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Background <p>Pyrethroid resistance in <i>Anopheles gambiae</i> sensu lato threatens the efficacy of long-lasting insecticidal nets (LLINs) in Benin. District-level resistance data and evaluations of next-generation insecticides are needed to inform insecticide resistance management (IRM).</p> Methods <p>We assessed insecticide susceptibility in <i>An. gambiae</i> s.l. populations from three southern Beninese districts (Porto-Novo, Akpro-Missérété, Lokossa) via WHO tube bioassays with pyrethroids (deltamethrin, permethrin, alpha-cypermethrin), pirimiphos-methyl, clothianidin, and chlorfenapyr. Molecular species identification and genotyping of the kdr L995F and Ace-1R G119S mutations were performed via allele-specific PCR.</p> Results <p>Confirmed pyrethroid resistance was recorded at all sites, with permethrin mortality as low as 17.1% (95% CI 10.6–26.2%) in Porto-Novo. The kdr L995F allele was detected at near-fixation frequencies ranging from 82 to 93% across both <i>An. coluzzii</i> and <i>An. gambiae</i> s.s. Ace-1R G119S remained rare (3–7%), which is consistent with its retained susceptibility to pirimiphos-methyl. The species composition ranged from exclusive to <i>An. coluzzii</i> in Porto-Novo to near-equal distribution in Lokossa. Clothianidin was associated with ≥ 99% cumulative mortality by day 7, and chlorfenapyr was associated with ≥ 98.8% cumulative mortality within 24–48&#xa0;h across all populations.</p> Conclusions <p>Pyrethroid resistance is entrenched in southern Benin, driven by the near-fixation of kdr L995F along an urbanization gradient. The fully preserved efficacy of clothianidin and chlorfenapyr against these resistant populations supports the urgent scale-up of next-generation LLINs as a core IRM strategy in this high-burden region.</p>

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Widespread pyrethroid resistance and high kdr L995F allele frequencies in Anopheles gambiae sensu lato populations from Southern Benin, West Africa

  • 期刊论文

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  • 发表日期：

    2026年4月18日

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  • Minassou Juvénal Ahouandjinou,
  • Steve Zinsou Hougbe,
  • Zul-kifl Affolabi,
  • Aboubakar Sidick,
  • Koffi Djigbodi Koumodji,
  • Arthur Sovi,
  • Linda Towakinou,
  • Zoulkifilou Sare Dabou,
  • Mahuna Pierre Boko,
  • Kayode Moudjadidou Oyeniran,
  • Olivier Oussou,
  • Haziz A. Sina Orou,
  • Lamine Baba-Moussa,
  • Martin Akogbeto,
  • Razaki A. Ossé

摘要

Background

Pyrethroid resistance in Anopheles gambiae sensu lato threatens the efficacy of long-lasting insecticidal nets (LLINs) in Benin. District-level resistance data and evaluations of next-generation insecticides are needed to inform insecticide resistance management (IRM).

Methods

We assessed insecticide susceptibility in An. gambiae s.l. populations from three southern Beninese districts (Porto-Novo, Akpro-Missérété, Lokossa) via WHO tube bioassays with pyrethroids (deltamethrin, permethrin, alpha-cypermethrin), pirimiphos-methyl, clothianidin, and chlorfenapyr. Molecular species identification and genotyping of the kdr L995F and Ace-1R G119S mutations were performed via allele-specific PCR.

Results

Confirmed pyrethroid resistance was recorded at all sites, with permethrin mortality as low as 17.1% (95% CI 10.6–26.2%) in Porto-Novo. The kdr L995F allele was detected at near-fixation frequencies ranging from 82 to 93% across both An. coluzzii and An. gambiae s.s. Ace-1R G119S remained rare (3–7%), which is consistent with its retained susceptibility to pirimiphos-methyl. The species composition ranged from exclusive to An. coluzzii in Porto-Novo to near-equal distribution in Lokossa. Clothianidin was associated with ≥ 99% cumulative mortality by day 7, and chlorfenapyr was associated with ≥ 98.8% cumulative mortality within 24–48 h across all populations.

Conclusions

Pyrethroid resistance is entrenched in southern Benin, driven by the near-fixation of kdr L995F along an urbanization gradient. The fully preserved efficacy of clothianidin and chlorfenapyr against these resistant populations supports the urgent scale-up of next-generation LLINs as a core IRM strategy in this high-burden region.