Pyrethroid resistance mechanisms in the major malaria vector species complex

Pyrethroids remain the most important class of insecticides for controlling malaria mosquitoes. Resistance to pyrethroids in the major African malaria vector Anopheles gambiae was detected soon after the introduction of this insecticide class in the 1970s but the strength, and distribution, of this resistance has greatly accelerated in the 21st century. In this review we summarise the current understanding of the mechanisms underpinning this resistance, including new discoveries on the genetic basis of established mechanisms such as changes in the neuronal target site of pyrethroids, and latest understandings on less well characterized mechanisms such as insecticide sequestration. Many gaps remain in our understanding of the genetic pathways controlling these resistance associated genes, and for many, the causal resistance mutations remain elusive; this is a key obstacle in the development of informative panels of genetic markers that would aid in the monitoring and management of insecticide resistance in malaria vectors.