Longitudinal Survey of Knockdown Resistance to Pyrethroid (Kdr) in Mali, West Africa, and Evidence of Its Emergence in the Bamako Form of Anopheles Gambiae S.S.

Abstract

Studies aimed at monitoring the spread of knockdown resistance to pyrethroids (kdr) in time and space are particularly useful for detecting barriers to gene flow among the chromosomal and molecular forms of Anopheles gambiae. We used a recently developed polymerase chain reaction assay to estimate changes in kdr frequency that occurred in several mixed-form populations from Mali, West Africa, in the past decade. We found that the kdr allele significantly increased in frequency in most populations but was still absent from the M molecular form. Importantly, within the S molecular form, kdr was detected for the first time in the Bamako chromosomal form. These results provide important insights on the patterns of spread and emergence of pyrethroid knockdown resistance in West Africa.

Adaptive introgression in an African malaria mosquito coincident with the increased usage of insecticide-treated bed nets

“…Selection for L1014F had been strong in the A. gambiae population in the Sidarebougou region for decades, likely related to widespread pyrethroid use in cotton agriculture in this region (13,14). Likewise, before L1014F was present in A. gambiae, although at a lower frequency, in Selinkenyi, where intermediate usage of pyrethroid on crops has been reported (14).…”

“…Likewise, before L1014F was present in A. gambiae, although at a lower frequency, in Selinkenyi, where intermediate usage of pyrethroid on crops has been reported (14). In 2005, the Malian Ministry of Health began providing free ITNs to children (26), and the President's Malaria Initiative began operations in Mali shortly thereafter, providing 369,800 ITNs in 2007 (24).…”

“…This study provides a rare example of adaptive introgression in an animal species and elucidates the dynamics of how insecticide resistance evolved in A. coluzzii. (14), but was found to be absent in sympatric A. coluzzii populations (16)(17)(18). The first report of L1014F in A. coluzzii came in 2000 from samples collected in southern Benin.…”

“…The L1014F SNP is thought to have arisen in West African A. gambiae populations (12) and confers target site resistance to dichlorodiphenyltrichloroethane (DDT) and pyrethroid insecticides (11,13). Recent and intense pyrethroid-based control programs are thought to have strongly selected for L1014F in A. gambiae (14,15). L1014F has been present in some A. gambiae populations for at least 20 y…”

Flaws In Housing Designs That Aid Malaria Vector Invasion of Human Habitat And Malaria Transmission –A Review.

“…These again are all losing adequate efficacy [5,6] . The emergence and spread of insecticide resistance worldwide is a major threat to malaria control [7][8][9][10][11] . One of the consequences of the massive scale up of vector control interventions is an increased selective pressure for resistance of malaria vector mosquitoes.…”