Multiple Resistance Mechanisms to Pyrethroids Insecticides in Anopheles gambiae sensu lato Population From Mali, West Africa

Abstract

Background Insecticide-based vector control is responsible for reducing malaria mortality and morbidity. Its success depends on a better knowledge of the vector, its distribution, and resistance status to the insecticides used. In this paper, we assessed Anopheles gambiae sensu lato (A gambiae s.l.) population resistance to pyrethroids in different ecological settings. Methods The World Health Organization standard bioassay test was used to assess F0A gambiae s.l. susceptibility to pyrethroids. Biochemical Synergist assays were conducted with piperonyl butoxide (PBO), S,S,S-tributyl phosphotritioate, and diethyl maleate. L1014F, L1014S, and N1575Y knockdown resistance (kdr) mutations were investigated using TaqMan genotyping. Results Anopheles gambiae sensu lato was composed of Anopheles arabienisis, Anopheles coluzzii, and A gambiae in all study sites. Anopheles gambiae sensu lato showed a strong phenotypic resistance to deltamethrin and permethrin in all sites (13% to 41% mortality). In many sites, pre-exposure to synergists partially improved the mortality rate suggesting the presence of detoxifying enzymes. The 3 kdr (L1014F, L1014S, and N1575Y) mutations were found, with a predominance of L1014F, in all species. Conclusions Multiple resistance mechanisms to pyrethroids were observed in A gambiae s.l. in Mali. The PBO provided a better partial restoration of susceptibility to pyrethroids, suggesting that the efficacy of long-lasting insecticidal nets may be improved with PBO.

Evolution of the Pyrethroids Target-Site Resistance Mechanisms in Senegal: Early Stage of the Vgsc-1014F and Vgsc-1014S Allelic Frequencies Shift

“…It could have been introduced to Senegal by migration, as previously suggested in Burkina Faso [ 35 ]. The presence of the Vgsc-1014S mutation in the current study is consistent with several reports from West African countries such as Benin [ 13 ], Burkina Faso [ 38 ], Côte d’Ivoire [ 39 ], Mali [ 40 ], and The Gambia [ 36 ].…”

Emerging mosquito resistance to piperonyl butoxide-synergized pyrethroid insecticide and its mechanism

“…The phenomena of the insecticide-resistant mosquitoes’ insensitivity to PBO exposure or PBO-LLIN have also been reported for Aedes and Anopheles mosquitoes from different countries [28,31,36–40]. For example, in Marcombe and colleagues’ study in Laos, for highly permethrin-resistant Ae.…”

“…These results suggest that highly insecticide-resistant mosquitoes may tolerant PBO exposure regardless of species. In nearly all cases, multiple resistance mechanisms have been reported, including presence of different detoxifying enzymes and different kdr mutations [37–40].…”

“…gambiae s.l. study in Mali, Keita and colleagues’ found that in several places PBO exposure could only increase mosquito mortalities to pyrethroid insecticides from 24-41% to 34-45% [40]. In Riveron et al study of An.…”

“…Although increased enzyme activity and expression in P450 CYP genes have been well recognized as the major mechanisms for pyrethroid resistance [8,40,42,43,49,50], it is unclear why the effect of PBO exposure is limited in reducing resistance levels. One possibility is the existence of multiple mechanisms of resistance.…”