How does chlorpyrifos affect bedbugs? - briefly
Chlorpyrifos, an organophosphate insecticide, inhibits acetylcholinesterase in bedbug nervous systems, causing uncontrolled nerve firing, paralysis, and death. Repeated use can select for resistant strains, diminishing its long‑term effectiveness.
How does chlorpyrifos affect bedbugs? - in detail
Chlorpyrifos is an organophosphate insecticide that inhibits acetylcholinesterase, causing accumulation of acetylcholine at synaptic junctions. The resulting overstimulation of cholinergic receptors leads to paralysis and death in insects.
Laboratory bioassays show that exposure to chlorpyrifos at concentrations between 0.1 and 1 mg L⁻¹ produces 90–100 % mortality in adult bedbugs within 24 h. Nymphal stages are similarly vulnerable, although early instars require slightly higher doses for equivalent mortality. Contact exposure on treated surfaces yields rapid knock‑down, while residual activity persists for 2–3 weeks under typical indoor conditions.
Sub‑lethal exposure disrupts feeding behavior, reduces blood‑meal size, and impairs locomotion. Reproductive output declines by 30–70 % in surviving females, with fewer eggs laid and lower hatch rates. Chronic low‑dose exposure extends developmental time and increases mortality during molting.
Field populations have begun to exhibit resistance. Documented mechanisms include elevated activity of mixed‑function oxidases that detoxify chlorpyrifos, and point mutations in the acetylcholinesterase gene that reduce binding affinity. Resistance management recommends rotating chlorpyrifos with insecticides of unrelated mode of action and integrating non‑chemical controls.
Application guidelines advise applying 0.5 g m⁻² of a 20 % chlorpyrifos formulation to cracks, crevices, and bed frames. Proper ventilation and avoidance of direct skin contact are required to protect occupants. The compound remains effective on porous surfaces for up to 21 days, after which re‑treatment may be necessary.
Regulatory agencies have restricted residential use in several jurisdictions due to potential neurotoxic effects on humans and wildlife. Protective equipment, precise dosing, and adherence to label instructions minimize risks while preserving efficacy against the target pest.