Search

Your search keyword '"Romaric B Akoton"' showing total 4 results
Start Over Author "Romaric B Akoton"
4 results on '"Romaric B Akoton"'

1. Putative pleiotropic effects of the knockdown resistance (L1014F) allele on the life-history traits of Anopheles gambiae

Author

Adandé A. Medjigbodo, Luc S. Djogbénou, Oswald Y. Djihinto, Romaric B. Akoton, Emmanuella Abbey, Rosaria M. Kakossou, Eric G. Sonounameto, Esther B. J. Salavi, Laurette Djossou, and Athanase Badolo

Subjects
Kdr R allele, Fitness effects, Life-history traits, Anopheles gambiae, Malaria, Arctic medicine. Tropical medicine, RC955-962, Infectious and parasitic diseases, RC109-216
Abstract

Abstract Background Existing mechanisms of insecticide resistance are known to help the survival of mosquitoes following contact with chemical compounds, even though they could negatively affect the life-history traits of resistant malaria vectors. In West Africa, the knockdown resistance mechanism kdr R (L1014F) is the most common. However, little knowledge is available on its effects on mosquito life-history traits. The fitness effects associated with this knockdown resistance allele in Anopheles gambiae sensu stricto (s.s.) were investigated in an insecticide-free laboratory environment. Methods The life-history traits of Kisumu (susceptible) and KisKdr (kdr resistant) strains of An. gambiae s.s. were compared. Larval survivorship and pupation rate were assessed as well as fecundity and fertility of adult females. Female mosquitoes of both strains were directly blood fed through artificial membrane assays and then the blood-feeding success, blood volume and adult survivorship post-blood meal were assessed. Results The An. gambiae mosquitoes carrying the kdr R allele (KisKdr) laid a reduced number of eggs. The mean number of larvae in the susceptible strain Kisumu was three-fold overall higher than that seen in the KisKdr strain with a significant difference in hatching rates (81.89% in Kisumu vs 72.89% in KisKdr). The KisKdr larvae had a significant higher survivorship than that of Kisumu. The blood-feeding success was significantly higher in the resistant mosquitoes (84%) compared to the susceptible ones (34.75%). However, the mean blood volume was 1.36 µL/mg, 1.45 µL/mg and 1.68 µL/mg in Kisumu, homozygote and heterozygote KisKdr mosquitoes, respectively. After blood-feeding, the heterozygote KisKdr mosquitoes displayed highest survivorship when compared to that of Kisumu. Conclusions The presence of the knockdown resistance allele appears to impact the life-history traits, such as fecundity, fertility, larval survivorship, and blood-feeding behaviour in An. gambiae. These data could help to guide the implementation of more reliable strategies for the control of malaria vectors.

Published
2021
Full Text
View/download PDF

2. Multiple insecticide resistance and Plasmodium infection in the principal malaria vectors Anopheles funestus and Anopheles gambiae in a forested locality close to the Yaoundé airport, Cameroon [version 2; peer review: 2 approved]

Author

Francis N. Nkemngo, Leon M. J. Mugenzi, Ebai Terence, Abdoulaye Niang, Murielle J. Wondji, Micareme Tchoupo, Nguiffo D. Nguete, Williams Tchapga, Helen Irving, Jacques D. M. Ntabi, Romuald Agonhossou, Terence S. Boussougou-Sambe, Romaric B. Akoton, Felix Koukouikila-Koussounda, Yudi T. Pinilla, Francine Ntoumi, Luc S. Djogbenou, Stephen M. Ghogomu, Cyrille Ndo, Ayola A. Adegnika, Steffen Borrmann, and Charles S. Wondji

Subjects
Medicine, Science
Abstract

Background: Reducing the burden of malaria requires better understanding of vector populations, particularly in forested regions where the incidence remains elevated. Here, we characterized malaria vectors in a locality near the Yaoundé international airport, Cameroon, including species composition, abundance, Plasmodium infection rate, insecticide resistance profiles and underlying resistance mechanisms. Methods: Blood-fed adult mosquitoes resting indoors were aspirated from houses in April 2019 at Elende, a locality situated 2 km from the Yaoundé-Nsimalen airport. Female mosquitoes were forced to lay eggs to generate F 1 adults. Bioassays were performed to assess resistance profile to the four insecticides classes. The threshold of insecticide susceptibility was defined above 98% mortality rate and mortality rates below 90% were indicative of confirmed insecticide resistance. Furthermore, the molecular basis of resistance and Plasmodium infection rates were investigated. Results: Anopheles funestus s.s. was the most abundant species in Elende (85%) followed by Anopheles gambiae s.s. (15%) with both having similar sporozoite rate. Both species exhibited high levels of resistance to the pyrethroids, permethrin and deltamethrin (

Published
2020
Full Text
View/download PDF

3. Multiple insecticide resistance and Plasmodium infection in the principal malaria vectors Anopheles funestus and Anopheles gambiae in a forested locality close to the Yaoundé airport, Cameroon

Author

Nguiffo D. Nguete, Ebai Terence, Williams Tchapga, Murielle J. Wondji, Francis Nongley Nkemngo, Jacques D. M. Ntabi, Ayola A. Adegnika, Steffen Borrmann, Cyrille Ndo, Romuald Agonhossou, Yudi T Pinilla, Leon M. J. Mugenzi, Felix Koukouikila-Koussounda, Charles S. Wondji, Stephen Mbigha Ghogomu, Romaric B Akoton, Luc Djogbenou, Terence S. Boussougou-Sambe, Abdoulaye Niang, Micareme Tchoupo, Francine Ntoumi, and Helen Irving

Subjects
0301 basic medicine, Veterinary medicine, Insecticide resistance, Anopheles gambiae, education, 030231 tropical medicine, Medicine (miscellaneous), Bendiocarb, wa_395, Biology, General Biochemistry, Genetics and Molecular Biology, Anopheles funestus, 03 medical and health sciences, chemistry.chemical_compound, Dieldrin, 0302 clinical medicine, parasitic diseases, medicine, Cameroon, Plasmodium infection, 2. Zero hunger, Anopheles vectors, Pyrethroid, Mortality rate, wa_240, Articles, medicine.disease, biology.organism_classification, Vector control, Malaria, wc_750, 3. Good health, 030104 developmental biology, Deltamethrin, Multiple insecticide resistance, chemistry, qx_510, Plasmodium sporozoite infection, qx_515, Research Article, Permethrin, medicine.drug
Abstract

Background:Reducing the burden of malaria requires better understanding of vector populations, particularly in forested regions where the incidence remains elevated. Here, we characterized malaria vectors in a locality near the Yaoundé international airport, Cameroon, including species composition, abundance,Plasmodiuminfection rate, insecticide resistance profiles and underlying resistance mechanisms.Methods:Blood-fed adult mosquitoes resting indoors were aspirated from houses in April 2019 at Elende, a locality situated 2 km from the Yaoundé-Nsimalen airport. Female mosquitoes were forced to lay eggs to generate F1adults. Bioassays were performed to assess resistance profile to the four insecticides classes. The threshold of insecticide susceptibility was defined above 98% mortality rate and mortality rates below 90% were indicative of confirmed insecticide resistance. Furthermore, the molecular basis of resistance andPlasmodiuminfection rates were investigated.Results:Anopheles funestuss.s. was the most abundant species in Elende (85%) followed byAnopheles gambiaes.s. (15%) with both having similar sporozoite rate. Both species exhibited high levels of resistance to the pyrethroids, permethrin and deltamethrin (An. gambiaes.s. was resistant to DDT (9.9% mortality) and bendiocarb (54% mortality) while susceptible to organophosphate.An. funestuss.s. was resistant to dieldrin (1% mortality), DDT (86% mortality) but susceptible to carbamates and organophosphates. The L119F-GSTe2 resistance allele (8%) and G119Sace-1 resistance allele (15%) were detected inAn. funestuss.s. andAn. gambiaes.s., respectively.Furthermore, the high pyrethroid/DDT resistances inAn. gambiaecorresponded with an increase frequency of 1014Fkdrallele (95%). Transcriptional profiling of candidate cytochrome P450 genes reveals the over-expression ofCYP6P5,CYP6P9aandCYP6P9b.Conclusion:The resistance to multiple insecticide classes observed in these vector populations alongside the significantPlasmodiumsporozoite rate highlights the challenges that vector control programs encounter in sustaining the regular benefits of contemporary insecticide-based control interventions in forested areas.

Published
2020

4. Experimental huts trial of the efficacy of pyrethroids/piperonyl butoxide (PBO) net treatments for controlling multi-resistant populations of Anopheles funestus s.s. in Kpomè, Southern Benin

Author

Michael Seun Atoyebi, Rousseau Djouaka, Innocent Djègbè, Francis Zeukeng, Romaric B Akoton, Charles S. Wondji, Genevieve M. Tchigossou, Pelagie Boko, Jacob M. Riveron, Razack Adeoti, Kabirou Moutairou, Akadiri Yessoufou, Eric Tossou, and Helen Irving

Subjects
0301 basic medicine, Piperonyl butoxide, LLINs, Anopheles gambiae, 030231 tropical medicine, Medicine (miscellaneous), wa_395, wc_765, An. coluzzii, General Biochemistry, Genetics and Molecular Biology, World health, wa_110, PBO, Toxicology, 03 medical and health sciences, chemistry.chemical_compound, 0302 clinical medicine, An. funestus s.s, parasitic diseases, medicine, Pyrethroids, Multi-resistance controlling, biology, Anopheles funestus, Anopheles, wa_240, Articles, biology.organism_classification, medicine.disease, Resistant tuberculosis, 3. Good health, wc_750, 030104 developmental biology, chemistry, qx_510, qx_515, Malaria control, Malaria, Research Article
Abstract

Background:Insecticides resistance inAnophelesmosquitoes limits Long-Lasting Insecticidal Nets (LLIN) used for malaria control in Africa, especially Benin. This study aimed to evaluate the bio-efficacy of current LLINs in an area whereAn. funestuss.l.andAn. gambiaehave developed multi-resistance to insecticides, and to assess in experimental huts the performance of a mixed combination of pyrethroids and piperonyl butoxide (PBO) treated nets on these resistant mosquitoes.Methods:The study was conducted at Kpomè, Southern Benin. The bio-efficacy of LLINs againstAn. funestus and An. gambiaewas assessed using the World Health Organization (WHO) cone and tunnel tests. A released/recapture experiment following WHO procedures was conducted to compare the efficacy of conventional LLINs treated with pyrethroids only and LLINs with combinations of pyrethroids and PBO. Prior to huts trials, we confirmed the level of insecticide and PBO residues in tested nets using high performance liquid chromatography (HPLC).Results:Conventional LLINs (Type 2 and Type 4) have the lowest effect against local multi-resistantAn. funestus s.s. and An. coluzziipopulations from Kpomè. Conversely, when LLINs containing mixtures of pyrethroids and PBO (Type 1 and Type 3) were introduced in trial huts, we recorded a greater effect against the two mosquito populations (P < 0.0001). Tunnel test withAn. funestus s.s.revealed mortalities of over 80% with this new generation of LLINs (Type 1 and Type 3),while conventional LLINs produced 65.53 ± 8.33% mortalities for Type 2 and 71.25 ±7.92% mortalities for Type 4. Similarly, mortalities ranging from 77 to 87% were recorded with the local populations ofAn. coluzzii.Conclusion:This study suggests the reduced efficacy of conventional LLINs (Pyrethroids alone) currently distributed in Benin communities whereAnophelespopulations have developed multi-insecticide resistance. The new generation nets (pyrethroids+PBO) proved to be more effective on multi-resistant populations of mosquitoes.

Published
2018

Catalog

Books, media, physical & digital resources
See catalog results