Abstract
Widespread resistance to pyrethroids threatens malaria control in Africa. Consequently, several countries switched to carbamates and organophophates insecticides for indoor residual spraying. However, a mutation in the ace-1 gene conferring resistance to these compounds (ace-1R allele), is already present. Furthermore, a duplicated allele (ace-1D) recently appeared; characterizing its selective advantage is mandatory to evaluate the threat. Our data revealed that a unique duplication event, pairing a susceptible and a resistant copy of the ace-1 gene spread through West Africa. Further investigations revealed that, while ace-1D confers less resistance than ace-1R, the high fitness cost associated with ace-1R is almost completely suppressed by the duplication for all traits studied. ace-1 duplication thus represents a permanent heterozygote phenotype, selected, and thus spreading, due to the mosaic nature of mosquito control. It provides malaria mosquito with a new evolutionary path that could hamper resistance management.
Highlights
High mortality of PYR- resistant An. gambiae in Ivory Coast and Benin[22,23,24]
Several similar duplicated alleles have been observed in Cx. pipiens[43,44], where they have been shown to be selected because they reduce the fitness cost associated with the G119S mutation[45,46,47]
This study revealed that ace-1D is expected to spread, threatening the switch to OPs or CXs for malaria mosquito control in countries with PYR-resistant populations
Summary
High mortality of PYR- resistant (kdrR) An. gambiae in Ivory Coast and Benin[22,23,24]. Resistance has been shown to result from overexpression of detoxification enzymes[31,32], highest resistance levels are due to mutation in the target of OPs and CXs, the acetylcholinesterase (AChE1) encoded by the ace-1 gene: a single amino acid substitution of glycine by serine at the position 119 (G119S) resulting in a major conformational change[33] This ace-1R resistant allele arose independently several times in distinct mosquito species[34,35]. A new ace-1 allele has been found in An. gambiae and An. coluzzii in several West African countries (e.g. Ivory Coast and Burkina Faso)[41,42] This allele, named ace-1D, consists in a duplication of the ace-1 gene, associating a susceptible and a resistant copy probably on the same chromosome. This study revealed that ace-1D is expected to spread, threatening the switch to OPs or CXs for malaria mosquito control in countries with PYR-resistant populations
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
