Mosquitocidal effect of ivermectin-treated nettings and sprayed walls on Anopheles gambiae s.s

Abstract

Ivermectin (IVM) has been proposed as a new tool for malaria control as it is toxic on vectors feeding on treated humans or cattle. Nevertheless, IVM may have a direct mosquitocidal effect when applied on bed nets or sprayed walls. The potential for IVM application as a new insecticide for long-lasting insecticidal nets (LLINs) and indoor residual spraying (IRS) was tested in this proof-of-concept study in a laboratory and semi-field environment. Laboratory-reared, insecticide-susceptible Kisumu Anopheles gambiae were exposed to IVM on impregnated netting materials and sprayed plastered- and mud walls using cone bioassays. The results showed a direct mosquitocidal effect of IVM on this mosquito strain as all mosquitoes died by 24 h after exposure to IVM. The effect was slower on the IVM-sprayed walls compared to the treated nettings. Further work to evaluate possibility of IVM as a new insecticide formulation in LLINs and IRS will be required.

Figure 1

Dose-response plot showing mosquitoes’ mortality to increasing concentrations of IVM.

Figure 2

Kaplan Meier survival curves of mosquitoes on IVM-treated surfaces.

Figure 3

K-M survival curves of mosquitoes blood-fed 12 h pre-and post-IVM exposure.