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Background The movement of malaria vectors into new areas is a growing concern in the efforts to control malaria. The recent report of Anopheles stephensi in eastern Ethiopia has raised the necessity to understand the insecticide resistance status of the vector in the region to better inform vector-based interventions. The aim of this study was to evaluate insecticide resistance in An. stephensi in eastern Ethiopia using two approaches: 1) World Health Organization (WHO) bioassay tests in An. stephensi; and 2) genetic analysis of insecticide resistance genes in An. stephensi in eastern Ethiopia.
Methods Mosquito larvae and pupae were collected from Kebri Dehar. Insecticide susceptibility of An. stephensi was tested withmalathion 5%, bendiocarb 0.1%, propoxur 0.1%, deltamethrin 0.05%, permethrin 0.75%, Pirimiphos-methyl 0.25% and DDT 4%, according to WHO standard protocols. In this study, the knockdown resistance locus (kdr) in the voltage gated sodium channel (vgsc) and ace1R locus in the acetylcholinesterase gene (ace-1) were analysed in An. stephensi.
Results All An. stephensi samples were resistant to carbamates, with mortality rates of 23% and 21% for bendiocarb and propoxur, respectively. Adult An. stephensi was also resistant to pyrethroid insecticides with mortality rates 67% for deltamethrin and 53% for permethrin. Resistance to DDT and malathion was detected in An. stephensi with mortality rates of 32% as well as An. stephensi was resistance to pirimiphos-methyl with mortality rates 14%. Analysis of the insecticide resistance loci revealed the absence of kdr L1014F and L1014S mutations and the ace1R G119S mutation.
Conclusion Overall, these findings support that An. stephensi is resistant to several classes of insecticides, most notably pyrethroids. However, the absence of the kdr L1014 gene may suggest non-target site resistance mechanisms. Continuous insecticide resistance monitoring should be carried out in the region to confirm the documented resistance and exploring mechanisms conferring resistance in An. stephensi in Ethiopia.
Keywords
Malaria, Anopheles stephensi, Insecticide resistance, Kebri Dehar, Somali Region
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View the published article at Malaria Journal.
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Editorial decision: Accept
On 02 May, 2020
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Review #1 received
Received 19 Apr, 2020
Editorial decision: Minor Revision
On 19 Apr, 2020
Reviewer #1 agreed
On 03 Apr, 2020
Reviewers invited
Invitations sent on 10 Feb, 2020
Editor assigned
On 07 Feb, 2020
Submission checks complete
On 06 Feb, 2020
Editor invited
On 06 Feb, 2020
No comments provided
Editorial decision: Major Revision
On 08 Jan, 2020
Review #2 received
Received 31 Dec, 2019
Review #1 received
Received 20 Dec, 2019
Reviewers invited
Invitations sent on 29 Nov, 2019
Reviewer #1 agreed
On 29 Nov, 2019
Reviewer #2 agreed
On 29 Nov, 2019
Editor assigned
On 28 Nov, 2019
First submitted
On 27 Nov, 2019
Submission checks complete
On 27 Nov, 2019
Editor invited
On 27 Nov, 2019
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Subject Areas
Infectious Diseases
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See the published version of this preprint at Malaria Journal.
This is a preprint, a preliminary version of a manuscript that has not completed peer review at a journal. Research Square does not conduct peer review prior to posting preprints. The posting of a preprint on this server should not be interpreted as an endorsement of its validity or suitability for dissemination as established information or for guiding clinical practice.
Learn more about In Review
Research
Badges
Prescreen
This manuscript passed our Prescreen assessment
Complete author information
Appropriate declaration statements
Potential risks to human health
Prescreen
Peer Review Timeline
CURRENT STATUS: Published
View the published article at Malaria Journal.
Version 3
Posted 15 May, 2020
No community comments so far
Editor assigned
On 02 May, 2020
Editorial decision: Accept
On 02 May, 2020
Submission checks complete
On 01 May, 2020
Editor invited
On 01 May, 2020
No comments provided
Review #1 received
Received 19 Apr, 2020
Editorial decision: Minor Revision
On 19 Apr, 2020
Reviewer #1 agreed
On 03 Apr, 2020
Reviewers invited
Invitations sent on 10 Feb, 2020
Editor assigned
On 07 Feb, 2020
Submission checks complete
On 06 Feb, 2020
Editor invited
On 06 Feb, 2020
No comments provided
Editorial decision: Major Revision
On 08 Jan, 2020
Review #2 received
Received 31 Dec, 2019
Review #1 received
Received 20 Dec, 2019
Reviewers invited
Invitations sent on 29 Nov, 2019
Reviewer #1 agreed
On 29 Nov, 2019
Reviewer #2 agreed
On 29 Nov, 2019
Editor assigned
On 28 Nov, 2019
First submitted
On 27 Nov, 2019
Submission checks complete
On 27 Nov, 2019
Editor invited
On 27 Nov, 2019
Metrics
Comments: 0
PDF Downloads: ...
HTML Views: ...
Subject Areas
Infectious Diseases
License:
This work is licensed under a CC BY 4.0 License. Read Full License
View the published article at Malaria Journal.
Background The movement of malaria vectors into new areas is a growing concern in the efforts to control malaria. The recent report of Anopheles stephensi in eastern Ethiopia has raised the necessity to understand the insecticide resistance status of the vector in the region to better inform vector-based interventions. The aim of this study was to evaluate insecticide resistance in An. stephensi in eastern Ethiopia using two approaches: 1) World Health Organization (WHO) bioassay tests in An. stephensi; and 2) genetic analysis of insecticide resistance genes in An. stephensi in eastern Ethiopia.
Methods Mosquito larvae and pupae were collected from Kebri Dehar. Insecticide susceptibility of An. stephensi was tested withmalathion 5%, bendiocarb 0.1%, propoxur 0.1%, deltamethrin 0.05%, permethrin 0.75%, Pirimiphos-methyl 0.25% and DDT 4%, according to WHO standard protocols. In this study, the knockdown resistance locus (kdr) in the voltage gated sodium channel (vgsc) and ace1R locus in the acetylcholinesterase gene (ace-1) were analysed in An. stephensi.
Results All An. stephensi samples were resistant to carbamates, with mortality rates of 23% and 21% for bendiocarb and propoxur, respectively. Adult An. stephensi was also resistant to pyrethroid insecticides with mortality rates 67% for deltamethrin and 53% for permethrin. Resistance to DDT and malathion was detected in An. stephensi with mortality rates of 32% as well as An. stephensi was resistance to pirimiphos-methyl with mortality rates 14%. Analysis of the insecticide resistance loci revealed the absence of kdr L1014F and L1014S mutations and the ace1R G119S mutation.
Conclusion Overall, these findings support that An. stephensi is resistant to several classes of insecticides, most notably pyrethroids. However, the absence of the kdr L1014 gene may suggest non-target site resistance mechanisms. Continuous insecticide resistance monitoring should be carried out in the region to confirm the documented resistance and exploring mechanisms conferring resistance in An. stephensi in Ethiopia.
Figure 1
Figure 2
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