Horizontal Life Table Characteristics of the Malaria Vectors Anopheles Culicifacies and Anopheles Stephensi (Diptera: Culicidae)1

Abstract 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.

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Evaluation of Hexane Extract of Tuber of Root ofCyperus rotundusLinn (Cyperaceae) for Repellency against Mosquito Vectors

Journal of Parasitology Research ◽

10.1155/2009/908085 ◽

2009 ◽

Vol 2009 ◽

pp. 1-5 ◽

Cited By ~ 3

Author(s):

S. P. Singh ◽

K. Raghavendra ◽

A. P. Dash

Keyword(s):

Culex Quinquefasciatus ◽

Low Dose ◽

Anopheles Stephensi ◽

Hexane Extract ◽

Cyperus Rotundus ◽

Protective Measure ◽

Mosquito Vector ◽

Anopheles Culicifacies ◽

Clear Dose Response ◽

Tuber Extract

Hexane extract of tuber of plantCyperus rotundus(Cyperaceae) was screened under laboratory conditions for repellent activity against mosquito vectorAnopheles culicifaciesGiles species A (Diptera: Culicidae),Anopheles stephensiListon (Diptera: Culicidae), andCulex quinquefasciatusSay (Diptera: Culicidae). TheCyperus rotundustuber extract was used to determine their effect on mosquito vector, and comparison with the DEET (NN Diethyl 1-3 methyl Benzamide, formerly known as diethyl 1-m-toluamide). The tuber extracts showed more effective at all the dose. Result obtained from the laboratory experiment showed that the tuber extracts are more effective for repellency of allthe mosquito vector even at low dose. Clear dose response relationships were established with the highest dose of 10% tuber extract evoking 100% repellency. Percent protection obtained againstAn. culicifaciesGiles species A 100% repellency in 4 hours, 6 hours,An. stephensi100% repellency in 6 hours andCx. quinquefasciatuswas 100% repellency in 6 hours at the 10% concentration. Against DEET- 2.5%An. culicifaciesA 100% repellency in 1 hour, 2 hours, 6 hours, An.stephensihave shown 100% repellency in 6 hours, andCulex quinquefasciatushave shown 100% repellency in 1 hour, 2 hours, 6 hours. The consolidated data of the repellency observed in different species is given and it is evident that the over all repellency rates varied between 80 and 100% for different repellents concentrations (2.5%, 5%, and 10%). The extract can be applied as an effective personal protective measure against mosquito bites.

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Insecticide Resistance in Anopheles stephensi in Somali Region, Eastern Ethiopia

10.21203/rs.2.18020/v2 ◽

2020 ◽

Cited By ~ 1

Author(s):

Solomon Yared ◽

Araya Gebressielasie ◽

Lambodhar Damodaran ◽

Victoria Bonnell ◽

Karen Lopez ◽

...

Keyword(s):

Insecticide Resistance ◽

Anopheles Stephensi ◽

Mortality Rates ◽

Resistance Mechanisms ◽

World Health ◽

Malaria Vectors ◽

Eastern Ethiopia ◽

Pyrethroid Insecticides ◽

Pirimiphos Methyl ◽

Health Organization

Abstract 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 Kebridehar. Insecticide susceptibility of An. stephensi was tested with malathion 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. Results: All An. stephensi samples were resistant to carbamates, with mortality rates 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 voltage gate sodium channel gene (vgsc) revealed the absence of kdr L1014 mutations. 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.

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