The ability of Anopheles funestus and A. arabiensis to penetrate LLINs and its effect on their mortality

Abstract

<ns4:p> <ns4:bold>Background:</ns4:bold> Variation in mosquito body size and the ability to penetrate long-lasting insecticide-treated nets (LLINs) remains unknown. This study evaluated the ability of <ns4:italic>Anopheles funestus</ns4:italic> and <ns4:italic>A. arabiensis</ns4:italic> to penetrate commercially available treated and untreated bednets and how this behaviour affects mosquito mortality. </ns4:p> <ns4:p> <ns4:bold>Methods:</ns4:bold> Three types of LLINs; DawaPlus 2.0, PermaNet 2.0, Olyset 2.0, and untreated (Safi Net) were tested inside a semi-field system. One hundred 3–5-day-old female <ns4:italic>A. funestus</ns4:italic> and <ns4:italic>A. arabiensis</ns4:italic> were released in a chamber with a sleeping adult volunteer under a treated or untreated bednet. Mosquitoes that penetrated inside the nets were collected every two hours using a mouth aspirator. Live mosquitoes were put in paper cups, fed on glucose <ns4:italic>ad libitum</ns4:italic> and their mortality rate was monitored for 48 h. </ns4:p> <ns4:p> <ns4:bold>Results:</ns4:bold> The ability of <ns4:italic>A. funestus</ns4:italic> to penetrate treated and untreated bednets was significantly higher than for <ns4:italic>A. arabiensis</ns4:italic> for all three LLIN net types ( <ns4:italic>P</ns4:italic> &lt;0.001). For both species the penetration rate was higher for untreated bednets than treated ones except for the Olyset net. Of all mosquitoes that penetrated the net, regardless of the species, &gt;90% successfully blood-fed on the sleeping volunteer. Compared to <ns4:italic>A. arabiensis</ns4:italic> , significant mortality was recorded for <ns4:italic>A. funestus</ns4:italic> that were caught inside Olyset nets within 48 hrs of monitoring ( <ns4:italic>P</ns4:italic> &lt;0.001). </ns4:p> <ns4:p> <ns4:bold>Conclusions:</ns4:bold> </ns4:p> <ns4:p> These findings demonstrate the ability of <ns4:italic>A. funestus</ns4:italic> and <ns4:italic>A. arabiensis</ns4:italic> mosquitoes to penetrate the human-occupied treated and untreated bednets. Despite this ability, mosquitoes that penetrated the bednet succumbed to death within two days. </ns4:p>

Topics & Concepts