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Marcantonio M, Winokur OC, Barker CM. Revisiting Alkali Metals As a Tool to Characterize Patterns of Mosquito Dispersal and Oviposition. INSECTS 2019; 10:insects10080220. [PMID: 31344901 PMCID: PMC6723755 DOI: 10.3390/insects10080220] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/22/2019] [Revised: 07/08/2019] [Accepted: 07/12/2019] [Indexed: 11/16/2022]
Abstract
Mark-recapture methods constitute a set of classical ecological tools that are used to collect information on species dispersal and population size. These methods have advanced knowledge in disparate scientific fields, from conservation biology to pest control. Gathering information on the dispersal of mosquito species, such as Aedes aegypti, has become critical since the recognition of their role as vectors of pathogens. Here, we evaluate a method to mark mosquitoes that exploits the rare alkali metals rubidium (Rb) and caesium (Cs), which have been used previously to mark adult insects through feeding. We revised this method by adding Rb and Cs directly to water in which the immature stages of Ae. aegypti were allowed to develop. We then assessed the effect of Rb- and Cs-enriched water on fitness, survival and bioaccumulation in both adult females and their eggs. Results indicated that Cs had adverse effects on Ae. aegypti, even at low concentrations, whereas Rb at low concentrations had no measured effects on exposed individuals and accumulated at detectable levels in adult females. The method described here relies on passive uptake of Rb during immature stages, which has the benefit of avoiding handling or manipulation of the dispersive adults, which enables purer measurement of movement. Moreover, we demonstrated that Rb was transferred efficiently from the marked females to their eggs. To our knowledge, Rb is the only marker used for mosquitoes that has been shown to transfer vertically from females to eggs. The application of Rb rather than more traditional markers may therefore increase the quality (no impact on released individuals) and quantity (both adults and eggs are marked) of data collected during MR studies. The method we propose here can be used in combination with other markers, such as stable isotopes, in order to maximize the information collected during MR experiments.
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Affiliation(s)
- Matteo Marcantonio
- Department of Pathology, Microbiology, and Immunology, School of Veterinary Medicine, University of California, Davis, CA 95616, USA.
| | - Olivia C Winokur
- Department of Pathology, Microbiology, and Immunology, School of Veterinary Medicine, University of California, Davis, CA 95616, USA
| | - Christopher M Barker
- Department of Pathology, Microbiology, and Immunology, School of Veterinary Medicine, University of California, Davis, CA 95616, USA.
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52
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Schebeck M, Feldkirchner L, Stauffer C, Schuler H. Dynamics of an Ongoing Wolbachia Spread in the European Cherry Fruit Fly, Rhagoletis cerasi (Diptera: Tephritidae). INSECTS 2019; 10:insects10060172. [PMID: 31208002 PMCID: PMC6627601 DOI: 10.3390/insects10060172] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/16/2019] [Revised: 06/06/2019] [Accepted: 06/11/2019] [Indexed: 11/20/2022]
Abstract
Numerous terrestrial arthropods are infected with the alphaproteobacterium Wolbachia. This endosymbiont is usually transmitted vertically from infected females to their offspring and can alter the reproduction of hosts through various manipulations, like cytoplasmic incompatibility (CI), enhancing its spread in new host populations. Studies on the spatial and temporal dynamics of Wolbachia under natural conditions are scarce. Here, we analyzed Wolbachia infection frequencies in populations of the European cherry fruit fly, Rhagoletis cerasi (L.), in central Germany—an area of an ongoing spread of the CI-inducing strain wCer2. In total, 295 individuals from 19 populations were PCR-screened for the presence of wCer2 and their mitochondrial haplotype. Results were compared with historic data to understand the infection dynamics of the ongoing wCer2 invasion. An overall wCer2 infection frequency of about 30% was found, ranging from 0% to 100% per population. In contrast to an expected smooth transition from wCer2-infected to completely wCer2-uninfected populations, a relatively scattered infection pattern across geography was observed. Moreover, a strong Wolbachia-haplotype association was detected, with only a few rare misassociations. Our results show a complex dynamic of an ongoing Wolbachia spread in natural field populations of R. cerasi.
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Affiliation(s)
- Martin Schebeck
- Department of Forest and Soil Sciences, University of Natural Resources and Life Sciences Vienna, BOKU, Peter-Jordan-Straße 82/I, A-1190 Vienna, Austria.
| | - Lukas Feldkirchner
- Department of Forest and Soil Sciences, University of Natural Resources and Life Sciences Vienna, BOKU, Peter-Jordan-Straße 82/I, A-1190 Vienna, Austria.
| | - Christian Stauffer
- Department of Forest and Soil Sciences, University of Natural Resources and Life Sciences Vienna, BOKU, Peter-Jordan-Straße 82/I, A-1190 Vienna, Austria.
| | - Hannes Schuler
- Faculty of Science and Technology, Free University of Bozen-Bolzano, Universitätsplatz 5, I-39100 Bozen-Bolzano, Italy.
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53
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Jasper M, Schmidt TL, Ahmad NW, Sinkins SP, Hoffmann AA. A genomic approach to inferring kinship reveals limited intergenerational dispersal in the yellow fever mosquito. Mol Ecol Resour 2019; 19:1254-1264. [PMID: 31125998 PMCID: PMC6790672 DOI: 10.1111/1755-0998.13043] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2019] [Revised: 05/13/2019] [Accepted: 05/17/2019] [Indexed: 12/21/2022]
Abstract
Understanding past dispersal and breeding events can provide insight into ecology and evolution and can help inform strategies for conservation and the control of pest species. However, parent-offspring dispersal can be difficult to investigate in rare species and in small pest species such as mosquitoes. Here, we develop a methodology for estimating parent-offspring dispersal from the spatial distribution of close kin, using pairwise kinship estimates derived from genome-wide single nucleotide polymorphisms (SNPs). SNPs were scored in 162 Aedes aegypti (yellow fever mosquito) collected from eight close-set, high-rise apartment buildings in an area of Malaysia with high dengue incidence. We used the SNPs to reconstruct kinship groups across three orders of kinship. We transformed the geographical distances between all kin pairs within each kinship category into axial standard deviations of these distances, then decomposed these into components representing past dispersal events. From these components, we isolated the axial standard deviation of parent-offspring dispersal and estimated neighbourhood area (129 m), median parent-offspring dispersal distance (75 m) and oviposition dispersal radius within a gonotrophic cycle (36 m). We also analysed genetic structure using distance-based redundancy analysis and linear regression, finding isolation by distance both within and between buildings and estimating neighbourhood size at 268 individuals. These findings indicate the scale required to suppress local outbreaks of arboviral disease and to target releases of modified mosquitoes for mosquito and disease control. Our methodology is readily implementable for studies of other species, including pests and species of conservation significance.
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Affiliation(s)
- Moshe Jasper
- School of BioSciences, Bio21 Institute, University of Melbourne, Parkville, Victoria, Australia
| | - Thomas L Schmidt
- School of BioSciences, Bio21 Institute, University of Melbourne, Parkville, Victoria, Australia
| | - Nazni W Ahmad
- Institute for Medical Research, Ministry of Health Malaysia, Kuala Lumpur, Malaysia
| | | | - Ary A Hoffmann
- School of BioSciences, Bio21 Institute, University of Melbourne, Parkville, Victoria, Australia
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54
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Schmidt TL, van Rooyen AR, Chung J, Endersby‐Harshman NM, Griffin PC, Sly A, Hoffmann AA, Weeks AR. Tracking genetic invasions: Genome-wide single nucleotide polymorphisms reveal the source of pyrethroid-resistant Aedes aegypti (yellow fever mosquito) incursions at international ports. Evol Appl 2019; 12:1136-1146. [PMID: 31297145 PMCID: PMC6597869 DOI: 10.1111/eva.12787] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2019] [Revised: 02/25/2019] [Accepted: 02/28/2019] [Indexed: 01/06/2023] Open
Abstract
Biological invasions are increasing globally in number and extent despite efforts to restrict their spread. Knowledge of incursion pathways is necessary to prevent new invasions and to design effective biosecurity protocols at source and recipient locations. This study uses genome-wide single nucleotide polymorphisms (SNPs) to determine the origin of 115 incursive Aedes aegypti(yellow fever mosquito) detected at international ports in Australia and New Zealand. We also genotyped mosquitoes at three point mutations in the voltage-sensitive sodium channel (Vssc) gene: V1016G, F1534C and S989P. These mutations confer knockdown resistance to synthetic pyrethroid insecticides, widely used for controlling invertebrate pests. We first delineated reference populations using Ae. aegypti sampled from 15 locations in Asia, South America, Australia and the Pacific Islands. Incursives were assigned to these populations using discriminant analysis of principal components (DAPC) and an assignment test with a support vector machine predictive model. Bali, Indonesia, was the most common origin of Ae. aegypti detected in Australia, while Ae. aegypti detected in New Zealand originated from Pacific Islands such as Fiji. Most incursives had the same allelic genotype across the three Vsscgene point mutations, which confers strong resistance to synthetic pyrethroids, the only insecticide class used in current, widely implemented aircraft disinsection protocols endorsed by the World Health Organization (WHO). Additionally, all internationally assigned Ae. aegypti had Vssc point mutations linked to pyrethroid resistance that are not found in Australian populations. These findings demonstrate that protocols for preventing introductions of invertebrates must consider insecticide resistance, and highlight the usefulness of genomic data sets for managing global biosecurity objectives.
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Affiliation(s)
- Thomas L. Schmidt
- Bio21 Institute, School of BioSciencesThe University of MelbourneParkvilleVictoriaAustralia
| | | | - Jessica Chung
- Bio21 Institute, School of BioSciencesThe University of MelbourneParkvilleVictoriaAustralia
- Melbourne BioinformaticsThe University of MelbourneParkvilleVictoriaAustralia
| | | | - Philippa C. Griffin
- Bio21 Institute, School of BioSciencesThe University of MelbourneParkvilleVictoriaAustralia
| | - Angus Sly
- Department of Agriculture and Water ResourcesBrisbane AirportQueenslandAustralia
| | - Ary A. Hoffmann
- Bio21 Institute, School of BioSciencesThe University of MelbourneParkvilleVictoriaAustralia
| | - Andrew R. Weeks
- Bio21 Institute, School of BioSciencesThe University of MelbourneParkvilleVictoriaAustralia
- cesar Pty LtdParkvilleVictoriaAustralia
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55
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Bennett KL, Gómez Martínez C, Almanza A, Rovira JR, McMillan WO, Enriquez V, Barraza E, Diaz M, Sanchez-Galan JE, Whiteman A, Gittens RA, Loaiza JR. High infestation of invasive Aedes mosquitoes in used tires along the local transport network of Panama. Parasit Vectors 2019; 12:264. [PMID: 31133041 PMCID: PMC6537307 DOI: 10.1186/s13071-019-3522-8] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2019] [Accepted: 05/20/2019] [Indexed: 01/03/2023] Open
Abstract
BACKGROUND The long-distance dispersal of the invasive disease vectors Aedes aegypti and Aedes albopictus has introduced arthropod-borne viruses into new geographical regions, causing a significant medical and economic burden. The used-tire industry is an effective means of Aedes dispersal, yet studies to determine Aedes occurrence and the factors influencing their distribution along local transport networks are lacking. To assess infestation along the primary transport network of Panama we documented all existing garages that trade used tires on the highway and surveyed a subset for Ae. aegypti and Ae. albopictus. We also assess the ability of a mass spectrometry approach to classify mosquito eggs by comparing our findings to those based on traditional larval surveillance. RESULTS Both Aedes species had a high infestation rate in garages trading used tires along the highways, providing a conduit for rapid dispersal across Panama. However, generalized linear models revealed that the presence of Ae. aegypti is associated with an increase in road density by a log-odds of 0.44 (0.73 ± 0.16; P = 0.002), while the presence of Ae. albopictus is associated with a decrease in road density by a log-odds of 0.36 (0.09 ± 0.63; P = 0.008). Identification of mosquito eggs by mass spectrometry depicted similar occurrence patterns for both Aedes species as that obtained with traditional rearing methods. CONCLUSIONS Garages trading used tires along highways should be targeted for the surveillance and control of Aedes-mosquitoes and the diseases they transmit. The identification of mosquito eggs using mass spectrometry allows for the rapid evaluation of Aedes presence, affording time and cost advantages over traditional vector surveillance; this is of importance for disease risk assessment.
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Affiliation(s)
- Kelly L Bennett
- Smithsonian Tropical Research Institute, Balboa Ancón, Republic of Panama
| | | | - Alejandro Almanza
- Smithsonian Tropical Research Institute, Balboa Ancón, Republic of Panama
- Instituto de Investigaciones Científicas y Servicios de Alta Tecnología (INDICASAT AIP), Panamá, Republic of Panama
| | - Jose R Rovira
- Smithsonian Tropical Research Institute, Balboa Ancón, Republic of Panama
- Instituto de Investigaciones Científicas y Servicios de Alta Tecnología (INDICASAT AIP), Panamá, Republic of Panama
| | - W Owen McMillan
- Smithsonian Tropical Research Institute, Balboa Ancón, Republic of Panama
| | | | | | | | | | - Ari Whiteman
- Smithsonian Tropical Research Institute, Balboa Ancón, Republic of Panama
- University of North Carolina, Charlotte, NC, USA
| | - Rolando A Gittens
- Instituto de Investigaciones Científicas y Servicios de Alta Tecnología (INDICASAT AIP), Panamá, Republic of Panama.
| | - Jose R Loaiza
- Smithsonian Tropical Research Institute, Balboa Ancón, Republic of Panama.
- Instituto de Investigaciones Científicas y Servicios de Alta Tecnología (INDICASAT AIP), Panamá, Republic of Panama.
- Universidad de Panamá, Panamá, Republic of Panama.
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56
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Ross PA, Ritchie SA, Axford JK, Hoffmann AA. Loss of cytoplasmic incompatibility in Wolbachia-infected Aedes aegypti under field conditions. PLoS Negl Trop Dis 2019; 13:e0007357. [PMID: 31002720 PMCID: PMC6493766 DOI: 10.1371/journal.pntd.0007357] [Citation(s) in RCA: 75] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2018] [Revised: 05/01/2019] [Accepted: 04/02/2019] [Indexed: 01/21/2023] Open
Abstract
Wolbachia bacteria are now being introduced into Aedes aegypti mosquito populations for dengue control. When Wolbachia infections are at a high frequency, they influence the local transmission of dengue by direct virus blocking as well as deleterious effects on vector mosquito populations. However, the effectiveness of this strategy could be influenced by environmental temperatures that decrease Wolbachia density, thereby reducing the ability of Wolbachia to invade and persist in the population and block viruses. We reared wMel-infected Ae. aegypti larvae in the field during the wet season in Cairns, North Queensland. Containers placed in the shade produced mosquitoes with a high Wolbachia density and little impact on cytoplasmic incompatibility. However, in 50% shade where temperatures reached 39°C during the day, wMel-infected males partially lost their ability to induce cytoplasmic incompatibility and females had greatly reduced egg hatch when crossed to infected males. In a second experiment under somewhat hotter conditions (>40°C in 50% shade), field-reared wMel-infected females had their egg hatch reduced to 25% when crossed to field-reared wMel-infected males. Wolbachia density was reduced in 50% shade for both sexes in both experiments, with some mosquitoes cleared of their Wolbachia infections entirely. To investigate the critical temperature range for the loss of Wolbachia infections, we held Ae. aegypti eggs in thermocyclers for one week at a range of cyclical temperatures. Adult wMel density declined when eggs were held at 26–36°C or above with complete loss at 30–40°C, while the density of wAlbB remained high until temperatures were lethal. These findings suggest that high temperature effects on Wolbachia are potentially substantial when breeding containers are exposed to partial sunlight but not shade. Heat stress could reduce the ability of Wolbachia infections to invade mosquito populations in some locations and may compromise the ability of Wolbachia to block virus transmission in the field. Temperature effects may also have an ecological impact on mosquito populations given that a proportion of the population becomes self-incompatible. Aedes aegypti mosquitoes infected with Wolbachia symbionts are being deployed in the tropics as a way of reducing disease transmission. Some Wolbachia strains are vulnerable to high temperatures but these effects have not been evaluated outside of a laboratory setting. We reared Ae. aegypti infected with the wMel strain of Wolbachia in the field during the wet season in Cairns, Australia, where the first releases of Wolbachia-infected Ae. aegypti took place. wMel-infected mosquitoes became partially self-incompatible, with reduced egg hatch, when larvae were reared in partial shade where maximum daily temperatures exceeded 39°C. Under these conditions the amount of Wolbachia in adult mosquitoes was reduced to less than 1% of laboratory-reared mosquitoes on average, while some mosquitoes were cleared of Wolbachia entirely. In contrast, wMel was stable when mosquitoes were reared under cooler conditions in full shade. Field trials with the wMel strain are now underway in over 10 countries, but high temperatures in some locales may constrain the ability of Wolbachia to invade natural mosquito populations and block disease transmission.
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Affiliation(s)
- Perran A. Ross
- Pest and Environmental Adaptation Research Group, Bio21 Institute and the School of BioSciences, The University of Melbourne, Parkville, Victoria, Australia
- * E-mail:
| | - Scott A. Ritchie
- College of Public Health, Medical and Veterinary Sciences, James Cook University, Smithfield, Queensland, Australia
- Australian Institute of Tropical Health and Medicine, James Cook University, Smithfield, Queensland, Australia
| | - Jason K. Axford
- Pest and Environmental Adaptation Research Group, Bio21 Institute and the School of BioSciences, The University of Melbourne, Parkville, Victoria, Australia
| | - Ary A. Hoffmann
- Pest and Environmental Adaptation Research Group, Bio21 Institute and the School of BioSciences, The University of Melbourne, Parkville, Victoria, Australia
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57
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Ross PA, Endersby‐Harshman NM, Hoffmann AA. A comprehensive assessment of inbreeding and laboratory adaptation in Aedes aegypti mosquitoes. Evol Appl 2019; 12:572-586. [PMID: 30828375 PMCID: PMC6383739 DOI: 10.1111/eva.12740] [Citation(s) in RCA: 49] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2018] [Revised: 09/04/2018] [Accepted: 11/11/2018] [Indexed: 12/13/2022] Open
Abstract
Modified Aedes aegypti mosquitoes reared in laboratories are being released around the world to control wild mosquito populations and the diseases they transmit. Several efforts have failed due to poor competitiveness of the released mosquitoes. We hypothesized that colonized mosquito populations could suffer from inbreeding depression and adapt to laboratory conditions, reducing their performance in the field. We established replicate populations of Ae. aegypti mosquitoes collected from Queensland, Australia, and maintained them in the laboratory for twelve generations at different census sizes. Mosquito colonies maintained at small census sizes (≤100 individuals) suffered from inbreeding depression due to low effective population sizes which were only 25% of the census size as estimated by SNP markers. Populations that underwent full-sib mating for nine consecutive generations had greatly reduced performance across all traits measured. We compared the established laboratory populations with their ancestral population resurrected from quiescent eggs for evidence of laboratory adaptation. The overall performance of laboratory populations maintained at a large census size (400 individuals) increased, potentially reflecting adaptation to artificial rearing conditions. However, most individual traits were unaffected, and patterns of adaptation were not consistent across populations. Differences between replicate populations may indicate that founder effects and drift affect experimental outcomes. Though we find limited evidence of laboratory adaptation, mosquitoes maintained at low population sizes can clearly suffer fitness costs, compromising the success of "rear-and-release" strategies for arbovirus control.
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Affiliation(s)
- Perran A. Ross
- Bio21 Institute and the School of BioSciencesThe University of MelbourneParkvilleVictoriaAustralia
| | | | - Ary A. Hoffmann
- Bio21 Institute and the School of BioSciencesThe University of MelbourneParkvilleVictoriaAustralia
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58
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Zheng B, Yu J. Characterization of Wolbachia enhancing domain in mosquitoes with imperfect maternal transmission. JOURNAL OF BIOLOGICAL DYNAMICS 2018; 12:596-610. [PMID: 30025503 DOI: 10.1080/17513758.2018.1499969] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/12/2017] [Accepted: 07/03/2018] [Indexed: 06/08/2023]
Abstract
A novel method to reduce the burden of dengue is to seed wild mosquitoes with Wolbachia-infected mosquitoes in dengue-endemic areas. Concerns in current mathematical models are to locate the Wolbachia introduction threshold. Our recent findings manifest that the threshold is highly dependent on the initial population size once Wolbachia infection alters the logistic control death rate of infected females. However, counting mosquitoes is beyond the realms of possibility. A plausible method is to monitor the infection frequency. We propose the concept of Wolbachia enhancing domain in which the infection frequency keeps increasing. A detailed description of the domain is presented. Our results suggest that both the initial population size and the infection frequency should be taken into account for optimal release strategies. Both Wolbachia fixation and extinction permit the oscillation of the infection frequency.
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Affiliation(s)
- Bo Zheng
- a College of Mathematics and Information Sciences , Guangzhou University , Guangzhou , People's Republic of China
- b Center for Applied Mathematics , Guangzhou University , Guangzhou , People's Republic of China
| | - Jianshe Yu
- a College of Mathematics and Information Sciences , Guangzhou University , Guangzhou , People's Republic of China
- b Center for Applied Mathematics , Guangzhou University , Guangzhou , People's Republic of China
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59
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Yeap HL, Endersby-Harshman NM, Hoffmann AA. The Effect of Nonrandom Mating on Wolbachia Dynamics: Implications for Population Replacement and Sterile Releases in Aedes Mosquitoes. Am J Trop Med Hyg 2018; 99:608-617. [PMID: 29968550 PMCID: PMC6169187 DOI: 10.4269/ajtmh.18-0178] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2018] [Accepted: 05/22/2018] [Indexed: 01/11/2023] Open
Abstract
Wolbachia bacteria are known to cause deviations from random mating and affect sperm competition (SC) in some of their arthropod hosts. Because these effects could influence the effectiveness of Wolbachia in mosquito population replacement and suppression programs, we developed a theoretical framework to investigate them and we collected relevant data for the wMel infection in Aedes aegypti. Using incompatibility patterns as a measure of mating success of infected versus uninfected mosquitoes, we found some evidence that uninfected males sire more offspring than infected males. However, our theoretical framework suggests that this effect is unlikely to hamper Wolbachia invasion and has only minor effects on population suppression programs. Nevertheless, we suggest that mating effects and SC need to be monitored in an ongoing manner in release programs, given the possibility of ongoing selection for altered mating patterns.
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Affiliation(s)
- Heng Lin Yeap
- Pest, and Environmental Adaptation Research Group (PEARG), School of Bioscience, Bio21 Institute University of Melbourne, Melbourne, Australia
- Commonwealth Scientific, and Industrial Research Organisation (CSIRO), Black Mountain Laboratories, Black Mountain, Canberra, Australia
| | - Nancy Margaret Endersby-Harshman
- Pest, and Environmental Adaptation Research Group (PEARG), School of Bioscience, Bio21 Institute University of Melbourne, Melbourne, Australia
| | - Ary Anthony Hoffmann
- Pest, and Environmental Adaptation Research Group (PEARG), School of Bioscience, Bio21 Institute University of Melbourne, Melbourne, Australia
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60
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Ross PA, Hoffmann AA. Continued Susceptibility of the wMel Wolbachia Infection in Aedes aegypti to Heat Stress Following Field Deployment and Selection. INSECTS 2018; 9:E78. [PMID: 29966368 PMCID: PMC6165456 DOI: 10.3390/insects9030078] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/11/2018] [Revised: 06/27/2018] [Accepted: 06/27/2018] [Indexed: 11/16/2022]
Abstract
Aedes aegypti mosquitoes infected with the wMel strain of Wolbachia are being deployed to control the spread of arboviruses around the world through blockage of viral transmission. Blockage by Wolbachia in some scenarios may be affected by the susceptibility of wMel to cyclical heat stress during mosquito larval development. We therefore evaluated the potential to generate a heat-resistant strain of wMel in Ae. aegypti through artificial laboratory selection and through exposure to field temperatures across multiple generations. To generate an artificially selected strain, wMel-infected females reared under cyclical heat stress were crossed to wMel-infected males reared at 26 °C. The low proportion of larvae that hatched founded the next generation, and this process was repeated for eight generations. The wMel heat-selected strain (wMel-HS) was similar to wMel (unselected) in its ability to induce cytoplasmic incompatibility and restore compatibility when larvae were reared under cyclical heat stress, but wMel-HS adults exhibited reduced Wolbachia densities at 26 °C. To investigate the effects of field exposure, we compared the response of wMel-infected Ae. aegypti collected from Cairns, Australia where the infection has been established for seven years, to a wMel-infected population maintained in the laboratory for approximately 60 generations. Field and laboratory strains of wMel did not differ in their response to cyclical heat stress or in their phenotypic effects at 26 °C. The capacity for the wMel infection in Ae. aegypti to adapt to high temperatures therefore appears limited, and alternative strains may need to be considered for deployment in environments where high temperatures are regularly experienced in mosquito breeding sites.
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Affiliation(s)
- Perran A Ross
- Pest and Environmental Adaptation Research Group, School of BioSciences, Bio21 Institute, The University of Melbourne, Victoria 3010, Australia.
| | - Ary A Hoffmann
- Pest and Environmental Adaptation Research Group, School of BioSciences, Bio21 Institute, The University of Melbourne, Victoria 3010, Australia.
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61
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Marshall JM, Akbari OS. Can CRISPR-Based Gene Drive Be Confined in the Wild? A Question for Molecular and Population Biology. ACS Chem Biol 2018; 13:424-430. [PMID: 29370514 DOI: 10.1021/acschembio.7b00923] [Citation(s) in RCA: 48] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
The recent discovery of CRISPR and its application as a gene editing tool has enabled a range of gene drive systems to be engineered with greater ease. In order for the benefits of this technology to be realized, in some circumstances drive systems should be developed that are capable of both spreading into populations to achieve their desired impact and being recalled in the event of unwanted consequences or public disfavor. We review the performance of three broad categories of drive systems at achieving these goals: threshold-dependent drives, homing-based drive and remediation systems, and temporally self-limiting systems such as daisy-chain drives.
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Affiliation(s)
- John M Marshall
- Divisions of Biostatistics and Epidemiology, School of Public Health, University of California , Berkeley, California 94720, United States
| | - Omar S Akbari
- Section of Cell and Developmental Biology, University of California, San Diego , La Jolla, California 92093, United States of America
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62
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Dorigatti I, McCormack C, Nedjati-Gilani G, Ferguson NM. Using Wolbachia for Dengue Control: Insights from Modelling. Trends Parasitol 2018; 34:102-113. [PMID: 29183717 PMCID: PMC5807169 DOI: 10.1016/j.pt.2017.11.002] [Citation(s) in RCA: 53] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2017] [Revised: 11/01/2017] [Accepted: 11/02/2017] [Indexed: 12/23/2022]
Abstract
Dengue is the most common arboviral infection of humans, responsible for a substantial disease burden across the tropics. Traditional insecticide-based vector-control programmes have limited effectiveness, and the one licensed vaccine has a complex and imperfect efficacy profile. Strains of the bacterium Wolbachia, deliberately introduced into Aedes aegyptimosquitoes, have been shown to be able to spread to high frequencies in mosquito populations in release trials, and mosquitoes infected with these strains show markedly reduced vector competence. Thus, Wolbachia represents an exciting potential new form of biocontrol for arboviral diseases, including dengue. Here, we review how mathematical models give insight into the dynamics of the spread of Wolbachia, the potential impact of Wolbachia on dengue transmission, and we discuss the remaining challenges in evaluation and development.
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Affiliation(s)
- Ilaria Dorigatti
- MRC Centre for Outbreak Analysis and Modelling, Department of Infectious Disease Epidemiology, Imperial College London, London W2 1PG, UK; These authors made equal contributions
| | - Clare McCormack
- MRC Centre for Outbreak Analysis and Modelling, Department of Infectious Disease Epidemiology, Imperial College London, London W2 1PG, UK; These authors made equal contributions
| | - Gemma Nedjati-Gilani
- MRC Centre for Outbreak Analysis and Modelling, Department of Infectious Disease Epidemiology, Imperial College London, London W2 1PG, UK; These authors made equal contributions
| | - Neil M Ferguson
- MRC Centre for Outbreak Analysis and Modelling, Department of Infectious Disease Epidemiology, Imperial College London, London W2 1PG, UK.
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Schmidt TL, Rašić G, Zhang D, Zheng X, Xi Z, Hoffmann AA. Genome-wide SNPs reveal the drivers of gene flow in an urban population of the Asian Tiger Mosquito, Aedes albopictus. PLoS Negl Trop Dis 2017; 11:e0006009. [PMID: 29045401 PMCID: PMC5662242 DOI: 10.1371/journal.pntd.0006009] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2017] [Revised: 10/30/2017] [Accepted: 10/04/2017] [Indexed: 11/24/2022] Open
Abstract
Aedes albopictus is a highly invasive disease vector with an expanding worldwide distribution. Genetic assays using low to medium resolution markers have found little evidence of spatial genetic structure even at broad geographic scales, suggesting frequent passive movement along human transportation networks. Here we analysed genetic structure of Aedes albopictus collected from 12 sample sites in Guangzhou, China, using thousands of genome-wide single nucleotide polymorphisms (SNPs). We found evidence for passive gene flow, with distance from shipping terminals being the strongest predictor of genetic distance among mosquitoes. As further evidence of passive dispersal, we found multiple pairs of full-siblings distributed between two sample sites 3.7 km apart. After accounting for geographical variability, we also found evidence for isolation by distance, previously undetectable in Ae. albopictus. These findings demonstrate how large SNP datasets and spatially-explicit hypothesis testing can be used to decipher processes at finer geographic scales than formerly possible. Our approach can be used to help predict new invasion pathways of Ae. albopictus and to refine strategies for vector control that involve the transformation or suppression of mosquito populations. Aedes albopictus, the Asian Tiger Mosquito, is a highly invasive disease vector with a growing global distribution. Designing strategies to prevent invasion and to control Ae. albopictus populations in invaded regions requires knowledge of how Ae. albopictus disperses. Studies comparing Ae. albopictus populations have found little evidence of genetic structure even between distant populations, suggesting that dispersal along human transportation networks is common. However, a more specific understanding of dispersal processes has been unavailable due to an absence of studies using high-resolution genetic markers. Here we present a study using high-resolution markers, which investigates genetic structure among 152 Ae. albopictus from Guangzhou, China. We found that human transportation networks, particularly shipping terminals, had an influence on genetic structure. We also found genetic distance was correlated with geographical distance, the first such observation in this species. This study demonstrates how high-resolution markers can be used to investigate ecological processes that may otherwise escape detection. We conclude that strategies for controlling Ae. albopictus will have to consider both passive reinvasion along human transportation networks and active reinvasion from neighbouring regions.
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Affiliation(s)
- Thomas L Schmidt
- School of BioSciences, University of Melbourne, Parkville, VIC, Australia
| | - Gordana Rašić
- School of BioSciences, University of Melbourne, Parkville, VIC, Australia
| | - Dongjing Zhang
- Department of Parasitology, Zhongshan School of Medicine, Key Laboratory of Tropical Disease Control, Ministry of Education, Sun Yat-Sen University, Guangzhou, Guangdong, China.,Sun Yat-sen University-Michigan State University Joint Center of Vector Control for Tropical Diseases, Guangzhou, Guangdong, China
| | - Xiaoying Zheng
- Department of Parasitology, Zhongshan School of Medicine, Key Laboratory of Tropical Disease Control, Ministry of Education, Sun Yat-Sen University, Guangzhou, Guangdong, China.,Sun Yat-sen University-Michigan State University Joint Center of Vector Control for Tropical Diseases, Guangzhou, Guangdong, China
| | - Zhiyong Xi
- Sun Yat-sen University-Michigan State University Joint Center of Vector Control for Tropical Diseases, Guangzhou, Guangdong, China.,Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, Michigan, United States of America
| | - Ary A Hoffmann
- School of BioSciences, University of Melbourne, Parkville, VIC, Australia
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