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Orubuloye OY, Mbewe NJ, Tchouassi DP, Yusuf AA, Pirk CWW, Torto B. An Overview of Tsetse Fly Repellents: Identification and Applications. J Chem Ecol 2024:10.1007/s10886-024-01527-5. [PMID: 38976099 DOI: 10.1007/s10886-024-01527-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2024] [Revised: 06/22/2024] [Accepted: 06/28/2024] [Indexed: 07/09/2024]
Abstract
Tsetse flies are vectors of the parasite trypanosoma that cause the neglected tropical diseases human and animal African trypanosomosis. Semiochemicals play important roles in the biology and ecology of tsetse flies. Previous reviews have focused on olfactory-based attractants of tsetse flies. Here, we present an overview of the identification of repellents and their development into control tools for tsetse flies. Both natural and synthetic repellents have been successfully tested in laboratory and field assays against specific tsetse fly species. Thus, these repellents presented as innovative mobile tools offer opportunities for their use in integrated disease management strategies.
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Affiliation(s)
- Olabimpe Y Orubuloye
- Department of Zoology and Entomology, University of Pretoria, Private Bag X20, Hatfield, 0028, Pretoria, South Africa.
| | - Njelembo J Mbewe
- Department of Zoology and Entomology, University of Pretoria, Private Bag X20, Hatfield, 0028, Pretoria, South Africa
- Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - David P Tchouassi
- International Centre of Insect Physiology and Ecology (icipe), P.O. Box 30772-00100, Nairobi, Kenya
| | - Abdullahi A Yusuf
- Department of Zoology and Entomology, University of Pretoria, Private Bag X20, Hatfield, 0028, Pretoria, South Africa
| | - Christian W W Pirk
- Department of Zoology and Entomology, University of Pretoria, Private Bag X20, Hatfield, 0028, Pretoria, South Africa
| | - Baldwyn Torto
- Department of Zoology and Entomology, University of Pretoria, Private Bag X20, Hatfield, 0028, Pretoria, South Africa
- International Centre of Insect Physiology and Ecology (icipe), P.O. Box 30772-00100, Nairobi, Kenya
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Ong'onge MA, Ajene IJ, Runo S, Sokame BM, Khamis FM. Population dynamics and insecticide resistance in Tuta absoluta (Lepidoptera: Gelechiidae), an invasive pest on tomato in Kenya. Heliyon 2023; 9:e21465. [PMID: 38027621 PMCID: PMC10660591 DOI: 10.1016/j.heliyon.2023.e21465] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2023] [Revised: 10/05/2023] [Accepted: 10/21/2023] [Indexed: 12/01/2023] Open
Abstract
Tuta absoluta feeds on solanaceous plants with preference on tomato. Management of the pest is mostly with chemical insecticides. This study identified insecticide resistant populations and predicted resistance to insecticides. Insecticide resistance development was modelled using system thinking, and system dynamics approaches. The model showed the pest resistance development is alarming with an exponential increase of the resistance strength mostly in recent years. Furthermore, we used seven insecticide-resistance gene markers to resolve the population structure and genetic differentiation of insecticide-resistant populations in Kenya. The genes for resistance (knockdown resistance (kdr) mutations, acetylcholinesterase (AChE) and voltage gated sodium channel (para)) were detected in all populations. Population structure analyses separated T. absoluta populations into three genetic clusters with resistant genes that are interconnected. A better insight on the population dynamics and the genetic structure T. absoluta resistant genes in Kenya will help estimate resistance strength and determine the most effective pest control strategies.
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Affiliation(s)
- Maureen Adhiambo Ong'onge
- International Centre of Insect Physiology and Ecology (icipe), Nairobi, Kenya
- Department of Biochemistry, Microbiology and Biotechnology, Kenyatta University, Nairobi, Kenya
| | - Inusa Jacob Ajene
- International Centre of Insect Physiology and Ecology (icipe), Nairobi, Kenya
| | - Steven Runo
- Department of Biochemistry, Microbiology and Biotechnology, Kenyatta University, Nairobi, Kenya
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Alonso DP, Alvarez MVN, Amorim JA, de Sá ILR, de Carvalho DP, Ribeiro KAN, Ribolla PEM, Sallum MAM. Mansonia spp. population genetics based on mitochondrion whole-genome sequencing alongside the Madeira River near Porto Velho, Rondonia, Brazil. INFECTION, GENETICS AND EVOLUTION : JOURNAL OF MOLECULAR EPIDEMIOLOGY AND EVOLUTIONARY GENETICS IN INFECTIOUS DISEASES 2022; 103:105341. [PMID: 35878819 DOI: 10.1016/j.meegid.2022.105341] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/25/2022] [Revised: 05/18/2022] [Accepted: 07/15/2022] [Indexed: 06/15/2023]
Abstract
In high abundance, females of the genus Mansonia (Blanchard) can be a nuisance to humans and animals because they are voraciously hematophagous and feed on the blood of a myriad of vertebrates. The spatial-temporal distribution pattern of Mansonia species is associated with the presence of their host plants, usually Eichhornia crassipes, E. azurea, Ceratopteris pteridoides, Limnobium laevigatum, Pistia stratiotes, and Salvinia sp. Despite their importance, there is a lack of investigation on the dispersion and population genetics of Mansonia species. Such studies are pivotal to evaluating the genetic structuring, which ultimately reflects populational expansion-retraction patterns and dispersal dynamics of the mosquito, particularly in areas with a history of recent introduction and establishment. The knowledge obtained could lead to better understanding of how anthropogenic changes to the environment can modulate the population structure of Mansonia species, which in turn impacts mosquito population density, disturbance to humans and domestic animals, and putative vector-borne disease transmission patterns. In this study, we present an Illumina NGS sequencing protocol to obtain whole-mitogenome sequences of Mansonia spp. to assess the microgeographic genetic diversity and dispersion of field-collected adults. The specimens were collected in rural environments in the vicinities of the Santo Antônio Energia (SAE) hydroelectric reservoir on the Madeira River.
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Affiliation(s)
- Diego Peres Alonso
- Sao Paulo State University, UNESP - Biotechnology Institute and Bioscience Institute, Botucatu 18618-689, Brazil; Departamento de Epidemiologia, Faculdade de Saúde Pública, Universidade de São Paulo, São Paulo, SP, Brazil.
| | - Marcus Vinicius Niz Alvarez
- Sao Paulo State University, UNESP - Biotechnology Institute and Bioscience Institute, Botucatu 18618-689, Brazil
| | - Jandui Almeida Amorim
- Departamento de Epidemiologia, Faculdade de Saúde Pública, Universidade de São Paulo, São Paulo, SP, Brazil
| | - Ivy Luizi Rodrigues de Sá
- Departamento de Epidemiologia, Faculdade de Saúde Pública, Universidade de São Paulo, São Paulo, SP, Brazil
| | | | | | | | - Maria Anice Mureb Sallum
- Departamento de Epidemiologia, Faculdade de Saúde Pública, Universidade de São Paulo, São Paulo, SP, Brazil
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Spatial Distribution of Tsetse Flies and Trypanosome Infection Status in a Vector Genetic Transition Zone in Northern Uganda. J Parasitol Res 2022; 2022:9142551. [PMID: 35692442 PMCID: PMC9177332 DOI: 10.1155/2022/9142551] [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: 03/07/2022] [Revised: 05/13/2022] [Accepted: 05/18/2022] [Indexed: 11/18/2022] Open
Abstract
Background Tsetse flies are vectors of the genus Trypanosoma that cause African trypanosomiasis, a serious parasitic disease of people and animals. Reliable data on the vector distribution and the trypanosome species they carry is pertinent for planning sustainable control strategies. This study was carried out to estimate the spatial distribution, apparent density, and trypanosome infection rates of tsetse flies in two districts that fall within a vector genetic transition zone in northern Uganda. Materials and Methods Capturing of tsetse flies was done using biconical traps deployed in eight villages in Oyam and Otuke, two districts that fall within the vector genetic transition zone in northern Uganda. Trapped tsetse flies were sexed and morphologically identified to species level and subsequently analyzed for detection of trypanosome DNA. Trypanosome DNA was detected using a nested PCR protocol based on primers amplifying the internal transcribed spacer (ITS) region of ribosomal DNA. Results A total of 717 flies (406 females; 311 males) were caught, all belonging to the Glossina fuscipes fuscipes species. The overall average flies/trap/day (FTD) was 2.20 ± 0.3527 (mean ± SE). Out of the 477 (201 male; 276 females) flies analyzed, 7.13% (34/477) were positive for one or more trypanosome species. Three species of bovine trypanosomes were detected, namely, Trypanosoma vivax, 61.76% (21/34), T. congolense, 26.47% (9/34), and T. brucei brucei, 5.88% (2/34), and two cases of mixed infection of T. congolense and T. brucei brucei, 5.88% (2/34). The infection rate was not significantly associated with the sex of the fly (generalized linear model (GLM), χ2 = 0.051, p = 0.821, df = 1, n = 477) and district of origin (χ2 = 0.611, p = 0.434, df = 1, n = 477). However, trypanosome infection was highly significantly associated with the fly's age based on wing fray category (χ2 = 7.56, p = 0.006, df = 1, n = 477), being higher among the very old than the young. Conclusion The relatively high tsetse density and trypanosome infection rate indicate that the transition zone is a high-risk area for perpetuating animal trypanosomiasis. Therefore, appropriate mitigation measures should be instituted targeting tsetse and other biting flies that may play a role as disease vectors, given the predominance of T. vivax in the tsetse samples.
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Maxamhud S, Lindahl JF, Mugenyi A, Echodu R, Waiswa C, Roesel K. Seasonal Monitoring of Glossina Species Occurrence, Infection Rates, and Trypanosoma Species Infections in Pigs in West Nile Region, Uganda. Vector Borne Zoonotic Dis 2022; 22:101-107. [PMID: 35175139 DOI: 10.1089/vbz.2020.2744] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Introduction: Trypanosomiasis is a parasitic infection caused by the protozoa Trypanosoma. It is exclusively associated with Glossina species habitats and, therefore, restricted to specific geographical settings. It affects a wide range of hosts, including humans. Animals may carry different Trypanosoma spp. while being asymptomatic. They are, therefore, potentially important in unpremeditated disease transmission. Aim: The aim of this study was to study the potential impact of the government tsetse fly control program, and to elucidate the role of pigs in the Trypanosoma epidemiology in the West Nile region in Uganda. Methods: A historically important human African trypanosomiasis (HAT) hotspot was selected, with sampling in sites with and without a government tsetse fly control program. Pigs were screened for infection with Trypanosoma and tsetse traps were deployed to monitor vector occurrence, followed by tsetse fly dissection and microscopy to establish infection rates with Trypanosoma. Pig blood samples were further analyzed to identify possible Trypanosoma infections using internal transcribed spacer (ITS)-PCR. Results: Using microscopy, Trypanosoma was detected in 0.56% (7/1262) of the sampled pigs. Using ITS-PCR, 114 of 341 (33.4%) pig samples were shown to be Trypanosoma vivax positive. Of the 360 dissected tsetse flies, 13 (3.8%) were positive for Trypanosoma under the microscope. The difference in captured tsetse flies in the government intervention sites in comparison with the control sites was significant (p < 0.05). Seasonality did not play a substantial role in the tsetse fly density (p > 0.05). Conclusion: This study illustrated the impact of a government control program with low vector abundance in a historical HAT hotspot in Uganda. The study could not verify that pigs in the area were carriers for the causative agent for HAT, but showed a high prevalence of the animal infectious agent T. vivax.
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Affiliation(s)
- Sadiya Maxamhud
- Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden
| | - Johanna F Lindahl
- Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden.,Department of Biosciences, International Livestock Research Institute, Nairobi, Kenya.,Department of Clinical Sciences, Swedish University of Agricultural Science, Uppsala, Sweden
| | - Albert Mugenyi
- Coordinating Office for Control of Trypanosomiasis in Uganda, Ministry of Agriculture, Animal Industry and Fisheries, Makerere, Uganda
| | - Richard Echodu
- Department of Biology, Faculty of Science, Gulu University, Gulu, Uganda
| | - Charles Waiswa
- Coordinating Office for Control of Trypanosomiasis in Uganda, Ministry of Agriculture, Animal Industry and Fisheries, Makerere, Uganda.,Department of Pharmacy, Clinical and Comparative Studies, School of Veterinary Medicine and Animal Resources, Makerere University, Kampala, Uganda
| | - Kristina Roesel
- Department of Biosciences, International Livestock Research Institute, Nairobi, Kenya.,Department of Veterinary Medicine, Institute for Parasitology and Tropical Veterinary Medicine, Freie Universität Berlin, Berlin, Germany
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Opiro R, Opoke R, Angwech H, Nakafu E, Oloya FA, Openy G, Njahira M, Macharia M, Echodu R, Malinga GM, Opiyo EA. Apparent density, trypanosome infection rates and host preference of tsetse flies in the sleeping sickness endemic focus of northwestern Uganda. BMC Vet Res 2021; 17:365. [PMID: 34839816 PMCID: PMC8628410 DOI: 10.1186/s12917-021-03071-w] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2020] [Accepted: 11/13/2021] [Indexed: 11/11/2022] Open
Abstract
Background African trypanosomiasis, caused by protozoa of the genus Trypanosoma and transmitted by the tsetse fly, is a serious parasitic disease of humans and animals. Reliable data on the vector distribution, feeding preference and the trypanosome species they carry is pertinent to planning sustainable control strategies. Methodology We deployed 109 biconical traps in 10 villages in two districts of northwestern Uganda to obtain information on the apparent density, trypanosome infection status and blood meal sources of tsetse flies. A subset (272) of the collected samples was analyzed for detection of trypanosomes species and sub-species using a nested PCR protocol based on primers amplifying the Internal Transcribed Spacer (ITS) region of ribosomal DNA. 34 blood-engorged adult tsetse midguts were analyzed for blood meal sources by sequencing of the mitochondrial cytochrome c oxidase 1 (COI) and cytochrome b (cytb) genes. Results We captured a total of 622 Glossina fuscipes fuscipes tsetse flies (269 males and 353 females) in the two districts with apparent density (AD) ranging from 0.6 to 3.7 flies/trap/day (FTD). 10.7% (29/272) of the flies were infected with one or more trypanosome species. Infection rate was not significantly associated with district of origin (Generalized linear model (GLM), χ2 = 0.018, P = 0.895, df = 1, n = 272) and sex of the fly (χ2 = 1.723, P = 0.189, df = 1, n = 272). However, trypanosome infection was highly significantly associated with the fly’s age based on wing fray category (χ2 = 22.374, P < 0.001, df = 1, n = 272), being higher among the very old than the young tsetse. Nested PCR revealed several species of trypanosomes: T. vivax (6.62%), T. congolense (2.57%), T. brucei and T. simiae each at 0.73%. Blood meal analyses revealed five principal vertebrate hosts, namely, cattle (Bos taurus), humans (Homo sapiens), Nile monitor lizard (Varanus niloticus), African mud turtle (Pelusios chapini) and the African Savanna elephant (Loxodonta africana). Conclusion We found an infection rate of 10.8% in the tsetse sampled, with all infections attributed to trypanosome species that are causative agents for AAT. However, more verification of this finding using large-scale passive and active screening of human and tsetse samples should be done. Cattle and humans appear to be the most important tsetse hosts in the region and should be considered in the design of control interventions.
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Affiliation(s)
- Robert Opiro
- Department of Biology, Faculty of Science, Gulu University, P.O Box 166, Gulu, Uganda.
| | - Robert Opoke
- Department of Biology, Faculty of Science, Muni University, P.O Box 725, Arua, Uganda
| | - Harriet Angwech
- Department of Biology, Faculty of Science, Gulu University, P.O Box 166, Gulu, Uganda
| | - Esther Nakafu
- Department of Molecular Biology, College of Veterinary Medicine, Animal Resources and Biosecurity, Makerere University, P.O Box 7062, Kampala, Uganda
| | - Francis A Oloya
- Department of Biology, Faculty of Science, Gulu University, P.O Box 166, Gulu, Uganda
| | - Geoffrey Openy
- Department of Biosystems Engineering, Faculty of Agriculture and Environment, Gulu University, P. O Box 166, Gulu, Uganda
| | - Moses Njahira
- Biosciences Eastern and Central Africa-International Livestock Research Institute Hub, P. O Box 30709, Nairobi, Kenya
| | - Mercy Macharia
- Biosciences Eastern and Central Africa-International Livestock Research Institute Hub, P. O Box 30709, Nairobi, Kenya
| | - Richard Echodu
- Department of Biology, Faculty of Science, Gulu University, P.O Box 166, Gulu, Uganda
| | - Geoffrey M Malinga
- Department of Biology, Faculty of Science, Gulu University, P.O Box 166, Gulu, Uganda.,Department of Forestry, Biodiversity and Tourism, Makerere University, PO Box 7062, Kampala, Uganda
| | - Elizabeth A Opiyo
- Department of Biology, Faculty of Science, Gulu University, P.O Box 166, Gulu, Uganda
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Kumar MS, Kalimuthu M, Selvam A, Mathivanan A, Paramasivan R, Kumar A, Gupta B. Genetic structure and connectivity among Aedes aegypti populations within Madurai city in Southern India. INFECTION GENETICS AND EVOLUTION 2021; 95:105031. [PMID: 34375746 DOI: 10.1016/j.meegid.2021.105031] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/11/2021] [Revised: 07/28/2021] [Accepted: 08/06/2021] [Indexed: 11/28/2022]
Abstract
We investigated the genetic variability and differentiation among 12 Ae. aegypti populations collected within the Madurai city in Tamil Nadu state of Southern India. Genotyping of 12 microsatellite markers in 353 individual samples showed moderate levels of genetic diversity among 12 populations. UPGMA tree, hierarchical clustering, Bayesian clustering and Discriminant Analysis on Principal Components roughly divided these populations into two genetic clusters: main city populations and the populations located at the border of the corporation limit. Significant positive correlation between genetic and geographic distance was observed among 12 populations, however, the correlation was non-significant within each genetic cluster. Population assignment and divMigrate graph depicted less migration between two groups. Overall, the findings of this study provided an overview of Ae. aegypti population structure within an urban setting in India that have implications in effective implementation of vector control in the city area.
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Affiliation(s)
- M Senthil Kumar
- ICMR-Vector Control Research Center, 4, Sarojini Street Chinna Chokkikulam, Madurai 625002, India
| | - M Kalimuthu
- ICMR-Vector Control Research Center, 4, Sarojini Street Chinna Chokkikulam, Madurai 625002, India
| | - A Selvam
- ICMR-Vector Control Research Center, 4, Sarojini Street Chinna Chokkikulam, Madurai 625002, India
| | - A Mathivanan
- ICMR-Vector Control Research Center, Medical Complex, Indira Nagar, 605006 Puducherry, India
| | - R Paramasivan
- ICMR-Vector Control Research Center, 4, Sarojini Street Chinna Chokkikulam, Madurai 625002, India
| | - Ashwani Kumar
- ICMR-Vector Control Research Center, Medical Complex, Indira Nagar, 605006 Puducherry, India
| | - Bhavna Gupta
- ICMR-Vector Control Research Center, 4, Sarojini Street Chinna Chokkikulam, Madurai 625002, India.
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Shin J, Jung J. Comparative population genetics of the invasive mosquito Aedes albopictus and the native mosquito Aedes flavopictus in the Korean peninsula. Parasit Vectors 2021; 14:377. [PMID: 34315478 PMCID: PMC8314453 DOI: 10.1186/s13071-021-04873-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2021] [Accepted: 07/07/2021] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Aedes mosquitoes are important invasive species contributing to the spread of chikungunya, dengue fever, yellow fever, zika virus, and other dangerous vector-borne diseases. Aedes albopictus is native to southeast Asia, with rapid expansion due to human activity, showing a wide distribution in the Korean peninsula. Aedes flavopictus is considered to be native to East Asia, with a broad distribution in the region, including the Korean peninsula. A better understanding of the genetic diversity of these species is critical for establishing strategies for disease prevention and vector control. METHODS We obtained DNA from 148 specimens of Ae. albopictus and 166 specimens of Ae. flavopictus in Korea, and amplified two mitochondrial genes (COI and ND5) to compare the genetic diversity and structure of the two species. RESULTS We obtained a 658-bp sequence of COI and a 423-bp sequence of ND5 from both mosquito species. We found low diversity and a nonsignificant population genetic structure in Ae. albopictus, and high diversity and a nonsignificant structure in Ae. flavopictus for these two mitochondrial genes. Aedes albopictus had fewer haplotypes with respect to the number of individuals, and a slight mismatch distribution was confirmed. By contrast, Ae. flavopictus had a large number of haplotypes compared with the number of individuals, and a large unimodal-type mismatch distribution was confirmed. Although the genetic structure of both species was nonsignificant, Ae. flavopictus exhibited higher genetic diversity than Ae. albopictus. CONCLUSIONS Aedes albopictus appears to be an introduced species, whereas Ae. flavopictus is endemic to the Korean peninsula, and the difference in genetic diversity between the two species is related to their adaptability and introduction history. Further studies on the genetic structure and diversity of these mosquitos will provide useful data for vector control.
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Affiliation(s)
- Jiyeong Shin
- The Division of EcoCreative, Ewha Womans University, Seoul, 03760 South Korea
| | - Jongwoo Jung
- The Division of EcoCreative, Ewha Womans University, Seoul, 03760 South Korea
- Department of Science Education, Ewha Womans University, Seoul, 03760 South Korea
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Bishop AP, Amatulli G, Hyseni C, Pless E, Bateta R, Okeyo WA, Mireji PO, Okoth S, Malele I, Murilla G, Aksoy S, Caccone A, Saarman NP. A machine learning approach to integrating genetic and ecological data in tsetse flies ( Glossina pallidipes) for spatially explicit vector control planning. Evol Appl 2021; 14:1762-1777. [PMID: 34295362 PMCID: PMC8288027 DOI: 10.1111/eva.13237] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2020] [Revised: 03/18/2021] [Accepted: 03/22/2021] [Indexed: 11/26/2022] Open
Abstract
Vector control is an effective strategy for reducing vector-borne disease transmission, but requires knowledge of vector habitat use and dispersal patterns. Our goal was to improve this knowledge for the tsetse species Glossina pallidipes, a vector of human and animal African trypanosomiasis, which are diseases that pose serious health and socioeconomic burdens across sub-Saharan Africa. We used random forest regression to (i) build and integrate models of G. pallidipes habitat suitability and genetic connectivity across Kenya and northern Tanzania and (ii) provide novel vector control recommendations. Inputs for the models included field survey records from 349 trap locations, genetic data from 11 microsatellite loci from 659 flies and 29 sampling sites, and remotely sensed environmental data. The suitability and connectivity models explained approximately 80% and 67% of the variance in the occurrence and genetic data and exhibited high accuracy based on cross-validation. The bivariate map showed that suitability and connectivity vary independently across the landscape and was used to inform our vector control recommendations. Post hoc analyses show spatial variation in the correlations between the most important environmental predictors from our models and each response variable (e.g., suitability and connectivity) as well as heterogeneity in expected future climatic change of these predictors. The bivariate map suggests that vector control is most likely to be successful in the Lake Victoria Basin and supports the previous recommendation that G. pallidipes from most of eastern Kenya should be managed as a single unit. We further recommend that future monitoring efforts should focus on tracking potential changes in vector presence and dispersal around the Serengeti and the Lake Victoria Basin based on projected local climatic shifts. The strong performance of the spatial models suggests potential for our integrative methodology to be used to understand future impacts of climate change in this and other vector systems.
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Affiliation(s)
- Anusha P. Bishop
- Department of Ecology and Evolutionary BiologyYale UniversityNew HavenCTUSA
- Department of Environmental Science, Policy, & ManagementUniversity of CaliforniaBerkeleyCAUSA
| | | | - Chaz Hyseni
- Department of Ecology and GeneticsUppsala UniversityUppsalaSweden
| | - Evlyn Pless
- Department of Ecology and Evolutionary BiologyYale UniversityNew HavenCTUSA
- Department of AnthropologyUniversity of CaliforniaDavisCAUSA
| | - Rosemary Bateta
- Biotechnology Research InstituteKenya Agricultural and Livestock Research OrganizationKikuyu, NairobiKenya
| | - Winnie A. Okeyo
- Biotechnology Research InstituteKenya Agricultural and Livestock Research OrganizationKikuyu, NairobiKenya
- Department of Biomedical Sciences and TechnologySchool of Public Health and Community DevelopmentMaseno UniversityMaseno, KisumuKenya
| | - Paul O. Mireji
- Biotechnology Research InstituteKenya Agricultural and Livestock Research OrganizationKikuyu, NairobiKenya
- Centre for Geographic Medicine Research CoastKenya Medical Research InstituteKilifiKenya
| | - Sylvance Okoth
- Biotechnology Research InstituteKenya Agricultural and Livestock Research OrganizationKikuyu, NairobiKenya
| | - Imna Malele
- Vector and Vector Borne Diseases Research InstituteTanzania Veterinary Laboratory AgencyTangaTanzania
| | - Grace Murilla
- Biotechnology Research InstituteKenya Agricultural and Livestock Research OrganizationKikuyu, NairobiKenya
| | - Serap Aksoy
- Department of Epidemiology of Microbial DiseasesYale School of Public HealthNew HavenCTUSA
| | - Adalgisa Caccone
- Department of Ecology and Evolutionary BiologyYale UniversityNew HavenCTUSA
| | - Norah P. Saarman
- Department of Ecology and Evolutionary BiologyYale UniversityNew HavenCTUSA
- Department of BiologyUtah State UniversityLoganUTUSA
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Hargrove JW, Van Sickle J, Vale GA, Lucas ER. Negative density-dependent dispersal in tsetse (Glossina spp): An artefact of inappropriate analysis. PLoS Negl Trop Dis 2021; 15:e0009026. [PMID: 33764969 PMCID: PMC8023489 DOI: 10.1371/journal.pntd.0009026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2020] [Revised: 04/06/2021] [Accepted: 02/24/2021] [Indexed: 11/18/2022] Open
Abstract
Published analysis of genetic material from field-collected tsetse (Glossina spp, primarily from the Palpalis group) has been used to predict that the distance (δ) dispersed per generation increases as effective population densities (De) decrease, displaying negative density-dependent dispersal (NDDD). Using the published data we show this result is an artefact arising primarily from errors in estimates of S, the area occupied by a subpopulation, and thereby in De. The errors arise from the assumption that S can be estimated as the area ( S^) regarded as being covered by traps. We use modelling to show that such errors result in anomalously high correlations between δ^ and S^ and the appearance of NDDD, with a slope of -0.5 for the regressions of log( δ^) on log( D^e), even in simulations where we specifically assume density-independent dispersal (DID). A complementary mathematical analysis confirms our findings. Modelling of field results shows, similarly, that the false signal of NDDD can be produced by varying trap deployment patterns. Errors in the estimates of δ in the published analysis were magnified because variation in estimates of S were greater than for all other variables measured, and accounted for the greatest proportion of variation in δ^. Errors in census population estimates result from an erroneous understanding of the relationship between trap placement and expected tsetse catch, exacerbated through failure to adjust for variations in trapping intensity, trap performance, and in capture probabilities between geographical situations and between tsetse species. Claims of support in the literature for NDDD are spurious. There is no suggested explanation for how NDDD might have evolved. We reject the NDDD hypothesis and caution that the idea should not be allowed to influence policy on tsetse and trypanosomiasis control. Published analysis of genetic material from field-sampled tsetse (Glossina spp) has been used to suggest that, as tsetse population densities decrease, rates of dispersal increase–displaying negative density-dependent dispersal (NDDD), perhaps in all tsetse species. It is further suggested that tsetse control operations might, as a consequence of NDDD, unleash enhanced invasion of areas cleared of tsetse, prejudicing the long-term success of control campaigns. We demonstrate that NDDD in tsetse is an artefact consequent on multiple errors of analysis and interpretation. The most serious of these errors stems from a misunderstanding of the way in which traps sample tsetse, resulting in large errors in estimates of the areas covered by the traps, and occupied by the subpopulations being sampled. Our modelling studies show that these errors can produce the false signal of NDDD, even in situations where DID is assumed. Errors in census population estimates are made worse through failure to adjust for variations in trapping intensity, trap performance, and in capture probabilities between geographical situations, and between tsetse species. We reject the NDDD hypothesis and caution that the idea should not be allowed to influence policy on tsetse and trypanosomiasis control.
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Affiliation(s)
- John W. Hargrove
- SACEMA, University of Stellenbosch, Stellenbosch, South Africa
- * E-mail:
| | - John Van Sickle
- Department of Fisheries and Wildlife, Oregon State University, Corvallis, Oregon, United States of America
| | - Glyn A. Vale
- SACEMA, University of Stellenbosch, Stellenbosch, South Africa
- Natural Resources Institute, University of Greenwich, Chatham, United Kingdom
| | - Eric R. Lucas
- Liverpool School of Tropical Medicine, Liverpool, United Kingdom
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Hargrove JW, Vale GA. Negative density-dependent dispersal in tsetse (Glossina spp): red flag or red herring? MEDICAL AND VETERINARY ENTOMOLOGY 2021; 35:30-41. [PMID: 32757252 DOI: 10.1111/mve.12466] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/25/2020] [Revised: 06/21/2020] [Accepted: 07/01/2020] [Indexed: 06/11/2023]
Abstract
A deterministic model of the distribution of tsetse flies (Glossina spp) was used to assess the extent to which the efficacy of control operations would be affected by three different modes of density dependence in per capita adult dispersal: (i) density-independent dispersal which has been commonly adopted in previous models, (ii) positive density-dependent dispersal which has occasionally been discussed in the tsetse literature, (iii) negative density-dependent dispersal (NDDD). The last has recently been suggested, from genetic studies, to change the dispersal rate of tsetse by up to 200-fold, thereby posing a severe risk for the success of tsetse control operations. Modelling outputs showed that NDDD poses no such risk, provided the mean daily dispersal of tsetse is below about 1 km, which is greater than any rate actually recorded in the field or indicated by the genetic studies. NDDD can be problematic only if tsetse disperse at rates that appear highly unlikely, or even impossible, on energetic grounds. Under some circumstances these high rates would help rather than hinder the control officer. NDDD is not necessary to explain the results of control operations, and not sufficient to explain the results of successful control programmes.
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Affiliation(s)
- J W Hargrove
- SACEMA, University of Stellenbosch, Stellenbosch, South Africa
| | - G A Vale
- SACEMA, University of Stellenbosch, Stellenbosch, South Africa
- Natural Resources Institute, University of Greenwich, Chatham, U.K
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Odeniran PO, Macleod ET, Ademola IO, Ohiolei JA, Majekodunmi AO, Welburn SC. Morphological, Molecular Identification and Distribution of Trypanosome-Transmitting Dipterans from Cattle Settlements in Southwest Nigeria. Acta Parasitol 2021; 66:116-128. [PMID: 32780296 DOI: 10.1007/s11686-020-00260-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2020] [Accepted: 07/28/2020] [Indexed: 10/22/2022]
Abstract
INTRODUCTION Glossina spp. (Glossinidae), Tabanus spp. (Tabanidae), Ancala spp. (Tabanidae), Atylotus spp. (Tabanidae) and Stomoxys spp. (Muscidae) are important transmitting vectors of African animal trypanosomosis in sub-Saharan Africa. There is paucity of information on the distribution and identification of these flies in cattle settlements in southwest Nigeria. METHODS The distribution patterns, genetic variations and diversities of dipteran flies in southwest Nigeria were described and identified using morphological and molecular analysis of the 28S rDNA gene. RESULTS Of the 13,895 flies examined morphologically between April 2016 and March 2017, tabanids were identified [Tabanus (0.34%), Ancala (0.03%), Atylotus (0.01%), Haematopota (0.014%) and Chrysops (0.11%)]. Two stomoxyine species were identified; Stomoxys niger niger Macquart (45.30%) and Stomoxys calcitrans Linnaeus (17.29%) and two Glossina spp. namely; Glossina p. gambiense Vanderplank, 1911 (0.46%) and Glossina tachinoides Westwood (0.51%) were identified. The identities were further confirmed in a BLAST search using their nucleotide sequences. The median-joining network of the 28S rDNA gene sequences indicated that fly species examined were genetically distinct. The apparent density of all the trapped flies was highest at a mean temperature of 26-28 ℃, humidity > 80% and rainfall of 150-220 mm/month. The distribution of flies was observed to increase as vegetation increased in density and decreased in areas with relatively high human population density (> 100/km2). CONCLUSIONS The population indices of the 28S rDNA gene of the flies suggest that analysis of nuclear DNA fragments may provide more information on the molecular ecology of these flies. Characterising fly species and assessing their impact are essential in distribution and monitoring AAT spread.
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Olaide OY, Tchouassi DP, Yusuf AA, Pirk CW, Masiga DK, Saini RK, Torto B. Effect of zebra skin-derived compounds on field catches of the human African trypanosomiasis vector Glossina fuscipes fuscipes. Acta Trop 2021; 213:105745. [PMID: 33160957 DOI: 10.1016/j.actatropica.2020.105745] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2020] [Revised: 10/21/2020] [Accepted: 10/23/2020] [Indexed: 10/23/2022]
Abstract
The riverine tsetse fly Glossina fuscipes fuscipes is a major vector of trypanosome pathogens causing African trypanosomiasis. This fly species uses a combination of olfactory and visual cues to locate its hosts. Previously, traps and targets baited with visual cues have been used in vector control, but the development of olfactory-based tools has been challenging. Recently, repellents have shown promise as olfactory-based tools in tsetse vector control. Here, we evaluated a three-component blend comprising 6-methyl-5-hepten-2-one, acetophenone and geranyl acetone (blend K), previously identified as a repellent for savannah tsetse flies in zebra skin odor, on G. f. fuscipes populations. Using a series of 6 × 6 randomized Latin square-designed experiments, G. f. fuscipes catches in biconical traps were monitored on four islands of Lake Victoria in western Kenya between July and September 2019, after the long rainy season. Traps were baited with blend K and individual components of this blend. The known tsetse repellent blend WRC (waterbuck repellent compounds) and trap alone were included as controls. Daily catch data in thirty-six replicate trials were analyzed using generalized linear model with negative binomial error structure using the package "MASS" in R. Treatment, day and site were set as predictor variables. Our results showed that, blend K significantly reduced G. f. fuscipes catches by 25.6% (P < 0.01) compared to the control trap alone but was not significantly different from WRC which reduced catches by 20.7% (P < 0.05). Of the individual compounds, geranyl acetone solely significantly reduced catches by 29.1% (P < 0.01) which did not differ from blend K or WRC. We conclude that geranyl acetone accounts for the repellent effect of blend K on the riverine tsetse fly, G. f. fuscipes, demonstrating the ecological importance of animal skin odors in the host-seeking behavior of medically-important tsetse fly vectors.
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Mayoke A, Ouma JO, Mireji PO, Omondi SF, Muya SM, Itoua A, Okoth SO, Bateta R. Population Structure and Migration Patterns of the Tsetse Fly Glossina fuscipes in Congo-Brazzaville. Am J Trop Med Hyg 2020; 104:917-927. [PMID: 33372648 PMCID: PMC7941806 DOI: 10.4269/ajtmh.20-0774] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Accepted: 11/17/2020] [Indexed: 11/07/2022] Open
Abstract
Tsetse flies of the palpalis group, particularly Glossina fuscipes, are the main vectors of human African trypanosomiasis or sleeping sickness in Congo-Brazzaville. They transmit the deadly human parasite, Trypanosoma brucei gambiense and other trypanosomes that cause animal trypanosomiasis. Knowledge on diversity, population structure, population size, and gene flow is a prerequisite for designing effective tsetse control strategies. There is limited published information on these parameters including migration patterns of G. fuscipes in Congo-Brazzaville. We genotyped 288 samples of G. fuscipes from Bomassa (BMSA), Bouemba (BEMB), and Talangai (TLG) locations at 10 microsatellite loci and determined levels of genetic diversity, differentiation, structuring, and gene flow among populations. We observed high genetic diversity in all three localities. Mean expected heterozygosity was 0.77 ± 0.04, and mean allelic richness was 11.2 ± 1.35. Deficiency of heterozygosity was observed in all populations with positive and significant F IS values (0.077-0.149). Structure analysis revealed three clusters with genetic admixtures, evidence of closely related but potentially different taxa within G. fuscipes. Genetic differentiation indices were low but significant (F ST = 0.049, P < 0.05), indicating ongoing gene flow countered with a stronger force of drift. We recorded significant migration from all the three populations, suggesting exchange of genetic information between and among locations. Ne estimates revealed high and infinite population sizes in BEMB and TLG. These critical factors should be considered when planning area-wide tsetse control interventions in the country to prevent resurgence of tsetse from relict populations and/or reinvasion of cleared habitats.
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Affiliation(s)
- Abraham Mayoke
- Department of Molecular Biology and Biotechnology, Pan African University Institute for Basic Sciences, Technology and Innovation, Nairobi, Kenya
- Kenya Forestry Research Institute, Nairobi, Kenya
- Biotechnology Research Institute, Kenya Agricultural and Livestock Research Organization, Kikuyu, Kenya
- Marien Ngouabi University, Brazzaville, Congo
| | - Johnson O. Ouma
- African Technical Research Centre, Vector Health International, Arusha, Tanzania
| | - Paul O. Mireji
- Biotechnology Research Institute, Kenya Agricultural and Livestock Research Organization, Kikuyu, Kenya
| | | | - Shadrack M. Muya
- School of Biological Sciences, Jomo Kenyatta University of Agriculture and Technology, Nairobi, Kenya
| | - Andre Itoua
- Laboratoire de Parasitologie, Centre de Recherche Veterinaire et Zootechniques, Brazzaville, Congo
| | - Sylvance O. Okoth
- Biotechnology Research Institute, Kenya Agricultural and Livestock Research Organization, Kikuyu, Kenya
| | - Rosemary Bateta
- Biotechnology Research Institute, Kenya Agricultural and Livestock Research Organization, Kikuyu, Kenya
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Mayoke A, Muya SM, Bateta R, Mireji PO, Okoth SO, Onyoyo SG, Auma JE, Ouma JO. Genetic diversity and phylogenetic relationships of tsetse flies of the palpalis group in Congo Brazzaville based on mitochondrial cox1 gene sequences. Parasit Vectors 2020; 13:253. [PMID: 32410644 PMCID: PMC7227191 DOI: 10.1186/s13071-020-04120-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2019] [Accepted: 05/06/2020] [Indexed: 01/20/2023] Open
Abstract
BACKGROUND Despite the morphological characterization established in the 1950s and 1960s, the identity of extant taxa that make up Glossina fuscipes (s.l.) in the Congo remains questionable. Previous claims of overlap between G. fuscipes (believed to be G. f. quanzensis) and G. palpalis palpalis around Brazzaville city further complicate the taxonomic status and population dynamics of the two taxa. This study aimed to determine the phylogenetic relationships between G. fuscipes (s.l.) and G. p. palpalis and to assess genetic variation among G. fuscipes (s.l.) populations in Congo Brazzaville. METHODS We collected 263 G. fuscipes (s.l.) from northern and central regions, and 65 G. p. palpalis from southern part of the country. The mitochondrial cytochrome c oxidase subunit 1 (cox1) gene was amplified using taxa-specific primer pairs. Sequence data were analyzed in DnaSP and Arlequin to assess the genetic diversity, differentiation and demographic history of G. fuscipes (s.l.) populations. RESULTS The general BLAST analysis yielded a similarity of 99% for G. fuscipes (s.l.) and G. p. palpalis. BLASTn analysis for G. fuscipes (s.l.) showed > 98% identity with GenBank sequences for G. fuscipes (s.l.), with BEMB population showing 100% similarity with G. f. fuscipes. Glossina fuscipes (s.l.) populations showed high haplotype diversity (H = 46, Hd = 0.884), moderate nucleotide diversity ( = 0.012) and moderate (FST = 0.072) to high (FST = 0.152) genetic differentiation. Most of the genetic variation (89.73%) was maintained within populations. The mismatch analysis and neutrality tests indicated recent tsetse population expansions. CONCLUSIONS Phylogenetic analysis revealed minor differences between G. fuscipes (s.l.) and G. p. palpalis. Genetic diversity of G. fuscipes (s.l.) was high in the populations sampled except one. Genetic differentiation ranged from moderate to high among subpopulations. There was a restricted gene flow between G. fuscipes (s.l.) populations in the north and central part of the country. Genetic signatures based on cox1 showed recent expansion and recovery of G. fuscipes (s.l.) populations from previous bottlenecks. To fully understand the species distribution limits, we recommend further studies involving a wider sampling scheme including the swampy Mossaka focus for G. fuscipes (s.l.) and the entire range of G. p. palpalis in South Congo.
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Affiliation(s)
- Abraham Mayoke
- Department of Molecular Biology and Biotechnology, Pan African University Institute for Basic Sciences, Technology & Innovation, PO Box 62000-00200, Nairobi, Kenya
- Kenya Agricultural and Livestock Research Organization, Biotechnology Research Institute, PO Box 362-00902, Kikuyu, Kenya
| | - Shadrack M. Muya
- Jomo Kenyatta University of Agriculture and Technology, Faculty of Biological Sciences, PO Box 62000-00200, Nairobi, Kenya
| | - Rosemary Bateta
- Kenya Agricultural and Livestock Research Organization, Biotechnology Research Institute, PO Box 362-00902, Kikuyu, Kenya
| | - Paul O. Mireji
- Kenya Agricultural and Livestock Research Organization, Biotechnology Research Institute, PO Box 362-00902, Kikuyu, Kenya
| | - Sylvance O. Okoth
- Kenya Agricultural and Livestock Research Organization, Biotechnology Research Institute, PO Box 362-00902, Kikuyu, Kenya
| | - Samuel G. Onyoyo
- Kenya Agricultural and Livestock Research Organization, Biotechnology Research Institute, PO Box 362-00902, Kikuyu, Kenya
| | - Joanna E. Auma
- Kenya Agricultural and Livestock Research Organization, Biotechnology Research Institute, PO Box 362-00902, Kikuyu, Kenya
| | - Johnson O. Ouma
- African Technical Research Centre, Vector Health International, P.O. Box 15500, Arusha, Tanzania
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Ndeffo-Mbah ML, Pandey A, Atkins KE, Aksoy S, Galvani AP. The impact of vector migration on the effectiveness of strategies to control gambiense human African trypanosomiasis. PLoS Negl Trop Dis 2019; 13:e0007903. [PMID: 31805051 PMCID: PMC6894748 DOI: 10.1371/journal.pntd.0007903] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2019] [Accepted: 11/04/2019] [Indexed: 02/06/2023] Open
Abstract
Background Several modeling studies have been undertaken to assess the feasibility of the WHO goal of eliminating gambiense human African trypanosomiasis (g-HAT) by 2030. However, these studies have generally overlooked the effect of vector migration on disease transmission and control. Here, we evaluated the impact of vector migration on the feasibility of interrupting transmission in different g-HAT foci. Methods We developed a g-HAT transmission model of a single tsetse population cluster that accounts for migration of tsetse fly into this population. We used a model calibration approach to constrain g-HAT incidence to ranges expected for high, moderate and low transmission settings, respectively. We used the model to evaluate the effectiveness of current intervention measures, including medical intervention through enhanced screening and treatment, and vector control, for interrupting g-HAT transmission in disease foci under each transmission setting. Results We showed that, in low transmission settings, under enhanced medical intervention alone, at least 70% treatment coverage is needed to interrupt g-HAT transmission within 10 years. In moderate transmission settings, a combination of medical intervention and a vector control measure with a daily tsetse mortality greater than 0.03 is required to achieve interruption of disease transmission within 10 years. In high transmission settings, interruption of disease transmission within 10 years requires a combination of at least 70% medical intervention coverage and at least 0.05 tsetse daily mortality rate from vector control. However, the probability of achieving elimination in high transmission settings decreases with an increased tsetse migration rate. Conclusion Our results suggest that the WHO 2030 goal of G-HAT elimination is, at least in theory, achievable. But the presence of tsetse migration may reduce the probability of interrupting g-HAT transmission in moderate and high transmission foci. Therefore, optimal vector control programs should incorporate monitoring and controlling of vector density in buffer areas around foci of g-HAT control efforts. Gambian human African trypanosomiasis (g-HAT), also known as sleeping sickness, is a vector-borne parasitic disease transmitted by tsetse flies. If untreated, g-HAT infection will usually result in death. Recently, the World Health Organization (WHO) has targeted g-HAT for elimination through achieving interruption of transmission by 2030. To help inform elimination efforts, mathematical models have been used to evaluate the feasibility of the WHO goals in different g-HAT transmission foci. However, these mathematical models have generally ignored the role that tsetse migration may have in the spread and reemergence of g-HAT. Using a mathematical model, we evaluate the impact of tsetse migration on the effectiveness of current intervention measures for achieving interruption of g-HAT transmission in different transmission foci. We consider different interventions such as enhanced screening and treatment and vector control. We show that vector control has a great potential for reducing transmission. Still, the presence and intensity of tsetse migration can undermine its effectiveness for interrupting disease transmission, especially in high transmission foci. Our results indicate the need of accounting for tsetse surveillance and migration data in designing vector control efforts for g-HAT elimination.
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Affiliation(s)
- Martial L. Ndeffo-Mbah
- Department of Veterinary Integrative Biosciences, Texas A&M College of Veterinary Medicine and Biomedical Sciences, College Station, TX, United States of America
- Department of Epidemiology and Biostatistics, Texas A&M School of Public Health, College Station, TX, United States of America
- * E-mail:
| | - Abhishek Pandey
- Center for Infectious Disease Modeling and Analysis, Yale School of Public Health, New Haven, CT, United States of America
- Department of Epidemiology and Microbial Diseases, Yale School of Public Health, New Haven, CT, United States of America
| | - Katherine E. Atkins
- Department of Infectious Disease Epidemiology, Faculty of Epidemiology and Population Health, London School of Hygiene and Tropical Medicine, London, United Kingdom
- Centre for Mathematical Modelling of Infectious Diseases, London School of Hygiene and Tropical Medicine, London, United Kingdom
- Centre for Global Health, The Usher Institute for Population Health Sciences and Informatics, Edinburgh Medical School, The University of Edinburgh, Edinburgh, United Kingdom
| | - Serap Aksoy
- Department of Epidemiology and Microbial Diseases, Yale School of Public Health, New Haven, CT, United States of America
| | - Alison P. Galvani
- Center for Infectious Disease Modeling and Analysis, Yale School of Public Health, New Haven, CT, United States of America
- Department of Epidemiology and Microbial Diseases, Yale School of Public Health, New Haven, CT, United States of America
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Saarman NP, Opiro R, Hyseni C, Echodu R, Opiyo EA, Dion K, Johnson T, Aksoy S, Caccone A. The population genomics of multiple tsetse fly (Glossina fuscipes fuscipes) admixture zones in Uganda. Mol Ecol 2019; 28:66-85. [PMID: 30471158 DOI: 10.1111/mec.14957] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2018] [Revised: 10/26/2018] [Accepted: 11/05/2018] [Indexed: 11/28/2022]
Abstract
Understanding the mechanisms that enforce, maintain or reverse the process of speciation is an important challenge in evolutionary biology. This study investigates the patterns of divergence and discusses the processes that form and maintain divergent lineages of the tsetse fly Glossina fuscipes fuscipes in Uganda. We sampled 251 flies from 18 sites spanning known genetic lineages and the four admixture zones between them. We apply population genomics, hybrid zone and approximate Bayesian computation to the analysis of three types of genetic markers: 55,267 double-digest restriction site-associated DNA (ddRAD) SNPs to assess genome-wide admixture, 16 microsatellites to provide continuity with published data and accurate biogeographic modelling, and a 491-bp fragment of mitochondrial cytochrome oxidase I and II to infer maternal inheritance patterns. Admixture zones correspond with regions impacted by the reorganization of Uganda's river networks that occurred during the formation of the West African Rift system over the last several hundred thousand years. Because tsetse fly population distributions are defined by rivers, admixture zones likely represent both old and new regions of secondary contact. Our results indicate that older hybrid zones contain mostly parental types, while younger zones contain variable hybrid types resulting from multiple generations of interbreeding. These findings suggest that reproductive barriers are nearly complete in the older admixture zones, while nearly absent in the younger admixture zones. Findings are consistent with predictions of hybrid zone theory: Populations in zones of secondary contact transition rapidly from early to late stages of speciation or collapse all together.
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Affiliation(s)
- Norah P Saarman
- Department of Ecology and Evolutionary Biology, Yale University, New Haven, Connecticut
| | - Robert Opiro
- Department of Biology, Faculty of Science, Gulu University, Uganda
| | - Chaz Hyseni
- Department of Biology, University of Mississippi, Oxford, Mississippi
| | - Richard Echodu
- Department of Biology, Faculty of Science, Gulu University, Uganda
| | | | - Kirstin Dion
- Department of Ecology and Evolutionary Biology, Yale University, New Haven, Connecticut
| | - Thomas Johnson
- Department of Ecology and Evolutionary Biology, Yale University, New Haven, Connecticut
| | - Serap Aksoy
- Department of Epidemiology of Microbial Diseases, Yale School of Public Health, New Haven, Connecticut
| | - Adalgisa Caccone
- Department of Ecology and Evolutionary Biology, Yale University, New Haven, Connecticut
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Schneider DI, Saarman N, Onyango MG, Hyseni C, Opiro R, Echodu R, O’Neill M, Bloch D, Vigneron A, Johnson TJ, Dion K, Weiss BL, Opiyo E, Caccone A, Aksoy S. Spatio-temporal distribution of Spiroplasma infections in the tsetse fly (Glossina fuscipes fuscipes) in northern Uganda. PLoS Negl Trop Dis 2019; 13:e0007340. [PMID: 31369548 PMCID: PMC6692048 DOI: 10.1371/journal.pntd.0007340] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2019] [Revised: 08/13/2019] [Accepted: 07/13/2019] [Indexed: 12/13/2022] Open
Abstract
Tsetse flies (Glossina spp.) are vectors of parasitic trypanosomes, which cause human (HAT) and animal African trypanosomiasis (AAT) in sub-Saharan Africa. In Uganda, Glossina fuscipes fuscipes (Gff) is the main vector of HAT, where it transmits Gambiense disease in the northwest and Rhodesiense disease in central, southeast and western regions. Endosymbionts can influence transmission efficiency of parasites through their insect vectors via conferring a protective effect against the parasite. It is known that the bacterium Spiroplasma is capable of protecting its Drosophila host from infection with a parasitic nematode. This endosymbiont can also impact its host's population structure via altering host reproductive traits. Here, we used field collections across 26 different Gff sampling sites in northern and western Uganda to investigate the association of Spiroplasma with geographic origin, seasonal conditions, Gff genetic background and sex, and trypanosome infection status. We also investigated the influence of Spiroplasma on Gff vector competence to trypanosome infections under laboratory conditions. Generalized linear models (GLM) showed that Spiroplasma probability was correlated with the geographic origin of Gff host and with the season of collection, with higher prevalence found in flies within the Albert Nile (0.42 vs 0.16) and Achwa River (0.36 vs 0.08) watersheds and with higher prevalence detected in flies collected in the intermediate than wet season. In contrast, there was no significant correlation of Spiroplasma prevalence with Gff host genetic background or sex once geographic origin was accounted for in generalized linear models. Additionally, we found a potential negative correlation of Spiroplasma with trypanosome infection, with only 2% of Spiroplasma infected flies harboring trypanosome co-infections. We also found that in a laboratory line of Gff, parasitic trypanosomes are less likely to colonize the midgut in individuals that harbor Spiroplasma infection. These results indicate that Spiroplasma infections in tsetse may be maintained by not only maternal but also via horizontal transmission routes, and Spiroplasma infections may also have important effects on trypanosome transmission efficiency of the host tsetse. Potential functional effects of Spiroplasma infection in Gff could have impacts on vector control approaches to reduce trypanosome infections.
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Affiliation(s)
- Daniela I. Schneider
- Department of Epidemiology of Microbial Diseases, Yale School of Public Health, New Haven, CT, United States of America
- * E-mail:
| | - Norah Saarman
- Department of Ecology and Evolutionary Biology, Yale University, New Haven, CT, United States of America
| | - Maria G. Onyango
- Department of Epidemiology of Microbial Diseases, Yale School of Public Health, New Haven, CT, United States of America
| | - Chaz Hyseni
- Department of Biology, University of Mississippi, University, MS, United States of America
| | - Robert Opiro
- Department of Biology, Faculty of Science, Gulu University, Uganda
| | - Richard Echodu
- Department of Biology, Faculty of Science, Gulu University, Uganda
| | - Michelle O’Neill
- Department of Epidemiology of Microbial Diseases, Yale School of Public Health, New Haven, CT, United States of America
| | - Danielle Bloch
- Department of Health and Mental Hygiene, New York City, NY, United States of America
| | - Aurélien Vigneron
- Department of Epidemiology of Microbial Diseases, Yale School of Public Health, New Haven, CT, United States of America
| | - T. J. Johnson
- Department of Ecology and Evolutionary Biology, Yale University, New Haven, CT, United States of America
| | - Kirstin Dion
- Department of Ecology and Evolutionary Biology, Yale University, New Haven, CT, United States of America
| | - Brian L. Weiss
- Department of Epidemiology of Microbial Diseases, Yale School of Public Health, New Haven, CT, United States of America
| | - Elizabeth Opiyo
- Department of Biology, University of Mississippi, University, MS, United States of America
| | - Adalgisa Caccone
- Department of Ecology and Evolutionary Biology, Yale University, New Haven, CT, United States of America
| | - Serap Aksoy
- Department of Epidemiology of Microbial Diseases, Yale School of Public Health, New Haven, CT, United States of America
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De Meeûs T, Ravel S, Solano P, Bouyer J. Negative Density-dependent Dispersal in Tsetse Flies: A Risk for Control Campaigns? Trends Parasitol 2019; 35:615-621. [PMID: 31201131 DOI: 10.1016/j.pt.2019.05.007] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2019] [Revised: 05/21/2019] [Accepted: 05/21/2019] [Indexed: 12/13/2022]
Abstract
Tsetse flies are vectors of parasites that cause diseases responsible for significant economic losses and health issues in sub-Saharan Africa, including sleeping sickness in humans and nagana in domestic animals. Efficient vector-control campaigns require good knowledge of the demographic parameters of the targeted populations. In the last decade, population genetics emerged as a convenient way to measure population densities and dispersal in tsetse flies. Here, by revealing a strong negative density-dependent dispersal in two dimensions, we suggest that control campaigns might unleash dispersal from untreated areas. If confirmed by direct measurement of dispersal before and after control campaigns, area-wide and/or sequential treatments of neighboring sites will be necessary to prevent this issue.
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Affiliation(s)
| | - Sophie Ravel
- Intertryp, IRD, Cirad, Univ Montpellier, Montpellier, France
| | - Philippe Solano
- Intertryp, IRD, Cirad, Univ Montpellier, Montpellier, France
| | - Jérémy Bouyer
- Intertryp, IRD, Cirad, Univ Montpellier, Montpellier, France; Astre, Cirad, Inra, Montpellier, France; Insect Pest Control Laboratory, Joint Food and Agriculture Organization of the United Nations/International Atomic Energy Agency Program of Nuclear Techniques in Food and Agriculture, A-1400, Vienna, Austria
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20
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Manangwa O, De Meeûs T, Grébaut P, Ségard A, Byamungu M, Ravel S. Detecting Wahlund effects together with amplification problems: Cryptic species, null alleles and short allele dominance in Glossina pallidipes populations from Tanzania. Mol Ecol Resour 2019; 19:757-772. [PMID: 30615304 DOI: 10.1111/1755-0998.12989] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2018] [Revised: 09/27/2018] [Accepted: 12/19/2018] [Indexed: 12/20/2022]
Abstract
Population genetics is a convenient tool to study the population biology of non-model and hard to sample species. This is particularly true for parasites and vectors. Heterozygote deficits and/or linkage disequilibrium often occur in such studies and detecting the origin of those (Wahlund effect, reproductive system or amplification problems) is uneasy. We used new tools (correlation between the number of times a locus is found in significant linkage disequilibrium and its genetic diversity, correlations between Wright's FIS and FST , FIS and number of missing data, FIT and allele size and standard errors comparisons) for the first time on a real data set of tsetse flies, a vector of dangerous diseases to humans and domestic animals in sub-Saharan Africa. With these new tools, and cleaning data from null allele, temporal heterogeneity and short allele dominance effects, we unveiled the coexistence of two highly divergent cryptic clades in the same sites. These results are in line with other studies suggesting that the biodiversity of many taxa still largely remain undescribed, in particular pathogenic agents and their vectors. Our results also advocate that including individuals from different cohorts tends to bias subdivision measures and that keeping loci with short allele dominance and/or too frequent missing data seriously jeopardize parameter's estimations. Finally, separated analyses of the two clades suggest very small tsetse densities and relatively large dispersal.
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Affiliation(s)
- Oliver Manangwa
- Vector and Vector Borne Disease Research Institute, Tanga, Tanzania
| | | | - Pascal Grébaut
- Intertryp, IRD, CIRAD, Univ Montpellier, Montpellier, France
| | - Adeline Ségard
- Intertryp, IRD, CIRAD, Univ Montpellier, Montpellier, France
| | | | - Sophie Ravel
- Intertryp, IRD, CIRAD, Univ Montpellier, Montpellier, France
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21
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Kariithi HM, Meki IK, Schneider DI, De Vooght L, Khamis FM, Geiger A, Demirbaş-Uzel G, Vlak JM, iNCE IA, Kelm S, Njiokou F, Wamwiri FN, Malele II, Weiss BL, Abd-Alla AMM. Enhancing vector refractoriness to trypanosome infection: achievements, challenges and perspectives. BMC Microbiol 2018; 18:179. [PMID: 30470182 PMCID: PMC6251094 DOI: 10.1186/s12866-018-1280-y] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
With the absence of effective prophylactic vaccines and drugs against African trypanosomosis, control of this group of zoonotic neglected tropical diseases depends the control of the tsetse fly vector. When applied in an area-wide insect pest management approach, the sterile insect technique (SIT) is effective in eliminating single tsetse species from isolated populations. The need to enhance the effectiveness of SIT led to the concept of investigating tsetse-trypanosome interactions by a consortium of researchers in a five-year (2013-2018) Coordinated Research Project (CRP) organized by the Joint Division of FAO/IAEA. The goal of this CRP was to elucidate tsetse-symbiome-pathogen molecular interactions to improve SIT and SIT-compatible interventions for trypanosomoses control by enhancing vector refractoriness. This would allow extension of SIT into areas with potential disease transmission. This paper highlights the CRP's major achievements and discusses the science-based perspectives for successful mitigation or eradication of African trypanosomosis.
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Affiliation(s)
- Henry M Kariithi
- Biotechnology Research Institute, Kenya Agricultural & Livestock Research Organization, P.O Box 57811, 00200, Kaptagat Rd, Loresho, Nairobi, Kenya
| | - Irene K Meki
- Insect Pest Control Laboratory, FAO/IAEA Agriculture & Biotechnology Laboratory, IAEA Laboratories Seibersdorf, A-2444 Seibersdorf, Austria
- Laboratory of Virology, Wageningen University and Research, Wageningen, 6708 PB The Netherlands
| | - Daniela I Schneider
- Department of Epidemiology of Microbial Diseases, Yale School of Public Health, 60 College Street, New Haven, CT 06510 USA
| | - Linda De Vooght
- Department of Biomedical Sciences, Institute of Tropical Medicine, Antwerp, Belgium
| | - Fathiya M Khamis
- International Centre of Insect Physiology and Ecology, P.O. Box 30772, 00100, Nairobi, Kenya
| | - Anne Geiger
- INTERTRYP, Institut de Recherche pour le Développement, University of Montpellier, Montpellier, France
| | - Guler Demirbaş-Uzel
- Insect Pest Control Laboratory, FAO/IAEA Agriculture & Biotechnology Laboratory, IAEA Laboratories Seibersdorf, A-2444 Seibersdorf, Austria
| | - Just M Vlak
- Laboratory of Virology, Wageningen University and Research, Wageningen, 6708 PB The Netherlands
| | - ikbal Agah iNCE
- Institute of Chemical, Environmental & Biological Engineering, Research Area Biochemical Technology, Vienna University of Technology, Gumpendorfer Straße 1a, 1060 Vienna, Austria
| | - Sorge Kelm
- Department of Medical Microbiology, Acıbadem Mehmet Ali Aydınlar University, School of Medicine, 34752, Ataşehir, Istanbul, Turkey
| | - Flobert Njiokou
- Centre for Biomolecular Interactions Bremen, Faculty for Biology & Chemistry, Universität Bremen, Bibliothekstraße 1, 28359 Bremen, Germany
| | - Florence N Wamwiri
- Laboratory of Parasitology and Ecology, Faculty of Sciences, Department of Animal Biology and Physiology, University of Yaoundé 1, Yaoundé, BP 812 Cameroon
| | - Imna I Malele
- Trypanosomiasis Research Centre, Kenya Agricultural & Livestock Research Organization, P.O. Box 362-00902, Kikuyu, Kenya
| | - Brian L Weiss
- Department of Epidemiology of Microbial Diseases, Yale School of Public Health, 60 College Street, New Haven, CT 06510 USA
| | - Adly M M Abd-Alla
- Molecular Department, Vector and Vector Borne Diseases Institute, Tanzania Veterinary Laboratory Agency, Majani Mapana, Off Korogwe Road, Box, 1026 Tanga, Tanzania
- Insect Pest Control Laboratory, FAO/IAEA Agriculture & Biotechnology Laboratory, IAEA Laboratories Seibersdorf, A-2444 Seibersdorf, Austria
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22
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Krafsur ES, Maudlin I. Tsetse fly evolution, genetics and the trypanosomiases - A review. INFECTION GENETICS AND EVOLUTION 2018; 64:185-206. [PMID: 29885477 DOI: 10.1016/j.meegid.2018.05.033] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/24/2018] [Revised: 05/30/2018] [Accepted: 05/31/2018] [Indexed: 01/27/2023]
Abstract
This reviews work published since 2007. Relative efforts devoted to the agents of African trypanosomiasis and their tsetse fly vectors are given by the numbers of PubMed accessions. In the last 10 years PubMed citations number 3457 for Trypanosoma brucei and 769 for Glossina. The development of simple sequence repeats and single nucleotide polymorphisms afford much higher resolution of Glossina and Trypanosoma population structures than heretofore. Even greater resolution is offered by partial and whole genome sequencing. Reproduction in T. brucei sensu lato is principally clonal although genetic recombination in tsetse salivary glands has been demonstrated in T. b. brucei and T. b. rhodesiense but not in T. b. gambiense. In the past decade most genetic attention was given to the chief human African trypanosomiasis vectors in subgenus Nemorhina e.g., Glossina f. fuscipes, G. p. palpalis, and G. p. gambiense. The chief interest in Nemorhina population genetics seemed to be finding vector populations sufficiently isolated to enable efficient and long-lasting suppression. To this end estimates were made of gene flow, derived from FST and its analogues, and Ne, the size of a hypothetical population equivalent to that under study. Genetic drift was greater, gene flow and Ne typically lesser in savannah inhabiting tsetse (subgenus Glossina) than in riverine forms (Nemorhina). Population stabilities were examined by sequential sampling and genotypic analysis of nuclear and mitochondrial genomes in both groups and found to be stable. Gene frequencies estimated in sequential samplings differed by drift and allowed estimates of effective population numbers that were greater for Nemorhina spp than Glossina spp. Prospects are examined of genetic methods of vector control. The tsetse long generation time (c. 50 d) is a major contraindication to any suggested genetic method of tsetse population manipulation. Ecological and modelling research convincingly show that conventional methods of targeted insecticide applications and traps/targets can achieve cost-effective reduction in tsetse densities.
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Affiliation(s)
- E S Krafsur
- Department of Entomology, Iowa State University, Ames, IA 50011, USA.
| | - Ian Maudlin
- School of Biomedical Sciences, The University of Edinburgh, Scotland, UK
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Saarman N, Burak M, Opiro R, Hyseni C, Echodu R, Dion K, Opiyo EA, Dunn AW, Amatulli G, Aksoy S, Caccone A. A spatial genetics approach to inform vector control of tsetse flies ( Glossina fuscipes fuscipes) in Northern Uganda. Ecol Evol 2018; 8:5336-5354. [PMID: 29938057 PMCID: PMC6010828 DOI: 10.1002/ece3.4050] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2018] [Revised: 02/22/2018] [Accepted: 02/23/2018] [Indexed: 11/09/2022] Open
Abstract
Tsetse flies (genus Glossina) are the only vector for the parasitic trypanosomes responsible for sleeping sickness and nagana across sub-Saharan Africa. In Uganda, the tsetse fly Glossina fuscipes fuscipes is responsible for transmission of the parasite in 90% of sleeping sickness cases, and co-occurrence of both forms of human-infective trypanosomes makes vector control a priority. We use population genetic data from 38 samples from northern Uganda in a novel methodological pipeline that integrates genetic data, remotely sensed environmental data, and hundreds of field-survey observations. This methodological pipeline identifies isolated habitat by first identifying environmental parameters correlated with genetic differentiation, second, predicting spatial connectivity using field-survey observations and the most predictive environmental parameter(s), and third, overlaying the connectivity surface onto a habitat suitability map. Results from this pipeline indicated that net photosynthesis was the strongest predictor of genetic differentiation in G. f. fuscipes in northern Uganda. The resulting connectivity surface identified a large area of well-connected habitat in northwestern Uganda, and twenty-four isolated patches on the northeastern margin of the G. f. fuscipes distribution. We tested this novel methodological pipeline by completing an ad hoc sample and genetic screen of G. f. fuscipes samples from a model-predicted isolated patch, and evaluated whether the ad hoc sample was in fact as genetically isolated as predicted. Results indicated that genetic isolation of the ad hoc sample was as genetically isolated as predicted, with differentiation well above estimates made in samples from within well-connected habitat separated by similar geographic distances. This work has important practical implications for the control of tsetse and other disease vectors, because it provides a way to identify isolated populations where it will be safer and easier to implement vector control and that should be prioritized as study sites during the development and improvement of vector control methods.
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Affiliation(s)
- Norah Saarman
- Department of Ecology and Evolutionary BiologyYale UniversityNew HavenConnecticut
| | - Mary Burak
- Department of Ecology and Evolutionary BiologyYale UniversityNew HavenConnecticut
| | - Robert Opiro
- Department of BiologyFaculty of ScienceGulu UniversityGuluLaroo DivisionUganda
| | - Chaz Hyseni
- Department of BiologyUniversity of MississippiOxfordMassachusetts
| | - Richard Echodu
- Department of BiologyFaculty of ScienceGulu UniversityGuluLaroo DivisionUganda
| | - Kirstin Dion
- Department of Ecology and Evolutionary BiologyYale UniversityNew HavenConnecticut
| | - Elizabeth A. Opiyo
- Department of BiologyFaculty of ScienceGulu UniversityGuluLaroo DivisionUganda
| | - Augustine W. Dunn
- Division of Genetics and GenomicsBoston Children's HospitalBostonMassachusetts
| | - Giuseppe Amatulli
- Department of GeoComputation and Spatial ScienceYale School of Forestry and Environmental StudiesNew HavenConnecticut
| | - Serap Aksoy
- Department of Epidemiology of Microbial DiseasesYale School of Public HealthNew HavenConnecticut
| | - Adalgisa Caccone
- Department of Ecology and Evolutionary BiologyYale UniversityNew HavenConnecticut
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24
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Uncovering Genomic Regions Associated with Trypanosoma Infections in Wild Populations of the Tsetse Fly Glossina fuscipes. G3-GENES GENOMES GENETICS 2018; 8:887-897. [PMID: 29343494 PMCID: PMC5844309 DOI: 10.1534/g3.117.300493] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Vector-borne diseases are responsible for > 1 million deaths every year but genomic resources for most species responsible for their transmission are limited. This is true for neglected diseases such as sleeping sickness (Human African Trypanosomiasis), a disease caused by Trypanosoma parasites vectored by several species of tseste flies within the genus Glossina. We describe an integrative approach that identifies statistical associations between trypanosome infection status of Glossina fuscipes fuscipes (Gff) flies from Uganda, for which functional studies are complicated because the species cannot be easily maintained in laboratory colonies, and ∼73,000 polymorphic sites distributed across the genome. Then, we identify candidate genes involved in Gff trypanosome susceptibility by taking advantage of genomic resources from a closely related species, G. morsitans morsitans (Gmm). We compiled a comprehensive transcript library from 72 published and unpublished RNAseq experiments of trypanosome-infected and uninfected Gmm flies, and improved the current Gmm transcriptome assembly. This new assembly was then used to enhance the functional annotations on the Gff genome. As a consequence, we identified 56 candidate genes in the vicinity of the 18 regions associated with Trypanosoma infection status in Gff. Twenty-nine of these genes were differentially expressed (DE) among parasite-infected and uninfected Gmm, suggesting that their orthologs in Gff may correlate with disease transmission. These genes were involved in DNA regulation, neurophysiological functions, and immune responses. We highlight the power of integrating population and functional genomics from related species to enhance our understanding of the genetic basis of physiological traits, particularly in nonmodel organisms.
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25
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Benelli G. Gold nanoparticles - against parasites and insect vectors. Acta Trop 2018; 178:73-80. [PMID: 29092797 DOI: 10.1016/j.actatropica.2017.10.021] [Citation(s) in RCA: 85] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2017] [Revised: 10/16/2017] [Accepted: 10/26/2017] [Indexed: 01/13/2023]
Abstract
Nanomaterials are currently considered for many biological, biomedical and environmental purposes, due to their outstanding physical and chemical properties. The synthesis of gold nanoparticles (Au NPs) is of high interest for research in parasitology and entomology, since these nanomaterials showed promising applications, ranging from detection techniques to drug development, against a rather wide range of parasites of public health relevance, as well as on insect vectors. Here, I reviewed current knowledge about the bioactivity of Au NPs on selected insect species of public health relevance, including major mosquito vectors, such as Aedes aegypti, Anopheles stephensi and Culex quinquefasciatus. The toxicity of Au NPs against helminths was reviewed, covering Schistosoma mansoni trematodes as well as Raillietina cestodes. Furthermore, I summarized the information available on the antiparasitic role of Au NPs in the fight against malaria, leishmaniosis, toxoplasmosis, trypanosomiasis, cryptosporidiosis, and microsporidian parasites affecting human and animals health. Besides, I examined the employ of Au NPs as biomarkers, tools for diagnostics and adjuvants for the induction of transmission blocking immunity in malaria vaccine research. In the final section, major challenges and future outlooks for further research are discussed, with special reference to the pressing need of further knowledge about the effect of Au NPs on other arthropod vectors, such as ticks, tsetse flies, tabanids, sandflies and blackflies, and related ecotoxicology assays.
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26
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Light JE, Harper SE, Johnson KP, Demastes JW, Spradling TA. Development and Characterization of 12 Novel Polymorphic Microsatellite Loci for the Mammal Chewing Louse Geomydoecus aurei (Insecta: Phthiraptera) and a Comparison of Next-Generation Sequencing Approaches for Use in Parasitology. J Parasitol 2017; 104:89-95. [PMID: 28985160 DOI: 10.1645/17-130] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
Next-generation sequencing methodologies open the door for evolutionary studies of wildlife parasites. We used 2 next-generation sequencing approaches to discover microsatellite loci in the pocket gopher chewing louse Geomydoecus aurei for use in population genetic studies. In one approach, we sequenced a library enriched for microsatellite loci; in the other approach, we mined microsatellites from genomic sequences. Following microsatellite discovery, promising loci were tested for amplification and polymorphism in 390 louse individuals from 13 pocket gopher hosts. In total, 12 loci were selected for analysis (6 from each methodology), none of which exhibited evidence of null alleles or heterozygote deficiencies. These 12 loci showed adequate genetic diversity for population-level analyses, with 3-9 alleles per locus with an average HE per locus ranging from 0.32 to 0.70. Analysis of Molecular Variance (AMOVA) indicated that genetic variation among infrapopulations accounts for a low, but significant, percentage of the overall genetic variation, and individual louse infrapopulations showed FST values that were significantly different from zero in the majority of pairwise infrapopulation comparisons, despite all 13 infrapopulations being taken from the same locality. Therefore, these 12 polymorphic markers will be useful at the infrapopulation and population levels for future studies involving G. aurei. This study shows that next-generation sequencing methodologies can successfully be used to efficiently obtain data for a variety of evolutionary questions.
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Affiliation(s)
- J E Light
- Department of Wildlife and Fisheries Sciences, Texas A&M University, 534 John Kimbrough Blvd., College Station, Texas 77843
| | - S E Harper
- Department of Wildlife and Fisheries Sciences, Texas A&M University, 534 John Kimbrough Blvd., College Station, Texas 77843
| | - K P Johnson
- Department of Wildlife and Fisheries Sciences, Texas A&M University, 534 John Kimbrough Blvd., College Station, Texas 77843
| | - J W Demastes
- Department of Wildlife and Fisheries Sciences, Texas A&M University, 534 John Kimbrough Blvd., College Station, Texas 77843
| | - T A Spradling
- Department of Wildlife and Fisheries Sciences, Texas A&M University, 534 John Kimbrough Blvd., College Station, Texas 77843
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