Efficacy of pyriproxyfen-pyrethroid long-lasting insecticidal nets (LLINs) and chlorfenapyr-pyrethroid LLINs on mosquito feeding and resting behaviour in Benin, West Africa

Abstract

Innovative mosquito nets combining pyrethroids with Pyriproxyfen or Chlorfenapyr significantly reduced Anopheles densities in Benin, but their impact on the feeding/resting behaviour of pyrethroid-resistant mosquitoes remains unstudied. Our study assessed the impact of pyriproxyfen-pyrethroid (Pyr-PPF) and chlorfenapyr-pyrethroid (Pyr-CFP) LLINs on the feeding/resting behaviour of pyrethroid-resistant mosquitoes in Benin, aiming to inform future mosquito control strategies amidst rising insecticide resistance. The study was conducted in the communes of Covè, Zangnanado, and Ouinhi in southern Benin, with 60 clusters randomly assigned to three treatment groups: Pyr-CFP LLINs, Pyr-PPF LLINs, and Pyr only LLINs as a control. Mosquitoes were collected using the Pyrethrum Spray Catch (PSC) method, their blood meals analysed using the Sandwich ELISA method, and the data analysed using a mixed-effect generalized linear model. A total of 6,925 mosquitoes were collected during the study, with Anopheles spp. (38%), Culex spp. (30.6%), and Mansonia spp. (28.9%). being the most common genera. Blood feeding rates (BFR) were high for Anopheles spp. (72.1% to 86.5%), with no significant differences between study arms after two years. Significant reductions in BFR for Culex spp. (BFR=15.0; 95%CI: 11.8-18.9) and Mansonia spp. (27.0; 23.1-31.3) were observed in the Pyr-PPF LLIN arm compared to Pyr only LLINs ([26.3; 22.2-30.8] and [41.9; 37.3-46.6] respectively). Indoor resting densities (IRD) of Anopheles spp. were significantly reduced in the Pyr-PPF LLIN and Pyr-CFP LLIN arms compared to the control arm (p