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Acetylcholinesterase (Ace-1) target site mutation 119S is strongly diagnostic of carbamate and organophosphate resistance in Anopheles gambiae s.s. and Anopheles coluzzii across southern Ghana.

Essandoh, John, Yawson, Alexander E and Weetman, David ORCID: (2013) 'Acetylcholinesterase (Ace-1) target site mutation 119S is strongly diagnostic of carbamate and organophosphate resistance in Anopheles gambiae s.s. and Anopheles coluzzii across southern Ghana.'. Malaria Journal, Vol 12, Issue 1, e404.

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With high DDT resistance present throughout much of West Africa, carbamates and organophosphates are increasingly important alternatives to pyrethroids for indoor residual spraying (IRS). Though less widespread, resistance to both of these alternative insecticide classes has also been documented within the Anopheles gambiae species pair (formerly the M and S molecular forms) in West Africa. To manage insecticide efficacy, it is important to predict how and where resistance is likely to occur and spread, which could be aided by using molecular diagnostics with high predictive value.


Anopheles coluzzii and An. gambiae s.s. were collected from 18 sites throughout southern Ghana and bioassayed with bendiocarb, the most commonly applied carbamate, and an organophosphate, fenitrothion. The Ace-1 target site substitution G119S was genotyped by qPCR.


Fenitrothion induced higher mortality than bendiocarb, though phenotypes correlated strongly across populations. Ace-1 119S was found at much higher frequency in An. gambiae s.s than An. coluzzii, exceeding 90 % in a population from Greater Accra, the highest frequency reported to date. Ace-1 G119S was very strongly associated with resistance to both insecticides, providing high predictive power for diagnosis, though with some evidence for a differential effect between molecular forms for bendiocarb. Sequencing of the gene revealed a lack of variation in resistant alleles precluding determination of origin, but Ace-1 copy number variation was detected for the first time in Ghana.


The results validate the utility of G119S as a useful diagnostic of organophosphate and carbamate resistance within and among populations, whilst highlighting the potential for an aggregate nature of Ace-1 genotypes, which may comprise both single-copy and duplicated genes. Further work is now required to determine the distribution and resistance-association of Ace-1 duplication.

Item Type: Article
Subjects: QU Biochemistry > Genetics > QU 470 Genetic structures
QX Parasitology > Insects. Other Parasites > QX 510 Mosquitoes
QX Parasitology > Insects. Other Parasites > QX 600 Insect control. Tick control
WA Public Health > Preventive Medicine > WA 240 Disinfection. Disinfestation. Pesticides (including diseases caused by)
WA Public Health > Health Problems of Special Population Groups > WA 395 Health in developing countries
WC Communicable Diseases > Tropical and Parasitic Diseases > WC 750 Malaria
Faculty: Department: Biological Sciences > Vector Biology Department
Digital Object Identifer (DOI):
Depositing User: Samantha Sheldrake
Date Deposited: 28 Nov 2013 11:37
Last Modified: 17 Aug 2022 08:56


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