Study summary
Emergence and spatial distribution of knockdown resistance in a suburban population of Aedes albopictus
Baltzegar JF, Butler CD, Ding JY, Beeson CM, Reed EMX, Reiskind MH, Burford Reiskind MO
Read the original paper- Study type
- Other
- Year
- 2026
- Published in
- Parasites & Vectors (2026), DOI 10.1186/s13071-026-07519-6
- Evidence strength
- Well-supported evidence
Summary
Longitudinal field-genetic surveillance study tracking how quickly pyrethroid knockdown-resistance (kdr) spread through a suburban Aedes albopictus (Asian tiger mosquito) population. Researchers genotyped 2,669 mosquitoes trapped across Wake County, North Carolina from 2016 to 2024, using an allele-specific PCR melt-curve assay for the F1534S sodium-channel mutation and a Wright-Fisher approximate Bayesian model to estimate the strength of selection. This is a resistance-monitoring study, not a repellent efficacy trial, so it carries no protection-time measurement.
Key findings
Knockdown resistance to pyrethroids emerged and spread strikingly fast. The F1534S kdr allele was undetectable in 2016, first appeared in 2018 in a single central neighborhood, and by 2023 had spread across the entire sampling region, with resistant genotypes present at every long-term site by 2022. The resistance allele frequency peaked at 0.36 in 2023, meaning more than a third of the relevant gene copies in the local population carried the resistant version, and the model indicated strong genetic selection. The mutation blunts pyrethroids specifically, the class behind most consumer yard foggers, mosquito-barrier sprays, coils, and permethrin-treated clothing. It does not affect how skin repellents such as DEET or picaridin work, since those repel by smell and contact rather than by the nerve-channel mechanism pyrethroids attack.
Limitations
The work was carried out entirely within one county (Wake County, NC), so the pace of spread may not generalize elsewhere. It tracked a single mutation (F1534S) as a marker of resistance rather than the full resistance picture, and it did not directly measure how much insecticide residents or mosquito-control companies actually applied, so the link between uncoordinated residential spraying and the rise in resistance is an educated inference, not proven causation. The endpoint is allele frequency in wild mosquitoes, not a measured change in any product's real-world protection, and it concerns pyrethroid area treatments rather than topical skin repellents.