An Experimental Hut Evaluation of PBO-Based and Pyrethroid-Only Nets against the Malaria Vector Anopheles funestus Reveals a Loss of Bed Nets Efficacy Associated with GSTe2 Metabolic Resistance

• Published in: Genes Vol. 11; no. 2; p. 143
• Main Authors: Menze, Benjamin D, Kouamo, Mersimine F, Wondji, Murielle J, Tchapga, Williams, Tchoupo, Micareme, Kusimo, Michael O, Mouhamadou, Chouaibou S, Riveron, Jacob M, Wondji, Charles S
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI 29.01.2020
• Subjects: Animals; Anopheles - drug effects; Anopheles - genetics; Cameroon; Glutathione Transferase - genetics; Insect Proteins - genetics; Insecticide Resistance - drug effects; Insecticide-Treated Bednets - parasitology; Malaria - prevention & control; Malaria - transmission; Mosquito Control; Mosquito Vectors - drug effects; Mosquito Vectors - genetics; Piperonyl Butoxide - pharmacology; Pyrethrins - pharmacology; Cameroon; Anopheles funestus; metabolic resistance; piperonyl butoxide; Long Lasting Insecticidal Nets; glutathione S-transferase; insecticide resistance; malaria
• ISSN: 2073-4425; 2073-4425
• DOI: 10.3390/genes11020143

Growing insecticide resistance in malaria vectors is threatening the effectiveness of insecticide-based interventions, including Long Lasting Insecticidal Nets (LLINs). However, the impact of metabolic resistance on the effectiveness of these tools remains poorly characterized. Using experimental hut trials and genotyping of a glutathione S-transferase resistance marker (L119F- ), we established that GST-mediated resistance is reducing the efficacy of LLINs against . Hut trials performed in Cameroon revealed that Piperonyl butoxide (PBO)-based nets induced a significantly higher mortality against pyrethroid resistant than pyrethroid-only nets. Blood feeding rate and deterrence were significantly higher in all LLINs than control. Genotyping the L119F- mutation revealed that, for permethrin-based nets, 119F- resistant mosquitoes have a greater ability to blood feed than susceptible while the opposite effect is observed for deltamethrin-based nets. For Olyset Plus, a significant association with exophily was observed in resistant mosquitoes (OR = 11.7; < 0.01). Furthermore, -resistant mosquitoes (cone assays) significantly survived with PermaNet 2.0 (OR = 2.1; < 0.01) and PermaNet 3.0 (side) (OR = 30.1; < 0.001) but not for Olyset Plus. This study shows that the efficacy of PBO-based nets (e.g., blood feeding inhibition) against pyrethroid resistant malaria vectors could be impacted by other mechanisms including GST-mediated metabolic resistance not affected by the synergistic action of PBO. Mosaic LLINs incorporating a GST inhibitor (diethyl maleate) could help improve their efficacy in areas of GST-mediated resistance.