity, interference with development, and metabolic inhibition.
- Neurotoxic agents – pyrethroids and organophosphates bind to voltage‑gated sodium channels or inhibit acetylcholinesterase, respectively. Pyrethroids force prolonged channel opening, causing uncontrolled nerve firing and paralysis. Organophosphates prevent the breakdown of acetylcholine, leading to continuous synaptic stimulation and eventual respiratory failure.
- Nicotinic agonists – neonicotinoids attach to insect nicotinic acetylcholine receptors, producing persistent excitation and paralysis without affecting mammalian receptors.
- Insect growth regulators (IGRs) – compounds such as methoprene and pyriproxyfen mimic juvenile hormone or block chitin synthesis. They prevent larvae from molting, halting population development.
- Systemic agents – oral or topical products containing isoxazolines circulate in the host’s blood. Fleas ingest the drug during feeding; the compound blocks GABA‑gated chloride channels, leading to hyperexcitation and death.
Delivery routes determine exposure. Contact insecticides act through direct skin or fur contact; insects absorb the chemical through the cuticle. Ingested insecticides rely on the flea’s blood meal to introduce the toxin. Systemic formulations provide continuous protection as long as therapeutic concentrations persist in the host’s bloodstream.
Resistance arises when flea populations develop enzymatic pathways that detoxify the active ingredient or alter target site affinity. Rotating chemicals with different modes of action mitigates selection pressure and prolongs efficacy.
Effective flea control therefore depends on selecting an insecticide whose biochemical target aligns with the pest’s vulnerability, applying it in a manner that ensures adequate uptake, and managing resistance through strategic product rotation.