Biology subjects

Gbegbo, M.

Publications and source records attributed to Gbegbo, M..

3 recordsLinked to original sources

bioRxiv2023

PermaNet(R) Dual, a new deltamethrin-chlorfenapyr mixture net, shows improved efficacy against pyrethroid-resistant Anopheles gambiae sensu lato in southern Benin

Pyrethroid-chlorfenapyr nets have demonstrated improved entomological and epidemiological impact in trials across Africa. This is driving increased demand for this novel net class in malaria endemic countries. PermaNet(R) Dual is a new deltamethrin-chlorfenapyr net developed by Vestergaard Sarl to provide more options to malaria control programmes. We performed an experimental hut trial to evaluate the efficacy of PermaNet(R) Dual against wild, free-flying pyrethroid-resistant Anopheles gambiae sensu lato in Cove, Benin. PermaNet(R) Dual induced superior levels of mosquito mortality compared to a pyrethroid-only net and a pyrethroid-piperonyl butoxide net both when unwashed (77% with PermaNet(R) Dual vs. 23% with PermaNet(R) 2.0 and 56% with PermaNet(R) 3.0, p<0.001) and after 20 standardised washes (75% with PermaNet(R) Dual vs. 14% with PermaNet(R) 2.0 and 30% with PermaNet(R) 3.0, p<0.001). Using a provisional non-inferiority margin defined by the World Health Organisation, PermaNet(R) Dual was also non-inferior to a pyrethroid-chlorfenapyr net that has demonstrated improved public health value (Interceptor(R) G2), for vector mortality (79% vs. 76%, OR=0.854, 95% CIs: 0.703-1.038) but not for blood-feeding protection (35% vs. 26%, OR=1.445, 95% CIs: 1.203-1.735). PermaNet(R) Dual presents an additional option of this highly effective net class for improved control of malaria transmitted by pyrethroid-resistant mosquitoes.

zoology↗

bioRxiv2022

VECTRON™ T500, a new broflanilide insecticide for indoor residual spraying, provides prolonged control of pyrethroid-resistant malaria vectors

BackgroundBroflanilide is a newly discovered insecticide with a novel mode of action targeting insect {gamma}-aminobutyric acid receptors. The efficacy of VECTRON T500, a wettable powder formulation of broflanilide, was assessed for IRS against wild pyrethroid-resistant malaria vectors in experimental huts in Benin. MethodsVECTRON T500 was evaluated at 100 mg/m{superscript 2} in mud and cement-walled experimental huts against wild pyrethroid-resistant Anopheles gambiae sensu lato (s.l.) in Cove, southern Benin, over 18 months. A direct comparison was made with Actellic(R) 300CS, a WHO-recommended micro-encapsulated formulation of pirimiphos-methyl, applied at 1000 mg/m{superscript 2}. The vector population at Cove was investigated for susceptibility to broflanilide and other classes of insecticides used for vector control. Monthly wall cone bioassays were performed to assess the residual efficacy of VECTRON T500 using insecticide susceptible An. gambiae Kisumu and pyrethroid-resistant An. gambiae s.l. Cove strains. The study complied with OECD principles of good laboratory practice. ResultsThe vector population at Cove was resistant to pyrethroids and organochlorines but susceptible to broflanilide and pirimiphos-methyl. A total of 23,171 free-flying wild pyrethroid-resistant female An. gambiae s.l. were collected in the experimental huts over 12 months. VECTRON T500 induced 56%-60% mortality in wild vector mosquitoes in both cement and mud-walled huts. Mortality with VECTRON T500 was 62%-73% in the first three months and remained >50% for 9 months on both substrate-types. By comparison, mortality with Actellic(R) 300CS was very high in the first three months (72%-95%) but declined sharply to <40% after 4 months. Using a non-inferiority margin defined by the World Health Organization, overall mortality achieved with VECTRON T500 was non-inferior to that observed in huts treated with Actellic(R) 300CS with both cement and mud wall substrates. Monthly in situ wall cone bioassay mortality with VECTRON T500 also remained over 80 % for 18 months but dropped below 80% with Actellic(R) 300CS at 6-7 months post spraying. ConclusionVECTRON T500 shows potential to provide substantial and prolonged control of malaria transmitted by pyrethroid-resistant mosquito vectors when applied for IRS. Its addition to the current list of WHO-approved IRS insecticides will provide a suitable option to facilitate rotation of IRS products with different modes of action.

zoology↗

bioRxiv2021

Can pyrethroid-piperonyl butoxide (PBO) nets reduce the efficacy of indoor residual spraying with pirimiphos-methyl against pyrethroid-resistant malaria vectors?

As the uptake of pyrethroid-PBO ITNs increases, their combination with IRS insecticides could become an operational reality in many malaria-endemic communities. Pirimiphos-methyl is a pro-insecticide requiring activation by mosquito cytochrome P450 enzymes to induce toxicity while PBO blocks activation of these enzymes in pyrethroid-resistant vector mosquitoes. PBO may thus antagonise the toxicity of pirimiphos-methyl IRS when combined with pyrethroid-PBO ITNs. The impact of combining two major brands of pyrethroid-PBO ITNs (Olyset(R) Plus, PermaNet(R) 3.0) with pirimiphos-methyl IRS (Actellic(R) 300CS) was evaluated against pyrethroid-resistant Anopheles gambiae sl in two parallel experimental hut trials in southern Benin in comparison to bendiocarb IRS and each intervention alone. The wild vector population was resistant to pyrethroids but susceptible to pirimiphos-methyl and bendiocarb. PBO pre-exposure partially restored deltamethrin toxicity but not permethrin. Mosquito mortality in experimental huts was significantly improved in the combinations of bendiocarb IRS with Olyset(R) Plus (33%) and PermaNet(R) 3.0 (38%) compared to bendiocarb IRS alone (14-16%, p<0.001), demonstrating an additive effect. Conversely, mortality was significantly reduced in the combinations of pirimiphos-methyl IRS with Olyset(R) Plus (59%) and PermaNet(R) 3.0 (55%) compared to pirimiphos-methyl IRS alone (77-78%, p<0.001), demonstrating an antagonistic effect. Combining pirimiphos-methyl IRS with the pyrethroid-PBO ITNs provided significantly improved mosquito mortality (55-59%) compared to the pyrethroid-PBO ITNs alone (22-26%) and improved blood-feeding inhibition relative to the IRS alone. This study provided evidence of an antagonistic effect when pyrethroid-PBO ITNs were combined with pirimiphos-methyl IRS in the same household resulting in lower levels of vector mosquito mortality compared to the IRS alone. Pirimiphos-methyl IRS also showed potential to significantly enhance malaria control when deployed to complement pyrethroid-PBO ITNs in an area where PBO fails to fully restore susceptibility to pyrethroids.

zoology↗