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Althoff RA, Huijben S. Comparison of the variability in mortality data generated by CDC bottle bioassay, WHO tube test, and topical application bioassay using Aedes aegypti mosquitoes. Parasit Vectors 2022; 15:476. [PMID: 36539831 PMCID: PMC9769033 DOI: 10.1186/s13071-022-05583-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2022] [Accepted: 11/08/2022] [Indexed: 12/24/2022] Open
Abstract
BACKGROUND Insecticide resistance remains a major public health problem. Resistance surveillance is critical for effective vector control and resistance management planning. Commonly used insecticide susceptibility bioassays for mosquitoes are the CDC bottle bioassay and the WHO tube test. Less commonly used in the field but considered the gold standard for assessing insecticide susceptibility in the development of novel insecticides is the topical application bioassay. Each of these bioassays has critical differences in how they assess insecticide susceptibility that impacts their ability to differentiate between resistant and susceptible populations or determine different levels of resistance intensity. METHODS We compared the CDC bottle bioassay, the WHO tube test, and the topical application bioassay in establishing the dose-response against deltamethrin (DM) using the DM-resistant Aedes aegypti strain MC1. Mosquitoes were exposed to a range of insecticide concentrations to establish a dose-response curve and assess variation around model predictions. In addition, 10 replicates of 20-25 mosquitoes were exposed to a fixed dose with intermediate mortality to assess the degree of variation in mortality. RESULTS The topical application bioassay exhibited the lowest amount of variation in the dose-response data, followed by the WHO tube test. The CDC bottle bioassay had the highest level of variation. In the fixed-dose experiment, a higher variance was similarly found for the CDC bottle bioassay compared with the WHO tube test and topical application bioassay. CONCLUSION These data suggest that the CDC bottle bioassay has the lowest power and the topical application bioassay the highest power to differentiate between resistant and susceptible populations and assess changes over time and between populations. This observation has significant implications for the interpretation of surveillance results from different assays. Ultimately, it will be important to discuss optimal insecticide resistance surveillance tools in terms of the surveillance objective, practicality in the field, and accuracy of the tool to reach that objective.
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Affiliation(s)
- Rachel A. Althoff
- grid.215654.10000 0001 2151 2636The Center for Evolution & Medicine, School of Life Sciences, Arizona State University, Tempe, AZ USA
| | - Silvie Huijben
- grid.215654.10000 0001 2151 2636The Center for Evolution & Medicine, School of Life Sciences, Arizona State University, Tempe, AZ USA ,grid.215654.10000 0001 2151 2636Computational and Modeling Sciences Center, Simon A. Levin Mathematical, Arizona State University, Tempe, AZ USA
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2
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Zhou Y, Zhang WX, Tembo E, Xie MZ, Zhang SS, Wang XR, Wei TT, Feng X, Zhang YL, Du J, Liu YQ, Zhang X, Cui F, Lu QB. Effectiveness of indoor residual spraying on malaria control: a systematic review and meta-analysis. Infect Dis Poverty 2022; 11:83. [PMID: 35870946 PMCID: PMC9308352 DOI: 10.1186/s40249-022-01005-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2022] [Accepted: 06/30/2022] [Indexed: 11/18/2022] Open
Abstract
Background Indoor residual spraying (IRS) is one of the key interventions recommended by World Health Organization in preventing malaria infection. We aimed to conduct a systematic review and meta-analysis of global studies about the impact of IRS on malaria control. Method We searched PubMed, Web of Science, Embase, and Scopus for relevant studies published from database establishment to 31 December 2021. Random-effects models were used to perform meta-analysis and subgroup analysis to pool the odds ratio (OR) and 95% confidence interval (CI). Meta-regression was used to investigate potential factors of heterogeneity across studies. Results Thirty-eight articles including 81 reports and 1,174,970 individuals were included in the meta-analysis. IRS was associated with lower rates of malaria infection (OR = 0.35, 95% CI: 0.27–0.44). The significantly higher effectiveness was observed in IRS coverage ≥ 80% than in IRS coverage < 80%. Pyrethroids was identified to show the greatest performance in malaria control. In addition, higher effectiveness was associated with a lower gross domestic product
as well as a higher coverage of IRS and bed net utilization. Conclusions IRS could induce a positive effect on malaria infection globally. The high IRS coverage and the use of pyrethroids are key measures to reduce malaria infection. More efforts should focus on increasing IRS coverage, developing more effective new insecticides against malaria, and using multiple interventions comprehensively to achieve malaria control goals. Supplementary Information The online version contains supplementary material available at 10.1186/s40249-022-01005-8.
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Pinda PG, Eichenberger C, Ngowo HS, Msaky DS, Abbasi S, Kihonda J, Bwanaly H, Okumu FO. Comparative assessment of insecticide resistance phenotypes in two major malaria vectors, Anopheles funestus and Anopheles arabiensis in south-eastern Tanzania. Malar J 2020; 19:408. [PMID: 33176805 PMCID: PMC7661194 DOI: 10.1186/s12936-020-03483-3] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2020] [Accepted: 11/05/2020] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Long-lasting insecticide-treated nets (LLINs) and indoor residual spraying (IRS) have greatly reduced malaria transmission in sub-Saharan Africa, but are threatened by insecticide resistance. In south-eastern Tanzania, pyrethroid-resistant Anopheles funestus are now implicated in > 80% of malaria infections, even in villages where the species occurs at lower densities than the other vector, Anopheles arabiensis. This study compared the insecticide resistance phenotypes between the two malaria vectors in an area where pyrethroid-LLINs are widely used. METHODS The study used the World Health Organization (WHO) assays with 1×, 5× and 10× insecticide doses to assess levels of resistance, followed by synergist bioassays to understand possible mechanisms of the observed resistance phenotypes. The tests involved adult mosquitoes collected from three villages across two districts in south-eastern Tanzania and included four insecticide classes. FINDINGS At baseline doses (1×), both species were resistant to the two candidate pyrethroids (permethrin and deltamethrin), but susceptible to the organophosphate (pirimiphos-methyl). Anopheles funestus, but not An. arabiensis was also resistant to the carbamate (bendiocarb). Both species were resistant to DDT in all villages except in one village where An. arabiensis was susceptible. Anopheles funestus showed strong resistance to pyrethroids, surviving the 5× and 10× doses, while An. arabiensis reverted to susceptibility at the 5× dose. Pre-exposure to the synergist, piperonyl butoxide (PBO), enhanced the potency of the pyrethroids against both species and resulted in full susceptibility of An. arabiensis (> 98% mortality). However, for An. funestus from two villages, permethrin-associated mortalities after pre-exposure to PBO only exceeded 90% but not 98%. CONCLUSIONS In south-eastern Tanzania, where An. funestus dominates malaria transmission, the species also has much stronger resistance to pyrethroids than its counterpart, An. arabiensis, and can survive more classes of insecticides. The pyrethroid resistance in both species appears to be mostly metabolic and may be partially addressed using synergists, e.g. PBO. These findings may explain the continued persistence and dominance of An. funestus despite widespread use of pyrethroid-treated LLINs, and inform new intervention choices for such settings. In short and medium-term, these may include PBO-based LLINs or improved IRS with compounds to which the vectors are still susceptible.
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Affiliation(s)
- Polius G Pinda
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Morogoro, United Republic of Tanzania.
| | - Claudia Eichenberger
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Morogoro, United Republic of Tanzania.,Swiss Tropical and Public Health Institute, Basel, Switzerland
| | - Halfan S Ngowo
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Morogoro, United Republic of Tanzania.,Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow, UK
| | - Dickson S Msaky
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Morogoro, United Republic of Tanzania
| | - Said Abbasi
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Morogoro, United Republic of Tanzania
| | - Japhet Kihonda
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Morogoro, United Republic of Tanzania
| | - Hamis Bwanaly
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Morogoro, United Republic of Tanzania
| | - Fredros O Okumu
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Morogoro, United Republic of Tanzania. .,Nelson Mandela African Institution of Science and Technology, School of Life Sciences and Biotechnology, Arusha, United Republic of Tanzania. .,School of Public Health, University of the Witwatersrand, Parktown, South Africa. .,Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow, UK.
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4
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Hancock PA, Hendriks CJM, Tangena JA, Gibson H, Hemingway J, Coleman M, Gething PW, Cameron E, Bhatt S, Moyes CL. Mapping trends in insecticide resistance phenotypes in African malaria vectors. PLoS Biol 2020; 18:e3000633. [PMID: 32584814 PMCID: PMC7316233 DOI: 10.1371/journal.pbio.3000633] [Citation(s) in RCA: 57] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2019] [Accepted: 05/11/2020] [Indexed: 11/25/2022] Open
Abstract
Mitigating the threat of insecticide resistance in African malaria vector populations requires comprehensive information about where resistance occurs, to what degree, and how this has changed over time. Estimating these trends is complicated by the sparse, heterogeneous distribution of observations of resistance phenotypes in field populations. We use 6,423 observations of the prevalence of resistance to the most important vector control insecticides to inform a Bayesian geostatistical ensemble modelling approach, generating fine-scale predictive maps of resistance phenotypes in mosquitoes from the Anopheles gambiae complex across Africa. Our models are informed by a suite of 111 predictor variables describing potential drivers of selection for resistance. Our maps show alarming increases in the prevalence of resistance to pyrethroids and DDT across sub-Saharan Africa from 2005 to 2017, with mean mortality following insecticide exposure declining from almost 100% to less than 30% in some areas, as well as substantial spatial variation in resistance trends.
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Affiliation(s)
| | | | - Julie-Anne Tangena
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, United Kingdom
| | - Harry Gibson
- Big Data Institute, University of Oxford, Oxford, United Kingdom
| | - Janet Hemingway
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, United Kingdom
| | - Michael Coleman
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, United Kingdom
| | - Peter W. Gething
- Telethon Kids Institute, Perth Children's Hospital, Perth, Australia
- Curtin University, Bentley, Perth, Australia
| | - Ewan Cameron
- Big Data Institute, University of Oxford, Oxford, United Kingdom
| | - Samir Bhatt
- Department of Infectious Disease Epidemiology, Imperial College, St Mary’s Hospital, London, United Kingdom
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Bekono BD, Ntie-Kang F, Onguéné PA, Lifongo LL, Sippl W, Fester K, Owono LCO. The potential of anti-malarial compounds derived from African medicinal plants: a review of pharmacological evaluations from 2013 to 2019. Malar J 2020; 19:183. [PMID: 32423415 PMCID: PMC7236213 DOI: 10.1186/s12936-020-03231-7] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2020] [Accepted: 04/08/2020] [Indexed: 02/07/2023] Open
Abstract
Background African Traditional Medicine (ATM) is used for the healthcare of about 80% of the rural populations of the continent of Africa. The practices of ATM make use of plant-products, which are known to contain plant-based secondary metabolites or natural products (NPs), likely to play key roles in drug discovery, particularly as lead compounds. For various reasons, including resistance of strains of Plasmodium to known anti-malarial drugs, local African populations often resort to plant-based treatments and/or a combination of this and standard anti-malarial regimens. Emphasis has been laid in this review to present the anti-malarial virtue of the most recently published phytochemicals or natural products, which have been tested by in vitro and in vivo assays. Methods The data was based on the current version of the African Compound Libraries, which are constantly being updated based on inputs from journal articles and student theses (M.Sc/Ph.D) from African University libraries. Emphasis was laid on data published after 2012. In order to carry out the original data collection, currently being included in the African Compounds Database, individual journal websites were queried using the country names in Africa as search terms. Over 40,000 articles “hits” were originally retrieved, then reduced to about 9000 articles. The retained articles/theses was further queried with the search terms “malaria”, “malarial”, “plasmodium”, “plasmodial” and a combination of them, resulting in over 500 articles. Those including compounds with anti-malarial activities for which the measured activities fell within the established cut off values numbered 55, which were all cited in the review as relevant references. Results and discussion Pure compounds derived from African medicinal plants with demonstrated anti-malarial/antiplasmodial properties with activities ranging from “very active” to “weakly active” have been discussed. The majority of the 187 natural products were terpenoids (30%), followed by flavonoids (22%), alkaloids (19%) and quinones (15%), with each of the other compound classes being less than 5% of the entire compound collection. It was also observed that most of the plant species from which the compounds were identified were of the families Rubiaceae, Meliaceae and Asphodelaceae. The review is intended to continue laying the groundwork for an African-based anti-malarial drug discovery project.
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Affiliation(s)
- Boris D Bekono
- Department of Physics, Ecole Normale Supérieure, University of Yaoundé I, P. O. Box 47, Yaoundé, Cameroon
| | - Fidele Ntie-Kang
- Department of Chemistry, Faculty of Science, University of Buea, P. O. Box 63, Buea, Cameroon. .,Department of Pharmaceutical Chemistry, Martin-Luther University of Halle-Wittenberg, Kurt-Mothes Str. 3, 06120, Halle (Saale), Germany. .,Institut für Botanik, Technische Universität Dresden, Zellescher Weg 20b, 01062 , Dresden, Germany.
| | - Pascal Amoa Onguéné
- Department of Chemistry, University Institute of Wood Technology Mbalmayo, University of Yaoundé I, BP 50, Mbalmayo, Cameroon
| | - Lydia L Lifongo
- Department of Chemistry, Faculty of Science, University of Buea, P. O. Box 63, Buea, Cameroon
| | - Wolfgang Sippl
- Department of Pharmaceutical Chemistry, Martin-Luther University of Halle-Wittenberg, Kurt-Mothes Str. 3, 06120, Halle (Saale), Germany
| | - Karin Fester
- Faculty of Natural and Environmental Sciences, Zittau/Görlitz University of Applied Sciences, Theodor-Körner-Allee 16, 02763, Zittau, Germany
| | - Luc C O Owono
- Department of Physics, Ecole Normale Supérieure, University of Yaoundé I, P. O. Box 47, Yaoundé, Cameroon.
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Fagbohun IK, Idowu ET, Otubanjo OA, Awolola TS. First report of AChE1 (G119S) mutation and multiple resistance mechanisms in Anopheles gambiae s.s. in Nigeria. Sci Rep 2020; 10:7482. [PMID: 32366848 PMCID: PMC7198501 DOI: 10.1038/s41598-020-64412-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2019] [Accepted: 04/16/2020] [Indexed: 11/10/2022] Open
Abstract
Susceptibility and PBO synergist bioassays were done using 3–5 days old female Anopheles mosquito collected from Lagos State, Nigeria with WHO test papers DDT (4%), permethrin (0.75%), Bendiocarb (1%) and PBO (4%) according to standard procedures. The activities of cytochrome P450s, glutathione S-transferase and carboxylesterases were determined using biochemical assays. The presence of kdr-w, kdr-e and Ace-1R mutations were examined using molecular assays. Resistance to DDT and permethrin in An gambiae s.s from the four Local Government Areas (LGAs) was recorded while suspected resistance to bendiocarb was recorded in mosquitoes from Alimosho and Kosofe LGAs. PBO synergist reduced the knockdown time and also recorded significantly (P < 0.05) higher 24 hrs percentage mortality compared to non-synergized bioassays. Increased activities of detoxifying enzymes was recorded in wild mosquito compared to the insecticides susceptible laboratory strain and this was significant (P < 0.05) in P450s, esterase α and β. Kdr-w was detected in An. gambiae s.s from all the LGAs, kdr-e (L1014S) was detected in Alimosho, Kosofe and Ibeju-Lekki, while the Ace-1R gene was detected in Alimosho and Kosofe. Results from this study provide evidence for resistance of An. gambiae from Lagos State to multiple classes of neurotoxic insecticides with multiple resistance mechanisms to these insecticides.
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Eremeeva ME, Warang SS, Anderson ML, Capps D, Zohdy S, Durden LA. Molecular Survey for Pathogens and Markers of Permethrin Resistance in Human Head Lice (Phthiraptera: Pediculidae) from Madagascar. J Parasitol 2019. [DOI: 10.1645/18-146] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Affiliation(s)
- Marina E. Eremeeva
- Jiann-Ping Hsu College of Public Health, Georgia Southern University, 501 Forest Drive, P.O. Box 8015, Statesboro, Georgia 30458
| | - Shamta S. Warang
- Jiann-Ping Hsu College of Public Health, Georgia Southern University, 501 Forest Drive, P.O. Box 8015, Statesboro, Georgia 30458
| | - Matthew L. Anderson
- Jiann-Ping Hsu College of Public Health, Georgia Southern University, 501 Forest Drive, P.O. Box 8015, Statesboro, Georgia 30458
| | - Danielle Capps
- Jiann-Ping Hsu College of Public Health, Georgia Southern University, 501 Forest Drive, P.O. Box 8015, Statesboro, Georgia 30458
| | - Sarah Zohdy
- School of Forestry & Wildlife Sciences, Auburn University, Auburn, Alabama 36849
| | - Lance A. Durden
- College of Science and Mathematics, Georgia Southern University, P.O. Box 8042-1, Statesboro, Georgia 30458
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8
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Tchouakui M, Fossog BT, Ngannang BV, Djonabaye D, Tchapga W, Njiokou F, Wondji CS. Investigation of the influence of a glutathione S-transferase metabolic resistance to pyrethroids/DDT on mating competitiveness in males of the African malaria vector, Anopheles funestus. Wellcome Open Res 2019; 4:13. [PMID: 31069259 PMCID: PMC6480967 DOI: 10.12688/wellcomeopenres.15013.2] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/18/2019] [Indexed: 01/16/2023] Open
Abstract
Background: Metabolic resistance is a serious challenge to current insecticide-based interventions. The extent to which it affects natural populations of mosquitoes including their reproduction ability remains uncharacterised. Here, we investigated the potential impact of the glutathione S-transferase L119F-GSTe2 resistance on the mating competitiveness of male Anopheles funestus, in Cameroon. Methods: Swarms and indoor resting collections took place in March, 2018 in Tibati, Cameroon. WHO tube and cone assays were performed on F 1 mosquitoes from indoor collected females to assess the susceptibility profile of malaria vectors. Mosquitoes mated and unmated males collected in the swarms were genotyped for the L119F metabolic marker to assess its association with mating male competitiveness. Results: Susceptibility and synergist assays, showed that this population was multiple resistant to pyrethroids, DDT and carbamates, likely driven by metabolic resistance mechanisms. Cone assays revealed a reduced efficacy of standard pyrethroid-nets (Olyset and PermaNet 2.0) with low mortality (<25%) whereas synergist PBO-Nets (Olyset Plus and PermaNet 3.0) retained greater efficacy with higher mortality (>80%). The L119F-GSTe2 mutation, conferring pyrethroid/DDT resistance, was detected in this An. funestus population at a frequency of 28.8%. In addition, a total of 15 mating swarms were identified and 21 An. funestus couples were isolated from those swarms. A comparative genotyping of the L119F-GSTe2 mutation between mated and unmated males revealed that heterozygote males 119L/F-RS were less able to mate than homozygote susceptible (OR=7.2, P<0.0001). Surprisingly, heterozygote mosquitoes were also less able to mate than homozygote resistant (OR=4.2, P=0.010) suggesting the presence of a heterozygote disadvantage effect. Overall, mosquitoes bearing the L119-S susceptible allele were significantly more able to mate than those with 119F-R resistant allele (OR=2.1, P=0.03). Conclusion: This study provides preliminary evidences that metabolic resistance potentially exerts a fitness cost on mating competiveness in resistant mosquitoes.
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Affiliation(s)
- Magellan Tchouakui
- Department of Animal Biology and Physiology, Faculty of Science, University of Yaoundé 1, Yaoundé, P.O. Box 812, Cameroon
- Department of Medical Entomology, Centre for Research in Infectious Diseases, Younde, 13591, Cameroon
| | - Billy Tene Fossog
- Department of Medical Entomology, Centre for Research in Infectious Diseases, Younde, 13591, Cameroon
| | - Brigitte Vanessa Ngannang
- Department of Medical Entomology, Centre for Research in Infectious Diseases, Younde, 13591, Cameroon
- Department of Biochemistry, University of Yaoundé 1, Yaoundé, P.O. Box 812, Cameroon
| | - Doumani Djonabaye
- Department of Medical Entomology, Centre for Research in Infectious Diseases, Younde, 13591, Cameroon
- Department of Biochemistry, University of Yaoundé 1, Yaoundé, P.O. Box 812, Cameroon
| | - Williams Tchapga
- Department of Medical Entomology, Centre for Research in Infectious Diseases, Younde, 13591, Cameroon
| | - Flobert Njiokou
- Department of Animal Biology and Physiology, Faculty of Science, University of Yaoundé 1, Yaoundé, P.O. Box 812, Cameroon
| | - Charles S. Wondji
- Department of Medical Entomology, Centre for Research in Infectious Diseases, Younde, 13591, Cameroon
- Department of Vector Biology, Liverpool School of Tropical Medicine,, Pembroke Place, L35QA, Liverpool, UK, UK
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Mazigo E, Kidima W, Myamba J, Kweka EJ. The impact of Anopheles gambiae egg storage for mass rearing and production success. Malar J 2019; 18:52. [PMID: 30808356 PMCID: PMC6390356 DOI: 10.1186/s12936-019-2691-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2018] [Accepted: 02/21/2019] [Indexed: 12/22/2022] Open
Abstract
BACKGROUND Mass rearing requires a large colony from which male individuals can be harvested for sterilization and release. Attention is needed when monitoring life parameters of the reared population, knowing that any variations within the target population would lead to mismatching between two populations. The aim of this study was to assess the impact of Anopheles gambiae sensu stricto (s.s.) egg storage on hatchability and life history traits. For each parameter, comparison was made between freshly laid and stored eggs in three densities (40, 80, 120 eggs). METHODS Anopheles gambiae s.s. freshly laid eggs were collected from the Tropical Pesticide Research Institute (TPRI) insectary. Eggs to be stored were kept at - 20 °C for 10 min and then transferred to refrigerators at 4 °C for intervals of 5, 10, 15, 20, and 25 days. After respective storage days, the eggs were transferred from refrigerators to ambient temperature of (25 ± 2) °C for 24 h and then placed in incubators for 24 h. Thereafter eggs were hatched. The egg hatchability, emerged larvae development, larvae survival and emerged adult sex ratios were monitored. RESULTS This study found that hatching rates decreased with increase in storage time. The difference was significant in eggs stored for 10 and 15 days (P < 0.05). There were no significant differences in hatching rates between An. gambiae eggs stored for 5 days and freshly hatched eggs (P > 0.05). Anopheles larvae development (L1 to pupae) was not significantly affected by storage time across all hatching densities. The study also found that larvae survival decreased with increase in egg storage time. However, there was no significant difference between larvae from freshly hatched eggs and those from eggs at 5 and 10 storage days (P > 0.05) but not for eggs stored for 15 days. Furthermore, there was a decrease in emerged adult males and increase in females relative to increased time of egg storage. The difference was significant (P < 0.05) at 15 storage days but not for eggs stored for 5 and 10 days (in triplicate densities). CONCLUSION From this study it was concluded that storing An. gambiae eggs at 4 °C and 48 ± 2% relative humidity (RH) for 5 days is the optimal condition and time that did not affect egg hatching rates, larval development and survivorship and emerged adult mosquito sex ratio.
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Affiliation(s)
- Ernest Mazigo
- Department of Zoology and Wildlife Conservation, College of Natural and Applied Sciences, University of Dar es Salaam, Dar es Salaam, Tanzania
| | - Winifrida Kidima
- Department of Zoology and Wildlife Conservation, College of Natural and Applied Sciences, University of Dar es Salaam, Dar es Salaam, Tanzania
| | - Joseph Myamba
- National Institute for Medical Research, Amani Medical Research Centre, P.O. Box 81, Muheza, Tanzania
| | - Eliningaya J Kweka
- Department of Medical Parasitology, School of Medicine, Catholic University of Health and Allied Sciences-Bugando, P.O. Box 1464, Mwanza, Tanzania. .,Division of Livestock and Human Disease Vector Control, Tropical Pesticides Research Institute, P.O.Box 3024, Arusha, Tanzania.
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10
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Tchouakui M, Fossog BT, Ngannang BV, Djonabaye D, Tchapga W, Njiokou F, Wondji CS. Investigation of the influence of a glutathione S-transferase metabolic resistance to pyrethroids/DDT on mating competitiveness in males Anopheles funestus, African malaria vector. Wellcome Open Res 2019; 4:13. [PMID: 31069259 PMCID: PMC6480967 DOI: 10.12688/wellcomeopenres.15013.1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/21/2019] [Indexed: 10/12/2023] Open
Abstract
Background: Metabolic resistance is a serious challenge to current insecticide-based interventions. The extent to which it affects natural populations of mosquitoes including their reproduction ability remains uncharacterised. Here, we investigated the potential impact of the glutathione S-transferase L119F-GSTe2 resistance on the mating competitiveness of male Anopheles funestus, in Cameroon. Methods: Swarms and indoor resting collections took place in March, 2018 in Tibati, Cameroon. WHO tube and cone assays were performed on F 1 mosquitoes from indoor collected females to assess the susceptibility profile of malaria vectors. Mosquitoes mated and unmated males collected in the swarms were genotyped for the L119F metabolic marker to assess its association with mating male competitiveness. Results: Susceptibility and synergist assays, showed that this population was multiple resistant to pyrethroids, DDT and carbamates, likely driven by metabolic resistance mechanisms. Cone assays revealed a reduced efficacy of standard pyrethroid-nets (Olyset and PermaNet 2.0) with low mortality (<25%) whereas synergist PBO-Nets (Olyset Plus and PermaNet 3.0) retained greater efficacy with higher mortality (>80%). The L119F-GSTe2 mutation, conferring pyrethroid/DDT resistance, was detected in this An.funestus population at a frequency of 28.8%. In addition, a total of 15 mating swarms were identified and 21 An. funestus couples were isolated from those swarms. A comparative genotyping of the L119F-GSTe2 mutation between mated and unmated males revealed that heterozygote males 119L/F-RS were less able to mate than homozygote susceptible (OR=7.2, P<0.0001). Surprisingly, heterozygote mosquitoes were also less able to mate than homozygote resistant (OR=4.2, P=0.010) suggesting the presence of a heterozygote disadvantage effect. Overall, mosquitoes bearing the L119-S susceptible allele were significantly more able to mate than those with 119F-R resistant allele (OR=2.1, P=0.03). Conclusion: This study provides preliminary evidences that metabolic resistance potentially exerts a fitness cost on mating competiveness in resistant mosquitoes.
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Affiliation(s)
- Magellan Tchouakui
- Department of Animal Biology and Physiology, Faculty of Science, University of Yaoundé 1, Yaoundé, P.O. Box 812, Cameroon
- Department of Medical Entomology, Centre for Research in Infectious Diseases, Younde, 13591, Cameroon
| | - Billy Tene Fossog
- Department of Medical Entomology, Centre for Research in Infectious Diseases, Younde, 13591, Cameroon
| | - Brigitte Vanessa Ngannang
- Department of Medical Entomology, Centre for Research in Infectious Diseases, Younde, 13591, Cameroon
- Department of Biochemistry, University of Yaoundé 1, Yaoundé, P.O. Box 812, Cameroon
| | - Doumani Djonabaye
- Department of Medical Entomology, Centre for Research in Infectious Diseases, Younde, 13591, Cameroon
- Department of Biochemistry, University of Yaoundé 1, Yaoundé, P.O. Box 812, Cameroon
| | - Williams Tchapga
- Department of Medical Entomology, Centre for Research in Infectious Diseases, Younde, 13591, Cameroon
| | - Flobert Njiokou
- Department of Animal Biology and Physiology, Faculty of Science, University of Yaoundé 1, Yaoundé, P.O. Box 812, Cameroon
| | - Charles S. Wondji
- Department of Medical Entomology, Centre for Research in Infectious Diseases, Younde, 13591, Cameroon
- Department of Vector Biology, Liverpool School of Tropical Medicine,, Pembroke Place, L35QA, Liverpool, UK, UK
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Guntay O, Yikilmaz MS, Ozaydin H, Izzetoglu S, Suner A. Evaluation of Pyrethroid Susceptibility in Culex pipiens of Northern Izmir Province, Turkey. J Arthropod Borne Dis 2018; 12:370-377. [PMID: 30918906 PMCID: PMC6423456] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2018] [Accepted: 10/21/2018] [Indexed: 11/26/2022] Open
Abstract
BACKGROUND Mosquitoes, being a nuisance species, are considered as one of the most important species in public health control programs due to their role as a vector in mosquito-borne diseases observed in humans and animals. We evaluated the susceptibility status of Culex pipiens collected from northern Izmir, Turkey in 2011-16. METHODS Mosquito larvae, collected from three different locations in northern İzmir, were reared in the laboratory. Adult susceptibility bioassays were performed using the WHO insecticide-impregnated papers including deltamethrin 0.05%, permethrin 0.75%, α-cypermethrin 0.05% and cyfluthrin 0.15%. In addition, adult bioassays were performed after the pre-exposure to piperonyl butoxide (PBO) to determine the contribution of P450 detoxification enzymes to the phenotypic resistance. RESULTS In all of the three populations, high levels of resistance were observed (mortalities<63%) to all of the four pyrethroids. Different pyrethroids but with the same mode of action can exhibit significantly different phenotypic resistance in a single population. PBO bioassays also showed that P450 detoxification enzymes can have diverse effects on different pyrethroids. CONCLUSION Using just one chemical in a class of insecticide can be misleading for resistance studies.
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Affiliation(s)
- Onur Guntay
- Section of Molecular Biology, Department of Biology, Faculty of Science, Ege University, Izmir, Turkey
| | - Mehmet Salih Yikilmaz
- Section of Molecular Biology, Department of Biology, Faculty of Science, Ege University, Izmir, Turkey
| | - Huseyin Ozaydin
- Section of Molecular Biology, Department of Biology, Faculty of Science, Ege University, Izmir, Turkey
| | - Savas Izzetoglu
- Section of Molecular Biology, Department of Biology, Faculty of Science, Ege University, Izmir, Turkey,Corresponding author: Dr Savas Izzetoglu, E-mail:
| | - Asli Suner
- Department of Biostatistics and Medical Informatics, Faculty of Medicine, Ege University, Izmir, Turkey
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Evidence of Insecticide Resistance to Pyrethroids and Bendiocarb in Anopheles funestus from Tsararano, Marovoay District, Madagascar. BIOMED RESEARCH INTERNATIONAL 2018; 2018:5806179. [PMID: 30402485 PMCID: PMC6196927 DOI: 10.1155/2018/5806179] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/05/2018] [Revised: 05/17/2018] [Accepted: 09/20/2018] [Indexed: 12/12/2022]
Abstract
Introduction In Madagascar, malaria control relies on the countrywide use of long lasting insecticide treated bed nets (LLINs) and on indoor residual spraying (IRS) in the central highland area as well as a small area on the eastern coast. We tested insecticide resistance mechanisms of Anopheles funestus from Tsararano, a malaria endemic village in the coastal health district of Marovoay. Methods Insecticide susceptibility bioassays were done in July 2017 on first-generation Anopheles funestus (F1) to assess (i) the susceptibility to permethrin (0.05%), deltamethrin (0.05%), DDT (4%), malathion (5%), fenitrothion (1%), and bendiocarb (0.1%); (ii) the effect of preexposure to the piperonyl butoxide (PBO) synergist; and (iii) the enzymatic activities of cytochrome P450, esterases, and glutathione S-transferases (GST). Results Our results demonstrated that An. funestus was phenotypically resistant to pyrethroids and bendiocarb, with a mortality rate (MR) of 33.6% (95%CI: 24.5-43.7%) and 86% (95%CI: 77.6-92.1%), respectively. In contrast, An. funestus were 100% susceptible to DDT and organophosphates (malathion and fenitrothion). Preexposure of An. funestus to PBO synergist significantly restored the susceptibility to bendiocarb (MR=100%) and increased the MR in the pyrethroid group, from 96% (95%CI: 90.0-98.9%) to 100% for deltamethrin and permethrin, respectively (χ2 = 43, df = 3, P< 0.0001). Enzymatic activities of cytochrome P450 and α-esterases were significantly elevated among An. funestus compared with the IPM reference strain (Mann-Whitney U= 30, P<0.0001; U = 145.5, P <0.0001, respectively). No significant differences of β-esterases activities compared to the IPM reference strain were observed (Mann-Whitney U = 392.5, P = 0.08). Conclusion In Tsararano, despite the absence of an IRS programme, there is evidence of high levels of insecticide resistance to pyrethroids and bendiocarb in An.
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Permethrin Susceptibility for the Vector Culex tarsalis and a Nuisance Mosquito Aedes vexans in an Area Endemic for West Nile Virus. BIOMED RESEARCH INTERNATIONAL 2018; 2018:2014764. [PMID: 30112366 PMCID: PMC6077664 DOI: 10.1155/2018/2014764] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/12/2018] [Revised: 05/27/2018] [Accepted: 06/24/2018] [Indexed: 11/17/2022]
Abstract
In 2016, we compared susceptibility to the insecticide, permethrin, between the West Nile virus vector, Culex tarsalis Coquillett, and a major nuisance mosquito, Aedes vexans (Meigen), using baseline diagnostic dose and time values determined using the CDC bottle bioassay protocol. Mosquitoes were collected in the wild in Brookings County, South Dakota, situated in the Northern Great Plains of the USA. The determined diagnostic dose and time were then used in 2017 to validate these measurements for the same 2 mosquito species, collected at a second location within Brookings County. The diagnostic dose was determined for multiple time periods and ranged from 27.0 µg/ml at 60 min to 38.4 µg/ml at 30 min. There was no significant difference detected in mortality rates between Cx. tarsalis and Ae. vexans for any diagnostic time and dose. For practical purposes, mosquitoes in 2017 were tested at 38 µg/ml for 30 min; expected mortality rates were 93.38% for Cx. tarsalis and 94.93% for Ae. vexans. Actual 2017 mortality rates were 92.68% for Cx. tarsalis and 96.12% for Ae. vexans, validating the usefulness of this baseline at an additional location and year.
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