How does carbofos affect bedbugs? - briefly
Carbofos, an organophosphate insecticide, inhibits acetylcholinesterase in bedbugs, leading to neurotoxicity, paralysis, and rapid mortality. Repeated exposure can lower infestation levels, though resistance may emerge over time.
How does carbofos affect bedbugs? - in detail
Carbofos, an organophosphate insecticide, disrupts nervous function in Cimex lectularius by irreversibly inhibiting acetylcholinesterase. The resulting accumulation of acetylcholine produces continuous nerve impulse firing, leading to muscular paralysis and death. Acute toxicity is high; laboratory LD₅₀ values for adult bedbugs range from 0.5 µg insect⁻¹ to 1.2 µg insect⁻¹ depending on formulation and exposure method.
Sub‑lethal exposure produces measurable physiological and behavioral changes:
- Reduced feeding activity within 24 h of contact.
- Diminished locomotor speed and impaired righting reflex.
- Decreased oviposition rates and lower egg viability.
- Delayed development of nymphal instars.
Repeated applications can select for enzymatic resistance. Populations exposed to sub‑optimal doses often exhibit elevated carboxylesterase activity, which hydrolyzes the active compound and restores acetylcholinesterase function. Resistance management therefore relies on rotating carbofos with chemistries that act on alternative targets, such as pyrethroids or neonicotinoids, and maintaining application concentrations above the established minimum effective dose.
Environmental persistence influences efficacy. In indoor settings, carbofos residues degrade with a half‑life of approximately 7–10 days on porous surfaces, extending to 14–21 days on non‑porous substrates. Residual activity provides a secondary kill window, reducing reinfestation risk when applied according to label‑specified coverage rates (0.02–0.04 g active ingredient m⁻²).
Overall, carbofos exerts rapid lethal action through acetylcholinesterase inhibition, produces dose‑dependent sub‑lethal effects that impair feeding and reproduction, and can drive resistance if misused. Proper dosage, rotation with unrelated modes of action, and awareness of residue decay are essential for sustained control of bedbug infestations.