Development of an Insecticide-Free Trapping Bednet to Control Mosquitoes and Manage Resistance in Malaria Vector Control: A New Way of Thinking.

Chouaibou S Mouhamadou,Charles S Apperson,Kun Luan,R Michael Roe,Andre J West,Behi K Fodjo,Marian G Mccord

doi:10.3390/insects11110732

Chouaibou S Mouhamadou, Charles S Apperson + Show 5 more

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https://doi.org/10.3390/insects11110732

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Abstract

Simple SummaryInsecticide resistance in mosquitoes reduces the effectiveness of malaria control interventions and has reversed the gains made in reducing malaria morbidity. Hence, new strategies are needed to mitigate the spread of resistance, preserve the efficacy of available insecticides, and restore the effectiveness of control. To combat resistance to insecticides in malaria mosquitoes, WHO recommends using long-lasting insecticide-impregnated mosquito bednets (LLINs) as well as the synergist piperonyl-butoxide (PBO). PBO enhances the insecticidal effect of the treated bednet. Unfortunately, decreases in performance of PBO-LLINs are now reported in some regions of Africa where mosquitoes are resistant to insecticides. Our objective was to develop an insecticide-free, mechanical solution that kills mosquitoes regardless of their insecticide resistance status, ultimately overcoming the problem of insecticide resistance. We designed and developed an insecticide-free mosquito trapping bednet for mass mosquito trapping and killing, the “T-Net”, and we show its efficacy compared to a conventional LLIN in Africa. Mathematical models were also developed to predict T-Net efficacy in individual homes and at the community level.Mosquito-borne malaria kills 429,000 people each year with the problem being acute in sub-Saharan Africa. The successes gained with long-lasting pyrethroid-treated bednets are now in jeopardy because of wide-spread, pyrethroid resistance in mosquitoes. Using crowd modeling theory normalized for standard bednet architecture, we were able to design an attract–trap–kill technology for mosquitoes that does not require insecticides. Using three-dimensional polyester knitting and heat fixation, trap funnels were developed with high capture efficacy with no egression under worst-case laboratory conditions. Field testing in Africa in WHO huts with Gen1-3 T (trap)-Nets validated our model, and as predicted, Gen3 had the highest efficacy with a 4.3-fold greater trap–kill rate with no deterrence or repellency compared to Permanet 2.0, the most common bednet in Africa. A T-Net population model was developed based on field data to predict community-level mosquito control compared to a pyrethroid bednet. This model showed the Gen3 non-insecticidal T-Net under field conditions in Africa against pyrethroid resistant mosquitoes was 12.7-fold more efficacious than single chemical, pyrethroid-treated nets.

Highlights

Malaria is the leading cause of morbidity and mortality in sub-Saharan Africa with 212 million cases annually estimated by the WHO and about 429,000 deaths each year [1]
An estimated 663 million cases of malaria have been averted in sub-Saharan Africa since 2001 as a result of the scale-up of malaria control interventions; 69% of these reduced cases were a direct result of the use of long-lasting insecticide-impregnated mosquito bednets (LLINs) [3]
Proof of concept has demonstrated that a non-insecticidal bednet that kills mosquitoes by mechanical methods, in this case trapping, can be an efficacious “new way of thinking” vastly different from the accepted standard of using bednets treated with insecticides to prevent mosquito biting and to kill mosquitoes in Africa and other places

Summary

Introduction

Malaria is the leading cause of morbidity and mortality in sub-Saharan Africa with 212 million cases annually estimated by the WHO and about 429,000 deaths each year [1]. An estimated 663 million cases of malaria have been averted in sub-Saharan Africa since 2001 as a result of the scale-up of malaria control interventions; 69% of these reduced cases were a direct result of the use of LLINs [3]. Mosquitoes have, in recent years, become resistant to insecticides including the pyrethroids, the only chemistry approved for bednets [4,5,6]. This resistance is threatening the efficacy of chemical-based, vector control [7,8,9]. There is an urgent need to develop new strategies to mitigate this problem

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