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Waymire E, Samake JN, Gunarathna I, Carter TE. A decade of invasive Anopheles stephensi sequence-based identification: toward a global standard. Trends Parasitol 2024; 40:477-486. [PMID: 38755024 DOI: 10.1016/j.pt.2024.04.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2024] [Revised: 04/15/2024] [Accepted: 04/15/2024] [Indexed: 05/18/2024]
Abstract
Anopheles stephensi is an invasive malaria vector in Africa that has been implicated in malaria outbreaks in the Horn of Africa. In 10 years, it has been detected as far east as Djibouti and as far west as Ghana. Early detections were mostly incidental, but now active surveillance in Africa has been updated to include An. stephensi. Morphological identification of An. stephensi from native vectors can be challenging, thus, sequence-based assays have been used to confirm identification during initial detections. Methods of sequence-based identification of An. stephensi have varied across initial detections to date. Here, we summarize initial detections, make suggestions that could provide a standardized approach, and discuss how sequences can inform additional genomic studies beyond species identification.
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Acford-Palmer H, Phelan JE, Tadesse FG, Kristan M, Collins E, Spadar A, Walker T, Bousema T, Messenger LA, Clark TG, Campino S. Identification of two insecticide resistance markers in Ethiopian Anopheles stephensi mosquitoes using a multiplex amplicon sequencing assay. Sci Rep 2023; 13:5612. [PMID: 37019918 PMCID: PMC10076309 DOI: 10.1038/s41598-023-32336-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2022] [Accepted: 03/26/2023] [Indexed: 04/07/2023] Open
Abstract
Since its first detection in 2012 in Djibouti, Anopheles stephensi has invaded and established in the Horn of Africa, and more recently Nigeria. The expansion of this vector poses a significant threat to malaria control and elimination efforts. Integrated vector management is the primary strategy used to interrupt disease transmission; however, growing insecticide resistance is threatening to reverse gains in global malaria control. We present a next-generation amplicon-sequencing approach, for high-throughput monitoring of insecticide resistance genes (ace1, GSTe2, vgsc and rdl), species identification and characterization of genetic diversity (its2 and cox1) in An. stephensi. Ninety-five An. stephensi mosquitoes, collected in Ethiopia, were screened, identifying 104 SNPs, including the knock-down mutation L958F (L1014F in Musca domestica), and for the first time in this vector species, the A296S substitution (A301S in Drosophila melanogaster) in the rdl locus. Two other amino acid substitutions (ace1-N177D, GSTe2-V189L) were also identified but have not been previously implicated in insecticide resistance. Genetic diversity in the mitochondrial cox1 gene revealed shared haplotypes between Ethiopian An. stephensi with samples from Pakistan, Sudan, and Djibouti. Overall, we present a reliable, cost-effective strategy using amplicon-sequencing to monitor known insecticide resistance mutations, with the potential to identify new genetic variants, to assist in the high-throughput surveillance of insecticide resistance in An. stephensi populations.
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Affiliation(s)
- Holly Acford-Palmer
- Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, UK
| | - Jody E Phelan
- Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, UK
| | - Fitsum G Tadesse
- Malaria and NTD Directorate, Armauer Hansen Research Institute, ALERT Hospital Compound, P.O. Box 1005, Addis Ababa, Ethiopia
| | - Mojca Kristan
- Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, UK
| | - Emma Collins
- Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, UK
| | - Anton Spadar
- Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, UK
| | - Thomas Walker
- Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, UK
| | - Teun Bousema
- Department of Medical Microbiology, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
| | - Louisa A Messenger
- Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, UK
- Environmental and Occupational Health, School of Public Health, University of Nevada, Las Vegas, Las Vegas, USA
| | - Taane G Clark
- Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, UK
- Faculty of Epidemiology and Population Health, London School of Hygiene and Tropical Medicine, London, UK
| | - Susana Campino
- Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, UK.
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Singh OP, Kaur T, Sharma G, Kona MP, Mishra S, Kapoor N, Mallick PK. Molecular Tools for Early Detection of Invasive Malaria Vector Anopheles stephensi Mosquitoes. Emerg Infect Dis 2023; 29:36-44. [PMID: 36573521 PMCID: PMC9796203 DOI: 10.3201/eid2901.220786] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Reports of the expansion of the Asia malaria vector Anopheles stephensi mosquito into new geographic areas are increasing, which poses a threat to the elimination of urban malaria. Efficient surveillance of this vector in affected areas and early detection in new geographic areas is key to containing and controlling this species. To overcome the practical difficulties associated with the morphological identification of immature stages and adults of An. stephensi mosquitoes, we developed a species-specific PCR and a real-time PCR targeting a unique segment of the second internal transcribed spacer lacking homology to any other organism. Both PCRs can be used to identify An. stephensi mosquitoes individually or in pooled samples of mixed species, including when present in extremely low proportions (1:500). This study also reports a method for selective amplification and sequencing of partial ribosomal DNA from An. stephensi mosquitoes for their confirmation in pooled samples of mixed species.
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Multiple invasions, Wolbachia and human-aided transport drive the genetic variability of Aedes albopictus in the Iberian Peninsula. Sci Rep 2022; 12:20682. [PMID: 36450768 PMCID: PMC9712423 DOI: 10.1038/s41598-022-24963-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2022] [Accepted: 11/22/2022] [Indexed: 12/05/2022] Open
Abstract
The Asian tiger mosquito, Aedes albopictus, is one of the most invasive species in the world. Native to the tropical forests of Southeast Asia, over the past 30 years it has rapidly spread throughout tropical and temperate regions of the world. Its dramatic expansion has resulted in public health concerns as a consequence of its vector competence for at least 16 viruses. Previous studies showed that Ae. albopictus spread has been facilitated by human-mediated transportation, but much remains unknown about how this has affected its genetic attributes. Here we examined the factors that contributed to shaping the current genetic constitution of Ae. albopictus in the Iberian Peninsula, where the species was first found in 2004, by combining population genetics and Bayesian modelling. We found that both mitochondrial and nuclear DNA markers showed a lack of genetic structure and the presence of worldwide dominant haplotypes, suggesting regular introductions from abroad. Mitochondrial DNA showed little genetic diversity compared to nuclear DNA, likely explained by infection with maternally transmitted bacteria of the genus Wolbachia. Multilevel models revealed that greater mosquito fluxes (estimated from commuting patterns and tiger mosquito population distribution) and spatial proximity between sampling sites were associated with lower nuclear genetic distance, suggesting that rapid short- and medium-distance dispersal is facilitated by humans through vehicular traffic. This study highlights the significant role of human transportation in shaping the genetic attributes of Ae. albopictus and promoting regional gene flow, and underscores the need for a territorially integrated surveillance across scales of this disease-carrying mosquito.
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Dykes CL, Sharma G, Behera AK, Kapoor N, Paine MJI, Donnelly MJ, Singh OP. Tandem duplication of a genomic region encoding glutathione S-transferase epsilon-2 and -4 genes in DDT-resistant Anopheles stephensi strain from India. Sci Rep 2022; 12:17872. [PMID: 36284104 PMCID: PMC9596695 DOI: 10.1038/s41598-022-21522-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2022] [Accepted: 09/28/2022] [Indexed: 01/20/2023] Open
Abstract
The glutathione S-transferases (GST) genes are a multigene family of enzymes involved in the metabolism of endogenous and xenobiotic compounds by catalysing the conjugation of the reduced form of glutathione to the substrate. The epsilon class of GST (GSTe), unique to arthropods, is known to be involved in the detoxification process of several classes of insecticides, and GSTe2 in particular is known to have DDT dehydrochlorinase activity. This communication reports a tandem duplication of a genomic region encoding GSTe2 and GSTe4 genes in a laboratory-colonized DDT-resistant Anopheles stephensi. We identified duplication breakpoints and the organization of gene duplication through Sanger sequencing performed on long-PCR products. Manual annotation of sequences revealed a tandemly-arrayed duplication of a 3.62 kb segment of GST epsilon gene clusters comprised of five genes: a partial GSTe1, GSTe2, GSTe2-pseudogene, GSTe4 and partial GSTe5, interconnected by a conserved 2.42 kb DNA insert segment major part of which is homologous to a genomic region located on a different chromosome. The tandemly duplicated array contained a total of two GSTe2 and three GSTe4 functional paralog genes. Read-depth coverage and split-read analysis of Illumina-based whole-genome sequence reads confirmed the presence of duplication in the corresponding region of the genome. The increased gene dose in mosquitoes as a result of the GSTe gene-duplication may be an adaptive process to increase levels of detoxifying enzymes to counter insecticide pressure.
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Affiliation(s)
- Cherry L Dykes
- National Institute of Malaria Research, Sector 8, Dwarka, New Delhi, 110077, India
| | - Gunjan Sharma
- National Institute of Malaria Research, Sector 8, Dwarka, New Delhi, 110077, India
| | - Abhisek K Behera
- National Institute of Malaria Research, Sector 8, Dwarka, New Delhi, 110077, India
| | - Neera Kapoor
- Indira Gandhi National Open University, Maidangarhi, New Delhi, 110068, India
| | - Mark J I Paine
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, L3 5QA, UK
| | - Martin J Donnelly
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, L3 5QA, UK
| | - Om P Singh
- National Institute of Malaria Research, Sector 8, Dwarka, New Delhi, 110077, India.
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Singh OP, Mishra S, Sharma G, Sindhania A, Kaur T, Sreehari U, Das MK, Kapoor N, Gupta B. Evaluation of intron-1 of odorant-binding protein-1 of Anopheles stephensi as a marker for the identification of biological forms or putative sibling species. PLoS One 2022; 17:e0270760. [PMID: 35862377 PMCID: PMC9302840 DOI: 10.1371/journal.pone.0270760] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2022] [Accepted: 06/17/2022] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND Anopheles stephensi, an invasive malaria vector, has been reported to have three biological forms identifiable mainly based on the number of ridges present on the egg's floats. Recently, the first intron of the odorant-binding protein-1 (AsteObp1) has been introduced as a molecular marker for the identification of these forms, and based on this marker, the presence of three putative sibling species (designated as species A, B and C) has been proposed. However, there is no data on the association of proposed markers with biological form or putative species on field populations. METHODS Field collected and laboratory-reared An. stephensi were characterized for biological forms based on the number of ridges on the egg's float. DNA sequencing of the partial AsteObp1 gene of An. stephensi individuals were performed by Sanger's method, either directly or after cloning with a plasmid vector. Additionally, AsteObp1 sequences of various laboratory lines of An. stephensi were retrieved from a public sequence database. RESULTS AsteObp1 intron-1 in Indian An. stephensi populations are highly polymorphic with the presence of more than 13 haplotypes exhibiting nucleotides as well as length-polymorphism (90-to-121 bp). No specific haplotype or a group of closely related haplotypes of intron-1 was found associated with any biological form identified morphologically. High heterozygosity for this marker with a low inbreeding coefficient in field and laboratory populations indicates that this marker is not suitable for the delimitation of putative sibling species, at least in Indian populations. CONCLUSIONS AsteObp1 cannot serve as a marker for identifying biological forms of An. stephensi or putative sibling species in Indian populations.
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Affiliation(s)
- Om P. Singh
- National Institute of Malaria Research, Dwarka, New Delhi, India
- * E-mail: ,
| | - Shobhna Mishra
- National Institute of Malaria Research, Dwarka, New Delhi, India
| | - Gunjan Sharma
- National Institute of Malaria Research, Dwarka, New Delhi, India
| | - Ankita Sindhania
- National Institute of Malaria Research, Dwarka, New Delhi, India
| | - Taranjeet Kaur
- National Institute of Malaria Research, Dwarka, New Delhi, India
| | - U. Sreehari
- National Institute of Malaria Research, Field Unit, Bengaluru, India
| | - Manoj K. Das
- National Institute of Malaria Research, Field Unit, Ranchi, India
| | - Neera Kapoor
- School of Sciences, Indira Gandhi National Open University, Maidangarhi, New Delhi, India
| | - Bhavna Gupta
- Vector Control Research Centre, Field Station, Madurai, India
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Waymire E, Duddu S, Yared S, Getachew D, Dengela D, Bordenstein SR, Balkew M, Zohdy S, Irish SR, Carter TE. Wolbachia 16S rRNA haplotypes detected in wild Anopheles stephensi in eastern Ethiopia. Parasit Vectors 2022; 15:178. [PMID: 35610655 PMCID: PMC9128127 DOI: 10.1186/s13071-022-05293-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2021] [Accepted: 04/22/2022] [Indexed: 11/25/2022] Open
Abstract
BACKGROUND About two out of three Ethiopians are at risk of malaria, a disease caused by the parasites Plasmodium falciparum and Plasmodium vivax. Anopheles stephensi, an invasive vector typically found in South Asia and the Middle East, was recently found to be distributed across eastern and central Ethiopia and is capable of transmitting both P. falciparum and P. vivax. The detection of this vector in the Horn of Africa (HOA) coupled with widespread insecticide resistance requires that new methods of vector control be investigated in order to control the spread of malaria. Wolbachia, a naturally occurring endosymbiotic bacterium of mosquitoes, has been identified as a potential vector control tool that can be explored for the control of malaria transmission. Wolbachia could be used to control the mosquito population through suppression or potentially decrease malaria transmission through population replacement. However, the presence of Wolbachia in wild An. stephensi in eastern Ethiopia is unknown. This study aimed to identify the presence and diversity of Wolbachia in An. stephensi across eastern Ethiopia. METHODS DNA was extracted from An. stephensi collected from eastern Ethiopia in 2018 and screened for Wolbachia using a 16S targeted PCR assay, as well as multilocus strain typing (MLST) PCR assays. Haplotype and phylogenetic analysis of the sequenced 16S amplicons were conducted to compare with Wolbachia from countries across Africa and Asia. RESULTS Twenty out of the 184 mosquitoes screened were positive for Wolbachia, with multiple haplotypes detected. In addition, phylogenetic analysis revealed two superclades, representing Wolbachia supergroups A and B (bootstrap values of 81 and 72, respectively) with no significant grouping of geographic location or species. A subclade with a bootstrap value of 89 separates the Ethiopian haplotype 2 from other sequences in that superclade. CONCLUSIONS These findings provide the first evidence of natural Wolbachia populations in wild An. stephensi in the HOA. They also identify the need for further research to confirm the endosymbiotic relationship between Wolbachia and An. stephensi and to investigate its utility for malaria control in the HOA.
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Affiliation(s)
| | - Sowmya Duddu
- Department of Biology, Baylor University, Waco, TX USA
| | | | | | - Dereje Dengela
- PMI VectorLink Ethiopia Project, Abt Associates, Addis Ababa, Ethiopia
| | | | - Meshesha Balkew
- PMI VectorLink Ethiopia Project, Abt Associates, Addis Ababa, Ethiopia
| | - Sarah Zohdy
- U.S. President’s Malaria Initiative and Entomology Branch, Centers for Disease Control and Prevention, Atlanta, GA USA
| | - Seth R. Irish
- U.S. President’s Malaria Initiative and Entomology Branch, Centers for Disease Control and Prevention, Atlanta, GA USA
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Khan J, Gholizadeh S, Zhang D, Wang G, Guo Y, Zheng X, Wu Z, Wu Y. Identification of a biological form in the Anopheles stephensi laboratory colony using the odorant-binding protein 1 intron I sequence. PLoS One 2022; 17:e0263836. [PMID: 35192647 PMCID: PMC8863247 DOI: 10.1371/journal.pone.0263836] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2021] [Accepted: 01/27/2022] [Indexed: 11/18/2022] Open
Abstract
Background Anopheles stephensi Listen (1901) is a major vector of malaria in Asia and has recently been found in some regions of Africa. The An. stepehnsi species complex is suspected to have three sibling species: type, intermediate, and mysorensis, each with its own vector competence to the malaria parasite and ecology. To identify the members of the species complex in our An. stephensi insectary colony, we used the morphological features of eggs and genetic markers such as AnsteObp1 (Anopheles stephensi odorant binding protein 1), mitochondrial oxidases subunit 1 and 2 (COI and COII), and nuclear internal transcribed spacer 2 locus (ITS2). Methods Eggs were collected from individual mosquitoes (n = 50) and counted for the number of ridges under stereomicroscope. Genomic DNA was extracted from female mosquitoes. After the amplification of partial fragments of AnsteObp1, COI, COII and ITS2 genes, the PCR products were purified and sequenced. Phylogenetic analysis was performed after aligning query sequences against the submitted sequences in GenBank using MEGA 7. Results The range of ridges number on each egg float was 12–13 that corresponds to the mysorensis form of An. stephensi. The generated COI, COII and ITS2 sequences showed 100%, 99.46% and 99.29% similarity with the sequences deposited for Chinese, Indian and Iranian strains of An. stephensi, respectively. All the generated AnsteObp1 intron I region sequences matched 100% with the sequences deposited for An. stephensi sibling species C (mysorensis form) from Iran and Afghanistan. Conclusions This manuscript precisely describes the morphological and molecular details of the ‘var mysorensis’ form of An. stephensi that could be exploited in elucidating its classification as well as in differentiation from other biotypes of the same or other anopheline species. Based on our findings, we recommend AnsteObp1 as a robust genetic marker for rapid and accurate discrimination (taxonomic identification) of the An. stephensi species complex, rather than the COI, COII, and ITS2 marker, which could only be utilized for interspecies (Anopheles) differentiation.
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Affiliation(s)
- Jehangir Khan
- Department of Parasitology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, Guangdong, China
- Key Laboratory of Tropical Disease Control of the Ministry of Education, Zhongshan School of Medicine, Sun Yat-sen University-Michigan State University Joint Center of Vector Control for Tropical Disease, Guangzhou, Guangdong, China
- Department of Zoology, Abdul Wali Khan University Mardan, Khyber Pakhtunkhwa, Pakistan
- Chinese Atomic Energy Agency Center of Excellence on Nuclear Technology Applications for Insect Control, Sun Yat-sen University, Guangzhou, China
- * E-mail: (JK); (ZW); (YW)
| | - Saber Gholizadeh
- Cellular and Molecular Research Center, Cellular and Molecular Medicine Institute, Urmia University of Medical Sciences, Urmia, Iran
- Medical Entomology and Vector Control Department, School of Public Health, Urmia University of Medical Sciences, Urmia, Iran
| | - Dongjing Zhang
- Department of Parasitology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, Guangdong, China
- Key Laboratory of Tropical Disease Control of the Ministry of Education, Zhongshan School of Medicine, Sun Yat-sen University-Michigan State University Joint Center of Vector Control for Tropical Disease, Guangzhou, Guangdong, China
- Chinese Atomic Energy Agency Center of Excellence on Nuclear Technology Applications for Insect Control, Sun Yat-sen University, Guangzhou, China
| | - Gang Wang
- Department of Parasitology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, Guangdong, China
- Key Laboratory of Tropical Disease Control of the Ministry of Education, Zhongshan School of Medicine, Sun Yat-sen University-Michigan State University Joint Center of Vector Control for Tropical Disease, Guangzhou, Guangdong, China
- Chinese Atomic Energy Agency Center of Excellence on Nuclear Technology Applications for Insect Control, Sun Yat-sen University, Guangzhou, China
| | - Yan Guo
- Department of Parasitology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, Guangdong, China
- Key Laboratory of Tropical Disease Control of the Ministry of Education, Zhongshan School of Medicine, Sun Yat-sen University-Michigan State University Joint Center of Vector Control for Tropical Disease, Guangzhou, Guangdong, China
| | - Xiaoying Zheng
- Department of Parasitology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, Guangdong, China
- Key Laboratory of Tropical Disease Control of the Ministry of Education, Zhongshan School of Medicine, Sun Yat-sen University-Michigan State University Joint Center of Vector Control for Tropical Disease, Guangzhou, Guangdong, China
- Chinese Atomic Energy Agency Center of Excellence on Nuclear Technology Applications for Insect Control, Sun Yat-sen University, Guangzhou, China
| | - Zhongdao Wu
- Department of Parasitology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, Guangdong, China
- Key Laboratory of Tropical Disease Control of the Ministry of Education, Zhongshan School of Medicine, Sun Yat-sen University-Michigan State University Joint Center of Vector Control for Tropical Disease, Guangzhou, Guangdong, China
- Chinese Atomic Energy Agency Center of Excellence on Nuclear Technology Applications for Insect Control, Sun Yat-sen University, Guangzhou, China
- * E-mail: (JK); (ZW); (YW)
| | - Yu Wu
- Department of Parasitology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, Guangdong, China
- Key Laboratory of Tropical Disease Control of the Ministry of Education, Zhongshan School of Medicine, Sun Yat-sen University-Michigan State University Joint Center of Vector Control for Tropical Disease, Guangzhou, Guangdong, China
- Chinese Atomic Energy Agency Center of Excellence on Nuclear Technology Applications for Insect Control, Sun Yat-sen University, Guangzhou, China
- * E-mail: (JK); (ZW); (YW)
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Singh OP, Sindhania A, Sharma G, Mishra S, Sharma SK, Singh PK, Das MK. Are members of the Anopheles fluviatilis complex conspecific? Acta Trop 2021. [DOI: https://doi.org/10.1016/j.actatropica.2021.106149] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
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Singh OP, Sindhania A, Sharma G, Mishra S, Sharma SK, Singh PK, Das MK. Are members of the Anopheles fluviatilis complex conspecific? Acta Trop 2021. [DOI: https:/doi.org/10.1016/j.actatropica.2021.106149] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
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Singh OP, Sindhania A, Sharma G, Mishra S, Sharma SK, Singh PK, Das MK. Are members of the Anopheles fluviatilis complex conspecific? Acta Trop 2021; 224:106149. [PMID: 34599889 DOI: 10.1016/j.actatropica.2021.106149] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2021] [Revised: 09/16/2021] [Accepted: 09/16/2021] [Indexed: 02/05/2023]
Abstract
Anopheles fluviatilis sensu lato, a primary malaria vector in India, has been identified to be comprised of four cryptic species, provisionally designated as species S, T, U and V. However, Kumar et al. (Mol Ecol Resour, 2013;13:354-61) considered all of the then known three members of this species complex (S, T and U) conspecific. The specific status of species S and T was refuted based on the lack of sufficient barcode gap in mitochondrial-CO1 and the perceived presence of heterozygotes in populations as detected through one of the two species-specific PCR assays employed for the cryptic species identification. The existence of species U was refuted claiming that earlier investigations have already refuted their existence. Here we discuss problems associated with the CO1-based barcode approach for delimitation of cryptic species, the perceived heterozygosity between species S and T based on a species-specific PCR assay, and interpretation of published reports. We demonstrated that fixed differences do exist in the ITS2-rDNA sequence of species S and T with no evidence of heterozygotes in sympatric populations and, that the observed heterozygosity by Kumar et al. in the ITS2-based species diagnostic PCR is due to the high mispriming tendency of the T-specific primer with species S. We infer that mitochondrial DNA-based 'barcoding gap', an arbitrary threshold recommended for species delimitation, alone, is inadequate to delimit the members of An. fluviatilis complex.
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Affiliation(s)
- Om P Singh
- National Institute of Malaria Research, Sector 8, Dwarka, Delhi, 110077, India.
| | - Ankita Sindhania
- National Institute of Malaria Research, Sector 8, Dwarka, Delhi, 110077, India
| | - Gunjan Sharma
- National Institute of Malaria Research, Sector 8, Dwarka, Delhi, 110077, India
| | - Shobhna Mishra
- National Institute of Malaria Research, Sector 8, Dwarka, Delhi, 110077, India
| | - Surya K Sharma
- National Institute of Malaria Research, Field Unit, Sector-5, Rourkela 769 002, Orissa, India
| | - Piyoosh K Singh
- National Institute of Malaria Research, Field Unit, T. B. Sanitorium complex, Itki, Ranchi, 835301
| | - Manoj K Das
- National Institute of Malaria Research, Field Unit, T. B. Sanitorium complex, Itki, Ranchi, 835301
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