Evaluation of the effectiveness of toxic sugar baits based on ivermectin against pyrethroid-resistant Anopheles funestus s.s. and Anopheles gambiae s.s. in the Sud-Kivu province, Democratic Republic of the Congo

Abstract

Background: Toxic sugar baits (TSBs) are oral toxins used against vectors. However, the effectiveness of this vector control tool remains to be demonstrated. The objective of this study was to evaluate in the laboratory the effectiveness of TSBs based on ivermectin against pyrethroid-resistant Anopheles funestus s.s. and Anopheles gambiae s.s. in the Democratic Republic of the Congo. Method: Mosquito larvae were collected in the village of Tchonka in the Democratic Republic of the Congo and reared to adult under standard insectarium conditions. Adult female mosquitoes were kept in cages and fed with a 10 % sugar solution containing ivermectin at different concentrations. The effectiveness of ivermectin was evaluated in terms of induced mosquito mortality after 72 hours.
Results:The study showed that: (i) TSBs with 0.005 % ivermectin induce 100 % mortality in pyrethroid-resistant Anopheles funestus s.s. and Anopheles gambiae s.s. within 72 hours, (ii) mosquitoes do not exhibit the ability to recognize ivermectin-based TSBs to avoid them and feed on other sugar sources, (iii) ivermectin-based TSBs should be replenished weekly in the field. Conclusion : TSBs could serve as a complement or even an alternative to insecticide-treated materials, which are the standard for malaria prevention.