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Barr JS, Martin LE, Tate AT, Hillyer JF. Warmer environmental temperature accelerates aging in mosquitoes, decreasing longevity and worsening infection outcomes. Immun Ageing 2024; 21:61. [PMID: 39261928 PMCID: PMC11389126 DOI: 10.1186/s12979-024-00465-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2024] [Accepted: 09/04/2024] [Indexed: 09/13/2024]
Abstract
BACKGROUND Most insects are poikilotherms and ectotherms, so their body temperature is predicated by environmental temperature. With climate change, insect body temperature is rising, which affects how insects develop, survive, and respond to infection. Aging also affects insect physiology by deteriorating body condition and weakening immune proficiency via senescence. Aging is usually considered in terms of time, or chronological age, but it can also be conceptualized in terms of body function, or physiological age. We hypothesized that warmer temperature decouples chronological and physiological age in insects by accelerating senescence. To investigate this, we reared the African malaria mosquito, Anopheles gambiae, at 27 °C, 30 °C and 32 °C, and measured survival starting at 1-, 5-, 10- and 15-days of adulthood after no manipulation, injury, or a hemocoelic infection with Escherichia coli or Micrococcus luteus. Then, we measured the intensity of an E. coli infection to determine how the interaction between environmental temperature and aging shapes a mosquito's response to infection. RESULTS We demonstrate that longevity declines when a mosquito is infected with bacteria, mosquitoes have shorter lifespans when the temperature is warmer, older mosquitoes are more likely to die, and warmer temperature marginally accelerates the aging-dependent decline in survival. Furthermore, we discovered that E. coli infection intensity increases when the temperature is warmer and with aging, and that warmer temperature accelerates the aging-dependent increase in infection intensity. Finally, we uncovered that warmer temperature affects both bacterial and mosquito physiology. CONCLUSIONS Warmer environmental temperature accelerates aging in mosquitoes, negatively affecting both longevity and infection outcomes. These findings have implications for how insects will serve as pollinators, agricultural pests, and disease vectors in our warming world.
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Affiliation(s)
- Jordyn S Barr
- Department of Biological Sciences, Vanderbilt University, Nashville, TN, USA
| | - Lindsay E Martin
- Department of Biological Sciences, Vanderbilt University, Nashville, TN, USA
| | - Ann T Tate
- Department of Biological Sciences, Vanderbilt University, Nashville, TN, USA
| | - Julián F Hillyer
- Department of Biological Sciences, Vanderbilt University, Nashville, TN, USA.
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2
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Shetty V, Adelman ZN, Slotman MA. Effects of circadian clock disruption on gene expression and biological processes in Aedes aegypti. BMC Genomics 2024; 25:170. [PMID: 38347446 PMCID: PMC10863115 DOI: 10.1186/s12864-024-10078-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2023] [Accepted: 02/01/2024] [Indexed: 02/15/2024] Open
Abstract
BACKGROUND This study explores the impact of disrupting the circadian clock through a Cycle gene knockout (KO) on the transcriptome of Aedes aegypti mosquitoes. The investigation aims to uncover the resulting alterations in gene expression patterns and physiological processes. RESULTS Transcriptome analysis was conducted on Cyc knockout (AeCyc-/-) and wild-type mosquitoes at four time points in a light-dark cycle. The study identified system-driven genes that exhibit rhythmic expression independently of the core clock machinery. Cyc disruption led to altered expression of essential clock genes, affecting metabolic processes, signaling pathways, stimulus responses and immune responses. Notably, gene ontology enrichment of odorant binding proteins, indicating the clock's role in sensory perception. The absence of Cyc also impacted various regulation of metabolic and cell cycle processes was observed in all time points. CONCLUSIONS The intricate circadian regulation in Ae. aegypti encompasses both core clock-driven and system-driven genes. The KO of Cyc gene instigated extensive gene expression changes, impacting various processes, thereby potentially affecting cellular and metabolic functions, immune responses, and sensory perception. The circadian clock's multifaceted involvement in diverse biological processes, along with its role in the mosquito's daily rhythms, forms a nexus that influences the vector's capacity to transmit diseases. These insights shed light on the circadian clock's role in shaping mosquito biology and behavior, opening new avenues for innovative disease control strategies.
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Affiliation(s)
- Vinaya Shetty
- Department of Entomology, Texas A&M University, College station, TX, 77843, USA.
| | - Zach N Adelman
- Department of Entomology, Texas A&M University, College station, TX, 77843, USA
| | - Michel A Slotman
- Department of Entomology, Texas A&M University, College station, TX, 77843, USA
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3
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Llergo JL, Garuti H, Lopez C, Sanchez J, Calvo D. Artificial nighttime lighting impacts Plasmodium falciparum mature stage V gametocytes infectivity in Anopheles stephensi. Malar J 2024; 23:42. [PMID: 38326842 PMCID: PMC10851600 DOI: 10.1186/s12936-024-04866-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2023] [Accepted: 01/30/2024] [Indexed: 02/09/2024] Open
Abstract
BACKGROUND Malaria is one of the most important vector-borne diseases of humans with an estimated 241 million cases worldwide in 2020. As an urban and periurban mosquito species, Anopheles stephensi is exposed to artificial human stimuli like light that can alter many aspects of mosquito behaviour, physiology and metabolism. Therefore, fluctuations in the light environment may influence the host, parasite and/or mosquito biology and hence modulate risk for disease transmission. In this study, the effect of artifitial light at night on mosquito infectivity by Plasmodium falciparum during the first hours of blood digestion was tested. METHODS A total of three independent standard membrane feeding assays were performed to artificially fed septic and aseptic mosquitoes with P. falciparum infected blood. After blood feeding, females were transferred to incubators with different photoperiod cycles, so digestion occurred under day artificial light or dark. At 7 and 16 days post blood feeding, mosquitoes were dissected for midguts and salivary glands, respectively. Percentage of mosquitoes fed, percentage of prevalence and P. falciparum oocyst intensity between septic and aseptic mosquitoes in the two different photoperiod regimes, were compared using a Kruskal-Wallis test followed by a Dunn´s multiple comparison test . RESULTS The exposition of mosquitoes to light after they took an infected blood meal has a negative effect on the successful progression of P. falciparum in the mosquito midgut. Antibiotic treatment significantly incremented the number of oocysts per midgut. Photophase significantly reduced the median oocyst intensity in both septic and aseptic mosquitoes. The percentage of oocyst reduction, understood as the percentage of reduction in the mean oocyst intensity of the parasite in the mosquito midgut between photophase and scotophase, was 51% in the case of aseptic mosquitoes and 80% for septic mosquitoes, both in the photophase condition. CONCLUSION Although there are still many gaps in the understanding of parasite-mosquito interactions, these results support the idea that light can, not only, influence mosquito biting behaviour but also parasite success in the mosquito midgut. Hence, light can be considered an interesting additional mosquito-control strategy to reduce mosquito-borne diseases.
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Affiliation(s)
- Jose Luis Llergo
- Global Health Medicines R&D, GlaxoSmithKline, C/Severo Ochoa 2, Tres Cantos, 28760, Madrid, Spain
| | - Helena Garuti
- Global Health Medicines R&D, GlaxoSmithKline, C/Severo Ochoa 2, Tres Cantos, 28760, Madrid, Spain
| | - Celia Lopez
- Global Health Medicines R&D, GlaxoSmithKline, C/Severo Ochoa 2, Tres Cantos, 28760, Madrid, Spain
| | - Julia Sanchez
- In Vivo Science and Delivery (IVSD), GlaxoSmithKline, C/Severo Ochoa 2, Tres Cantos, 28760, Madrid, Spain
| | - David Calvo
- Global Health Medicines R&D, GlaxoSmithKline, C/Severo Ochoa 2, Tres Cantos, 28760, Madrid, Spain.
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Wiil J, Sørensen JG, Colinet H. Exploring cross-protective effects between cold and immune stress in Drosophila melanogaster. Parasite 2023; 30:54. [PMID: 38084935 PMCID: PMC10714677 DOI: 10.1051/parasite/2023055] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2023] [Accepted: 11/12/2023] [Indexed: 12/18/2023] Open
Abstract
It is well established that environmental and biotic stressors like temperature and pathogens/parasites are essential for the life of small ectotherms. There are complex interactions between cold stress and pathogen infection in insects. Possible cross-protective mechanisms occur between both stressors, suggesting broad connectivity in insect stress responses. In this study, the functional significance of these interactions was tested, as well as the potential role of newly uncovered candidate genes, turandot. This was done using an array of factorial experiments exposing Drosophila melanogaster flies to a combination of different cold stress regimes (acute or chronic) and infections with the parasitic fungus Beauveria bassiana. Following these crossed treatments, phenotypic and molecular responses were assessed by measuring 1) induced cold tolerance, 2) immune resistance to parasitic fungus, and 3) activation of turandot genes. We found various responses in the phenotypic outcomes according to the various treatment combinations with higher susceptibility to infection following cold stress, but also significantly higher acute cold survival in flies that were infected. Regarding molecular responses, we found overexpression of turandot genes in response to most treatments, suggesting reactivity to both cold and infection. Moreover, maximum peak expressions were distinctly observed in the combined treatments (infection plus cold), indicating a marked synergistic effect of the stressors on turandot gene expression patterns. These results reflect the great complexity of cross-tolerance reactions between infection and abiotic stress, but could also shed light on the mechanisms underlying the activation of these responses.
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Affiliation(s)
- Jakob Wiil
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Université de Rennes, CNRS, ECOBIO [(Écosystèmes, biodiversité, évolution)] – UMR 6553 263 AVE du Général Leclerc 35000 Rennes France
| | | | - Hervé Colinet
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Université de Rennes, CNRS, ECOBIO [(Écosystèmes, biodiversité, évolution)] – UMR 6553 263 AVE du Général Leclerc 35000 Rennes France
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5
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Brown JJ, Pascual M, Wimberly MC, Johnson LR, Murdock CC. Humidity - The overlooked variable in the thermal biology of mosquito-borne disease. Ecol Lett 2023; 26:1029-1049. [PMID: 37349261 DOI: 10.1111/ele.14228] [Citation(s) in RCA: 17] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2022] [Accepted: 04/05/2023] [Indexed: 06/24/2023]
Abstract
Vector-borne diseases cause significant financial and human loss, with billions of dollars spent on control. Arthropod vectors experience a complex suite of environmental factors that affect fitness, population growth and species interactions across multiple spatial and temporal scales. Temperature and water availability are two of the most important abiotic variables influencing their distributions and abundances. While extensive research on temperature exists, the influence of humidity on vector and pathogen parameters affecting disease dynamics are less understood. Humidity is often underemphasized, and when considered, is often treated as independent of temperature even though desiccation likely contributes to declines in trait performance at warmer temperatures. This Perspectives explores how humidity shapes the thermal performance of mosquito-borne pathogen transmission. We summarize what is known about its effects and propose a conceptual model for how temperature and humidity interact to shape the range of temperatures across which mosquitoes persist and achieve high transmission potential. We discuss how failing to account for these interactions hinders efforts to forecast transmission dynamics and respond to epidemics of mosquito-borne infections. We outline future research areas that will ground the effects of humidity on the thermal biology of pathogen transmission in a theoretical and empirical framework to improve spatial and temporal prediction of vector-borne pathogen transmission.
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Affiliation(s)
- Joel J Brown
- Department of Entomology, Cornell University, Ithaca, New York, USA
| | - Mercedes Pascual
- Department of Ecology and Evolution, University of Chicago, Chicago, Illinois, USA
| | - Michael C Wimberly
- Department of Geography and Environmental Sustainability, University of Oklahoma, Norman, Oklahoma, USA
| | - Leah R Johnson
- Department of Statistics, Virginia Polytechnic Institute and State University, Blacksburg, Virginia, USA
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Evans MV, Bhatnagar S, Drake JM, Murdock CC, Rice JL, Mukherjee S. The mismatch of narratives and local ecologies in the everyday governance of water access and mosquito control in an urbanizing community. Health Place 2023; 80:102989. [PMID: 36804681 DOI: 10.1016/j.healthplace.2023.102989] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/04/2022] [Revised: 01/05/2023] [Accepted: 02/06/2023] [Indexed: 02/18/2023]
Abstract
Mosquito-borne disease presents a significant threat to urban populations, but risk can be uneven across a city due to underlying environmental patterns. Urban residents rely on social and economic processes to control the environment and mediate disease risk, a phenomenon known as everyday governance. We studied how households employed everyday governance of urban infrastructure relevant to mosquito-borne disease in Bengaluru, India to examine if and how inequalities in everyday governance manifest in differences in mosquito control. We found that governance mechanisms differed for water access and mosquitoes. Economic and social capital served different roles for each, influenced by global narratives of water and vector control.
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Affiliation(s)
- M V Evans
- MIVEGEC, Univ. Montpellier, CNRS, IRD, Montpellier, France; Odum School of Ecology, University of Georgia, Athens, GA, USA; Center for Ecology of Infectious Diseases, University of Georgia, Athens, GA, USA.
| | - S Bhatnagar
- Observatoire de Genève, Université de Genève, Sauverny, Switzerland; School of Arts and Sciences, Azim Premji University, Bengaluru, Karnataka, India
| | - J M Drake
- Odum School of Ecology, University of Georgia, Athens, GA, USA; Center for Ecology of Infectious Diseases, University of Georgia, Athens, GA, USA
| | - C C Murdock
- Odum School of Ecology, University of Georgia, Athens, GA, USA; Center for Ecology of Infectious Diseases, University of Georgia, Athens, GA, USA; Department of Entomology, College of Agriculture and Life Sciences, Cornell University, Ithaca, NY, USA; Cornell Institute of Host-Microbe Interactions and Disease, Cornell University, Ithaca, NY, USA; Northeast Regional Center for Excellence in Vector-borne Diseases, Cornell University, Ithaca, NY, USA
| | - J L Rice
- Department of Geography, University of Georgia, Athens, GA, USA
| | - S Mukherjee
- School of Arts and Sciences, Azim Premji University, Bengaluru, Karnataka, India; Biological and Life Sciences Division, School of Arts and Sciences, Ahmedabad University, Ahmedabad, Gujarat, India
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7
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Jian XY, Jiang YT, Wang M, Jia N, Cai T, Xing D, Li CX, Zhao TY, Guo XX, Wu JH. Effects of constant temperature and daily fluctuating temperature on the transovarial transmission and life cycle of Aedes albopictus infected with Zika virus. Front Microbiol 2023; 13:1075362. [PMID: 36687634 PMCID: PMC9845868 DOI: 10.3389/fmicb.2022.1075362] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2022] [Accepted: 12/06/2022] [Indexed: 01/05/2023] Open
Abstract
Introduction Numerous studies on the mosquito life cycle and transmission efficacy were performed under constant temperatures. Mosquito in wild, however, is not exposed to constant temperature but is faced with temperature variation on a daily basis. Methods In the present study, the mosquito life cycle and Zika virus transmission efficiency were conducted at daily fluctuating temperatures and constant temperatures. Aedes albopictus was infected with the Zika virus orally. The oviposition and survival of the infected mosquitoes and hatching rate, the growth cycle of larvae at each stage, and the infection rate (IR) of the progeny mosquitoes were performed at two constant temperatures (23°C and 31°C) and a daily temperature range (DTR, 23-31°C). Results It showed that the biological parameters of mosquitoes under DTR conditions were significantly different from that under constant temperatures. Mosquitoes in DTR survived longer, laid more eggs (mean number: 36.5 vs. 24.2), and had a higher hatching rate (72.3% vs. 46.5%) but a lower pupation rate (37.9% vs. 81.1%) and emergence rate (72.7% vs. 91.7%) than that in the high-temperature group (constant 31°C). When compared to the low-temperature group (constant 23°C), larvae mosquitoes in DTR developed faster (median days: 9 vs. 23.5) and adult mosquitoes carried higher Zika viral RNA load (median log10 RNA copies/μl: 5.28 vs. 3.86). However, the temperature or temperature pattern has no effect on transovarial transmission. Discussion Those results indicated that there are significant differences between mosquito development and reproductive cycles under fluctuating and constant temperature conditions, and fluctuating temperature is more favorable for mosquitos' survival and reproduction. The data would support mapping and predicting the distribution of Aedes mosquitoes in the future and establishing an early warning system for Zika virus epidemics.
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Affiliation(s)
- Xian-yi Jian
- The Key and Characteristic Laboratory of Modern Pathogen Biology, School of Basic Medical Sciences, Guizhou Medical University, Guiyang, China,State Key Laboratory of Pathogens and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Yu-ting Jiang
- State Key Laboratory of Pathogens and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Miao Wang
- State Key Laboratory of Pathogens and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Nan Jia
- State Key Laboratory of Pathogens and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Tong Cai
- State Key Laboratory of Pathogens and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Dan Xing
- State Key Laboratory of Pathogens and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Chun-xiao Li
- State Key Laboratory of Pathogens and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Tong-yan Zhao
- State Key Laboratory of Pathogens and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China,Tong-yan Zhao ✉
| | - Xiao-xia Guo
- State Key Laboratory of Pathogens and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China,Xiao-xia Guo ✉
| | - Jia-hong Wu
- The Key and Characteristic Laboratory of Modern Pathogen Biology, School of Basic Medical Sciences, Guizhou Medical University, Guiyang, China,*Correspondence: Jia-hong Wu ✉
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8
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Habtewold T, Tapanelli S, Masters EKG, Windbichler N, Christophides GK. The circadian clock modulates Anopheles gambiae infection with Plasmodium falciparum. PLoS One 2022; 17:e0278484. [PMID: 36454885 PMCID: PMC9714873 DOI: 10.1371/journal.pone.0278484] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2022] [Accepted: 11/16/2022] [Indexed: 12/03/2022] Open
Abstract
Key behaviours, physiologies and gene expressions in Anopheles mosquitoes impact the transmission of Plasmodium. Such mosquito factors are rhythmic to closely follow diel rhythms. Here, we set to explore the impact of the mosquito circadian rhythm on the tripartite interaction between the vector, the parasite and the midgut microbiota, and investigate how this may affect the parasite infection outcomes. We assess Plasmodium falciparum infection prevalence and intensity, as a proxy for gametocyte infectivity, in Anopheles gambiae mosquitoes that received a gametocyte-containing bloodfeed and measure the abundance of the midgut microbiota at different times of the mosquito rearing light-dark cycle. Gametocyte infectivity is also compared in mosquitoes reared and maintained under a reversed light-dark regime. The effect of the circadian clock on the infection outcome is also investigated through silencing of the CLOCK gene that is central in the regulation of animal circadian rhythms. The results reveal that the A. gambiae circadian cycle plays a key role in the intensity of infection of P. falciparum gametocytes. We show that parasite gametocytes are more infectious during the night-time, where standard membrane feeding assays (SMFAs) at different time points in the mosquito natural circadian rhythm demonstrate that gametocytes are more infectious when ingested at midnight than midday. When mosquitoes were cultured under a reversed light/dark regime, disrupting their natural physiological homeostasis, and infected with P. falciparum at evening hours, the infection intensity and prevalence were significantly decreased. Similar results were obtained in mosquitoes reared under the standard light/dark regime upon silencing of CLOCK, a key regulator of the circadian rhythm, highlighting the importance of the circadian rhythm for the mosquito vectorial capacity. At that time, the mosquito midgut microbiota load is significantly reduced, while the expression of lysozyme C-1 (LYSC-1) is elevated, which is involved in both the immune response and microbiota digestion. We conclude that the tripartite interactions between the mosquito vector, the malaria parasite and the mosquito gut microbiota are finely tuned to support and maintain malaria transmission. Our data add to the knowledge framework required for designing appropriate and biologically relevant SMFA protocols.
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Affiliation(s)
- Tibebu Habtewold
- Department of Life Sciences, Imperial College London, London, United Kingdom
| | - Sofia Tapanelli
- Department of Life Sciences, Imperial College London, London, United Kingdom
| | - Ellen K. G. Masters
- Department of Life Sciences, Imperial College London, London, United Kingdom
| | - Nikolai Windbichler
- Department of Life Sciences, Imperial College London, London, United Kingdom
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9
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Agyekum TP, Arko-Mensah J, Botwe PK, Hogarh JN, Issah I, Dadzie SK, Dwomoh D, Billah MK, Robins T, Fobil JN. Relationship between temperature and Anopheles gambiae sensu lato mosquitoes' susceptibility to pyrethroids and expression of metabolic enzymes. Parasit Vectors 2022; 15:163. [PMID: 35527275 PMCID: PMC9080126 DOI: 10.1186/s13071-022-05273-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2022] [Accepted: 04/01/2022] [Indexed: 11/29/2022] Open
Abstract
Background Malaria remains one of the most devastating diseases globally, and the control of mosquitoes as the vector is mainly dependent on chemical insecticides. Elevated temperatures associated with future warmer climates could affect mosquitoes' metabolic enzyme expression and increase insecticide resistance, making vector control difficult. Understanding how mosquito rearing temperatures influence their susceptibility to insecticide and expression of metabolic enzymes could aid in the development of novel tools and strategies to control mosquitoes in a future warmer climate. This study evaluated the effects of temperature on the susceptibility of Anopheles gambiae sensu lato (s.l.) mosquitoes to pyrethroids and their expression of metabolic enzymes. Methods Anopheles gambiae s.l. eggs obtained from laboratory-established colonies were reared under eight temperature regimes (25, 28, 30, 32, 34, 36, 38, and 40 °C). Upon adult emergence, 3- to 5-day-old female non-blood-fed mosquitoes were used for susceptibility tests following the World Health Organization (WHO) bioassay protocol. Batches of 20–25 mosquitoes from each temperature regime (25–34 °C) were exposed to two pyrethroid insecticides (0.75% permethrin and 0.05% deltamethrin). In addition, the levels of four metabolic enzymes (α-esterase, β-esterase, glutathione S-transferase [GST], and mixed-function oxidase [MFO]) were examined in mosquitoes that were not exposed and those that were exposed to pyrethroids. Results Mortality in An. gambiae s.l. mosquitoes exposed to deltamethrin and permethrin decreased at temperatures above 28 °C. In addition, mosquitoes reared at higher temperatures were more resistant and had more elevated enzyme levels than those raised at low temperatures. Overall, mosquitoes that survived after being exposed to pyrethroids had higher levels of metabolic enzymes than those that were not exposed to pyrethroids. Conclusions This study provides evidence that elevated temperatures decreased An. gambiae s.l. mosquitoes' susceptibility to pyrethroids and increased the expression of metabolic enzymes. This evidence suggests that elevated temperatures projected in a future warmer climate could increase mosquitoes' resistance to insecticides and complicate malaria vector control measures. This study therefore provides vital information, and suggests useful areas of future research, on the effects of temperature variability on mosquitoes that could guide vector control measures in a future warmer climate. Graphical Abstract ![]()
Supplementary Information The online version contains supplementary material available at 10.1186/s13071-022-05273-z.
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Affiliation(s)
- Thomas Peprah Agyekum
- Department of Biological, Environmental and Occupational Health Sciences, School of Public Health, University of Ghana, P.O. Box L.G. 13, Accra, Ghana.
| | - John Arko-Mensah
- Department of Biological, Environmental and Occupational Health Sciences, School of Public Health, University of Ghana, P.O. Box L.G. 13, Accra, Ghana
| | - Paul Kingsley Botwe
- Department of Biological, Environmental and Occupational Health Sciences, School of Public Health, University of Ghana, P.O. Box L.G. 13, Accra, Ghana
| | - Jonathan Nartey Hogarh
- Department of Environmental Science, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana
| | - Ibrahim Issah
- Department of Biological, Environmental and Occupational Health Sciences, School of Public Health, University of Ghana, P.O. Box L.G. 13, Accra, Ghana
| | - Samuel Kweku Dadzie
- Parasitology Department, Noguchi Memorial Institute for Medical Research (NMIMR), University of Ghana, P.O. Box LG 581, Accra, Ghana
| | - Duah Dwomoh
- Department of Biostatistics, School of Public Health, College of Health Sciences, University of Ghana, Legon, Ghana
| | - Maxwell Kelvin Billah
- Department of Animal Biology and Conservation Science, University of Ghana, P.O. Box L.G. 67, Accra, Ghana
| | - Thomas Robins
- Department of Environmental Health Sciences, University of Michigan, 1415 Washington Heights, Ann Arbor, MI, 48109, USA
| | - Julius Najah Fobil
- Department of Biological, Environmental and Occupational Health Sciences, School of Public Health, University of Ghana, P.O. Box L.G. 13, Accra, Ghana
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10
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Namias A, Jobe NB, Paaijmans KP, Huijben S. The need for practical insecticide-resistance guidelines to effectively inform mosquito-borne disease control programs. eLife 2021; 10:e65655. [PMID: 34355693 PMCID: PMC8346280 DOI: 10.7554/elife.65655] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2020] [Accepted: 07/26/2021] [Indexed: 11/13/2022] Open
Abstract
Monitoring local mosquito populations for insecticide resistance is critical for effective vector-borne disease control. However, widely used phenotypic assays, which are designed to monitor the emergence and spread of insecticide resistance (technical resistance), do not translate well to the efficacy of vector control products to suppress mosquito numbers in the field (practical resistance). This is because standard testing conditions such as environmental conditions, exposure dose, and type of substrate differ dramatically from those experienced by mosquitoes under field conditions. In addition, field mosquitoes have considerably different physiological characteristics such as age and blood-feeding status. Beyond this, indirect impacts of insecticide resistance and/or exposure on mosquito longevity, pathogen development, host-seeking behavior, and blood-feeding success impact disease transmission. Given the limited number of active ingredients currently available and the observed discordance between resistance and disease transmission, we conclude that additional testing guidelines are needed to determine practical resistance-the efficacy of vector control tools under relevant local conditions- in order to obtain programmatic impact.
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Affiliation(s)
- Alice Namias
- Département de Biologie, Ecole Normale Supérieure, PSL Research University, Paris, France
- Institut des Sciences de l'Evolution de Montpellier (ISEM), Université de Montpellier, CNRS, IRD, EPHE, Montpellier, France
| | - Ndey Bassin Jobe
- Center for Evolution and Medicine, School of Life Sciences, Arizona State University, Life Sciences C, Tempe, United States
| | - Krijn Petrus Paaijmans
- Center for Evolution and Medicine, School of Life Sciences, Arizona State University, Life Sciences C, Tempe, United States
- The Biodesign Center for Immunotherapy, Vaccines and Virotherapy, Arizona State University, Biodesign Institute, Tempe, United States
- ISGlobal, Carrer del Rosselló, Barcelona, Spain
- Centro de Investigação em Saúde de Manhiça (CISM), Distrito da Manhiça, Mozambique
| | - Silvie Huijben
- Center for Evolution and Medicine, School of Life Sciences, Arizona State University, Life Sciences C, Tempe, United States
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11
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Agyekum TP, Botwe PK, Arko-Mensah J, Issah I, Acquah AA, Hogarh JN, Dwomoh D, Robins TG, Fobil JN. A Systematic Review of the Effects of Temperature on Anopheles Mosquito Development and Survival: Implications for Malaria Control in a Future Warmer Climate. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2021; 18:7255. [PMID: 34299706 PMCID: PMC8306597 DOI: 10.3390/ijerph18147255] [Citation(s) in RCA: 32] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/02/2021] [Revised: 06/17/2021] [Accepted: 06/22/2021] [Indexed: 12/17/2022]
Abstract
The rearing temperature of the immature stages can have a significant impact on the life-history traits and the ability of adult mosquitoes to transmit diseases. This review assessed published evidence of the effects of temperature on the immature stages, life-history traits, insecticide susceptibility, and expression of enzymes in the adult Anopheles mosquito. Original articles published through 31 March 2021 were systematically retrieved from Scopus, Google Scholar, Science Direct, PubMed, ProQuest, and Web of Science databases. After applying eligibility criteria, 29 studies were included. The review revealed that immature stages of An. arabiensis were more tolerant (in terms of survival) to a higher temperature than An. funestus and An. quadriannulatus. Higher temperatures resulted in smaller larval sizes and decreased hatching and pupation time. The development rate and survival of An. stephensi was significantly reduced at a higher temperature than a lower temperature. Increasing temperatures decreased the longevity, body size, length of the gonotrophic cycle, and fecundity of Anopheles mosquitoes. Higher rearing temperatures increased pyrethroid resistance in adults of the An. arabiensis SENN DDT strain, and increased pyrethroid tolerance in the An. arabiensis SENN strain. Increasing temperature also significantly increased Nitric Oxide Synthase (NOS) expression and decreased insecticide toxicity. Both extreme low and high temperatures affect Anopheles mosquito development and survival. Climate change could have diverse effects on Anopheles mosquitoes. The sensitivities of Anopeheles mosquitoes to temperature differ from species to species, even among the same complex. Notwithstanding, there seem to be limited studies on the effects of temperature on adult life-history traits of Anopheles mosquitoes, and more studies are needed to clarify this relationship.
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Affiliation(s)
- Thomas P. Agyekum
- Department of Biological, Environmental and Occupational Health Sciences, School of Public Health, University of Ghana, Accra 00233, Ghana; (P.K.B.); (J.A.-M.); (I.I.); (A.A.A.); (J.N.F.)
| | - Paul K. Botwe
- Department of Biological, Environmental and Occupational Health Sciences, School of Public Health, University of Ghana, Accra 00233, Ghana; (P.K.B.); (J.A.-M.); (I.I.); (A.A.A.); (J.N.F.)
| | - John Arko-Mensah
- Department of Biological, Environmental and Occupational Health Sciences, School of Public Health, University of Ghana, Accra 00233, Ghana; (P.K.B.); (J.A.-M.); (I.I.); (A.A.A.); (J.N.F.)
| | - Ibrahim Issah
- Department of Biological, Environmental and Occupational Health Sciences, School of Public Health, University of Ghana, Accra 00233, Ghana; (P.K.B.); (J.A.-M.); (I.I.); (A.A.A.); (J.N.F.)
| | - Augustine A. Acquah
- Department of Biological, Environmental and Occupational Health Sciences, School of Public Health, University of Ghana, Accra 00233, Ghana; (P.K.B.); (J.A.-M.); (I.I.); (A.A.A.); (J.N.F.)
| | - Jonathan N. Hogarh
- Department of Environmental Science, Kwame Nkrumah University of Science and Technology, Kumasi 00233, Ghana;
| | - Duah Dwomoh
- Department of Biostatistics, School of Public Health, College of Health Sciences, University of Ghana, Accra 00233, Ghana;
| | - Thomas G. Robins
- Department of Environmental Health Sciences, University of Michigan, 1415 Washington Heights, Ann Arbor, MI 48109, USA;
| | - Julius N. Fobil
- Department of Biological, Environmental and Occupational Health Sciences, School of Public Health, University of Ghana, Accra 00233, Ghana; (P.K.B.); (J.A.-M.); (I.I.); (A.A.A.); (J.N.F.)
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12
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Huang X, Huang D, Liang Y, Zhang L, Yang G, Liu B, Peng Y, Deng W, Dong L. A new protocol for absolute quantification of haemosporidian parasites in raptors and comparison with current assays. Parasit Vectors 2020; 13:354. [PMID: 32680557 PMCID: PMC7368712 DOI: 10.1186/s13071-020-04195-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2020] [Accepted: 06/17/2020] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Accurate quantification of infection intensity is essential to estimate infection patterns of avian haemosporidian parasites in order to understand the evolution of host-parasite associations. Traditional microscopy is cost-effective but requires high-quality blood smears and considerable experience, while the widely used semi-quantitative qPCR methods are mostly employed with ideal, laboratory-based golden samples and standard curves, which may limit the comparison of parasitemia from different laboratories. METHODS Here we present a digital droplet PCR (ddPCR) protocol for absolute quantification of avian haemosporidians in raptors. Novel primers were designed that target a conserved fragment of a rRNA region of the mitochondrial genome of the parasites. Sensitivity and repeatability were evaluated compared to qPCR and other assays. RESULTS This ddPCR assay enables accurate quantification of haemosporidian parasites belonging to Plasmodium, Haemoproteus and Leucocytozoon with minimum infection quantities of 10-5 (i.e. one parasite copy in 105 host genomes) without the use of standard curves. Quantities assessed by ddPCR were more accurate than qPCR using the same primers through reduction of non-specific amplification in low-intensity samples. The ddPCR technique was more consistent among technical duplicates and reactions, especially when infection intensities were low, and this technique demonstrated equal sensitivity with high correspondence (R2 = 0.97) compared to the widely used qPCR assay. Both ddPCR and qPCR identified more positive samples than the standard nested PCR protocol for the cytb gene used for barcoding avian haemosporidians. CONCLUSIONS We developed a novel ddPCR assay enabling accurate quantification of avian haemosporidians without golden samples or standard curves. This assay can be used as a robust method for investigating infection patterns in different host-parasite assemblages and can facilitate the comparison of results from different laboratories.
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Affiliation(s)
- Xi Huang
- College of Life Sciences, Beijing Normal University, Beijing, China.,MOE Key Laboratory for Biodiversity Sciences and Ecological Engineering, Beijing Normal University, Beijing, China
| | - Di Huang
- College of Life Sciences, Beijing Normal University, Beijing, China
| | - Yuge Liang
- College of Life Sciences, Beijing Normal University, Beijing, China
| | - Linlin Zhang
- College of Life Sciences, Beijing Normal University, Beijing, China
| | - Guocheng Yang
- College of Life Sciences, Beijing Normal University, Beijing, China
| | - Boye Liu
- Shaanxi Institute of Zoology, Xi'an, China
| | - Yangyang Peng
- College of Life Sciences, Beijing Normal University, Beijing, China
| | - Wenhong Deng
- College of Life Sciences, Beijing Normal University, Beijing, China. .,MOE Key Laboratory for Biodiversity Sciences and Ecological Engineering, Beijing Normal University, Beijing, China.
| | - Lu Dong
- College of Life Sciences, Beijing Normal University, Beijing, China. .,MOE Key Laboratory for Biodiversity Sciences and Ecological Engineering, Beijing Normal University, Beijing, China.
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13
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Ferreira PG, Tesla B, Horácio ECA, Nahum LA, Brindley MA, de Oliveira Mendes TA, Murdock CC. Temperature Dramatically Shapes Mosquito Gene Expression With Consequences for Mosquito-Zika Virus Interactions. Front Microbiol 2020; 11:901. [PMID: 32595607 PMCID: PMC7303344 DOI: 10.3389/fmicb.2020.00901] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2019] [Accepted: 04/16/2020] [Indexed: 12/20/2022] Open
Abstract
Vector-borne flaviviruses are emerging threats to human health. For successful transmission, the virus needs to efficiently enter mosquito cells and replicate within and escape several tissue barriers while mosquitoes elicit major transcriptional responses to flavivirus infection. This process will be affected not only by the specific mosquito-pathogen pairing but also by variation in key environmental variables such as temperature. Thus far, few studies have examined the molecular responses triggered by temperature and how these responses modify infection outcomes, despite substantial evidence showing strong relationships between temperature and transmission in a diversity of systems. To define the host transcriptional changes associated with temperature variation during the early infection process, we compared the transcriptome of mosquito midgut samples from mosquitoes exposed to Zika virus (ZIKV) and non-exposed mosquitoes housed at three different temperatures (20, 28, and 36°C). While the high-temperature samples did not show significant changes from those with standard rearing conditions (28°C) 48 h post-exposure, the transcriptome profile of mosquitoes housed at 20°C was dramatically different. The expression of genes most altered by the cooler temperature involved aspects of blood-meal digestion, ROS metabolism, and mosquito innate immunity. Further, we did not find significant differences in the viral RNA copy number between 24 and 48 h post-exposure at 20°C, suggesting that ZIKV replication is limited by cold-induced changes to the mosquito midgut environment. In ZIKV-exposed mosquitoes, vitellogenin, a lipid carrier protein, was most up-regulated at 20°C. Our results provide a deeper understanding of the temperature-triggered transcriptional changes in Aedes aegypti and can be used to further define the molecular mechanisms driven by environmental temperature variation.
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Affiliation(s)
| | - Blanka Tesla
- Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, GA, United States
| | - Elvira Cynthia Alves Horácio
- René Rachou Institute, Oswaldo Cruz Foundation, Belo Horizonte, Brazil.,Department of Genetics, Ecology and Evolution, Institute of Biological Sciences, Federal University of Minas Gerais, Belo Horizonte, Brazil
| | - Laila Alves Nahum
- René Rachou Institute, Oswaldo Cruz Foundation, Belo Horizonte, Brazil.,Department of Genetics, Ecology and Evolution, Institute of Biological Sciences, Federal University of Minas Gerais, Belo Horizonte, Brazil.,Promove College of Technology, Belo Horizonte, Brazil
| | - Melinda Ann Brindley
- Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, GA, United States.,Department of Population Health, College of Veterinary Medicine, University of Georgia, Athens, GA, United States.,Center for Vaccines and Immunology, University of Georgia, Athens, GA, United States
| | | | - Courtney Cuinn Murdock
- Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, GA, United States.,Center for Vaccines and Immunology, University of Georgia, Athens, GA, United States.,Odum School of Ecology, University of Georgia, Athens, GA, United States.,Center for the Ecology of Infectious Diseases, University of Georgia, Athens, GA, United States.,Center for Emerging and Global Tropical Diseases, University of Georgia, Athens, GA, United States.,River Basin Center, University of Georgia, Athens, GA, United States.,Department of Entomology, College of Agriculture and Life Sciences, Cornell University, Ithaca, NY, United States
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14
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Suh E, Grossman MK, Waite JL, Dennington NL, Sherrard-Smith E, Churcher TS, Thomas MB. The influence of feeding behaviour and temperature on the capacity of mosquitoes to transmit malaria. Nat Ecol Evol 2020; 4:940-951. [PMID: 32367033 PMCID: PMC7334094 DOI: 10.1038/s41559-020-1182-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2019] [Accepted: 03/20/2020] [Indexed: 12/23/2022]
Abstract
Insecticide-treated bed nets reduce malaria transmission by limiting contact between mosquito vectors and human hosts when mosquitoes feed during the night. However, malaria vectors can also feed in the early evening and in the morning when people are not protected. Here, we explored how the timing of blood feeding interacts with environmental temperature to influence the capacity of Anopheles mosquitoes to transmit the human malaria parasite Plasmodium falciparum. In laboratory experiments, we found no effect of biting time itself on the proportion of mosquitoes that became infectious (vector competence) at constant temperature. However, when mosquitoes were maintained under more realistic fluctuating temperatures, there was a significant increase in competence for mosquitoes feeding in the evening (18:00), and a significant reduction in competence for those feeding in the morning (06:00), relative to those feeding at midnight (00:00). These effects appear to be due to thermal sensitivity of malaria parasites during the initial stages of parasite development within the mosquito, and the fact that mosquitoes feeding in the evening experience cooling temperatures during the night, whereas mosquitoes feeding in the morning quickly experience warming temperatures that are inhibitory to parasite establishment. A transmission dynamics model illustrates that such differences in competence could have important implications for malaria prevalence, the extent of transmission that persists in the presence of bed nets, and the epidemiological impact of behavioural resistance. These results indicate that the interaction of temperature and feeding behaviour could be a major ecological determinant of the vectorial capacity of malaria mosquitoes.
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Affiliation(s)
- Eunho Suh
- Center for Infectious Disease Dynamics, Department of Entomology, Penn State University, University Park, PA, USA.
| | - Marissa K Grossman
- Center for Infectious Disease Dynamics, Department of Entomology, Penn State University, University Park, PA, USA
| | - Jessica L Waite
- Center for Infectious Disease Dynamics, Department of Entomology, Penn State University, University Park, PA, USA.,Green Mountain Antibodies, Burlington, VT, USA
| | - Nina L Dennington
- Center for Infectious Disease Dynamics, Department of Entomology, Penn State University, University Park, PA, USA
| | - Ellie Sherrard-Smith
- MRC Centre for Global Infectious Disease Analysis, Department of Infectious Disease Epidemiology, Imperial College London, London, UK
| | - Thomas S Churcher
- MRC Centre for Global Infectious Disease Analysis, Department of Infectious Disease Epidemiology, Imperial College London, London, UK
| | - Matthew B Thomas
- Center for Infectious Disease Dynamics, Department of Entomology, Penn State University, University Park, PA, USA
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15
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Ferguson LV, Sinclair BJ. Thermal Variability and Plasticity Drive the Outcome of a Host-Pathogen Interaction. Am Nat 2020; 195:603-615. [DOI: 10.1086/707545] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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16
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Barredo E, DeGennaro M. Not Just from Blood: Mosquito Nutrient Acquisition from Nectar Sources. Trends Parasitol 2020; 36:473-484. [PMID: 32298634 DOI: 10.1016/j.pt.2020.02.003] [Citation(s) in RCA: 72] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2019] [Revised: 02/12/2020] [Accepted: 02/24/2020] [Indexed: 01/01/2023]
Abstract
Anthropophilic female mosquitoes are well known for their strong attraction to human hosts, but plant nectar is a common energy source in their diets. When sugar sources are scarce, female mosquitoes of some species can compensate by taking larger and more frequent blood meals. Male mosquitoes are exclusively dependent on plant nectar or alternative sugar sources. Plant preference is likely driven by an innate attraction that may be enhanced by experience, as mosquitoes learn to recognize available sugar rewards. Nectar-seeking involves the integration of at least three sensory systems: olfaction, vision and taste. The prevention of vector-borne illnesses, the determination of the mosquitoes' ecological role, and the design of efficient sugar-baited traps will all benefit from understanding the molecular basis of nectar-seeking.
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Affiliation(s)
- Elina Barredo
- Department of Biological Sciences and Biomolecular Sciences Institute, Florida International University, Miami, FL, USA
| | - Matthew DeGennaro
- Department of Biological Sciences and Biomolecular Sciences Institute, Florida International University, Miami, FL, USA.
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17
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Meng Q, Wang S, Zhou S, Liu H, Ma X, Zhou X, Liu H, Xu C, Jiang W. Dissecting the m6A methylation affection on afatinib resistance in non-small cell lung cancer. THE PHARMACOGENOMICS JOURNAL 2019; 20:227-234. [DOI: 10.1038/s41397-019-0110-4] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/02/2018] [Revised: 09/11/2019] [Accepted: 10/03/2019] [Indexed: 12/22/2022]
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18
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Thermoregulatory response of Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae) to infection by Beauveria bassiana, and its effect on survivorship and reproductive success. Sci Rep 2019; 9:13625. [PMID: 31541161 PMCID: PMC6754379 DOI: 10.1038/s41598-019-49950-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2018] [Accepted: 07/04/2019] [Indexed: 11/23/2022] Open
Abstract
Behavioral thermoregulation is a defensive strategy employed by some insects to counter infections by parasites and pathogens. Most reported examples of this type of thermoregulatory response involve behavioral fevering. However depending upon the life history of a host-insect and that of the parasite or pathogen, the host may respond by cold-seeking behavior. Thermoregulation is not only ecologically important; it may affect the success of parasites and pathogens as biological control agents. We examined if Frankliniella occidentalis (Pergande) thermoregulates in response to infection by Beauveria bassiana, a fungal pathogen commonly used for biological control. Fungal-infected thrips preferentially moved to cooler areas (~12 °C) while healthy thrips sought out warmer temperatures (~24 °C). This cold-seeking behavior suppressed the growth of B. bassiana in infected thrips, and significantly improved survivorship of infected thrips. At 24 °C, males only survived up to 10 d after infection and females up to 20 d after infection, which was substantially poorer survivorship than that of corresponding healthy individuals. However, individuals of both sexes survived up to 48 d after infection at 12 °C, which was a much less severe reduction in survivorship compared with the effect of B. bassiana infection at 24 °C. The proportion of females among progeny from infected thrips at 12 °C was higher than at 24 °C. Therefore, cold-seeking behavior is beneficial to F. occidentalis when infected by B. bassiana, and its effects should be considered in the use of B. bassiana in biological control programs.
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19
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O’Donnell AJ, Rund SSC, Reece SE. Time-of-day of blood-feeding: effects on mosquito life history and malaria transmission. Parasit Vectors 2019; 12:301. [PMID: 31262362 PMCID: PMC6604169 DOI: 10.1186/s13071-019-3513-9] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2019] [Accepted: 05/17/2019] [Indexed: 12/21/2022] Open
Abstract
BACKGROUND Biological rhythms allow organisms to compartmentalise and coordinate behaviours, physiologies, and cellular processes with the predictable daily rhythms of their environment. There is increasing recognition that the biological rhythms of mosquitoes that vector parasites are important for global health. For example, whether perturbations in blood foraging rhythms as a consequence of vector control measures can undermine disease control. To address this, we explore the impacts of altered timing of blood-feeding on mosquito life history traits and malaria transmission. METHODS We present three experiments in which Anopheles stephensi mosquitoes were fed in the morning or evening on blood that had different qualities, including: (i) chemical-induced or (ii) Plasmodium chabaudi infection-induced anaemia; (iii) Plasmodium berghei infection but no anaemia; or (iv) stemming from hosts at different times of day. We then compared whether time-of-day variation in blood meal characteristics influences mosquito fitness proxies relating to survival and reproduction, and malaria transmission proxies. RESULTS Mosquito lifespan is not influenced by the time-of-day they received a blood meal, but several reproductive metrics are affected, depending on other blood characteristics. Overall, our data suggest that receiving a blood meal in the morning makes mosquitoes more likely to lay eggs, lay slightly sooner and have a larger clutch size. In keeping with previous work, P. berghei infection reduces mosquito lifespan and the likelihood of laying eggs, but time-of-day of blood-feeding does not impact upon these metrics nor on transmission of this parasite. CONCLUSION The time-of-day of blood-feeding does not appear to have major consequences for mosquito fitness or transmission of asynchronous malaria species. If our results from a laboratory colony of mosquitoes living in benign conditions hold for wild mosquitoes, it suggests that mosquitoes have sufficient flexibility in their physiology to cope with changes in biting time induced by evading insecticide-treated bed nets. Future work should consider the impact of multiple feeding cycles and the abiotic stresses imposed by the need to forage for blood during times of day when hosts are not protected by bed nets.
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Affiliation(s)
- Aidan J. O’Donnell
- Institute of Evolutionary Biology, and Institute of Immunology and Infection Research, School of Biological Sciences, University of Edinburgh, Edinburgh, UK
| | - Samuel S. C. Rund
- Department of Biological Sciences, University of Notre Dame, Notre Dame, IN 46556 USA
| | - Sarah E. Reece
- Institute of Evolutionary Biology, and Institute of Immunology and Infection Research, School of Biological Sciences, University of Edinburgh, Edinburgh, UK
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20
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Ferguson L, Beckett N, French MC, Campbell M, Smith T, Adamo S. Sugar intake interacts with temperature to influence reproduction and immunity in adult Culex pipiens mosquitoes. CAN J ZOOL 2019. [DOI: 10.1139/cjz-2018-0129] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Disease transmission by insect vectors will depend on integrated physiological responses to interacting environmental variables. We explored how interactions between temperature and sucrose concentration affected immunity and fecundity, two variables that contribute to vectorial capacity, in Culex pipiens Linnaeus, 1758 mosquitoes. We provided female C. pipiens with either 2% or 20% sucrose and exposed them to low (22 °C), moderate (25 °C), or high (30 °C) temperatures for 8 days. We then measured the strength of the melanization response in one subpopulation of females and the number of eggs laid as a measure of fecundity in another subpopulation. Temperature interacted with diet to weaken immunity under 2% sucrose at 22 and 25 °C. This effect disappeared at 30 °C, suggesting that high temperatures allowed mosquitoes to compensate for the effects of decreased sucrose. Conversely, increasing temperature increased egg production on a diet of 20% sucrose, but heat exposure on a diet of 2% sucrose decreased fecundity. Overall, we suggest that heat exposure requires investment in thermal protection, which may prompt reconfiguration of the immune system and (or) decreased investment in reproduction. Thus, our understanding of the effects of climate change rest on which physiological system we measure and under which combinations of stressors.
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Affiliation(s)
- L.V. Ferguson
- Department of Biology, Acadia University, Wolfville, NS B4P 2R6, Canada
| | - N.H. Beckett
- Department of Biology, Acadia University, Wolfville, NS B4P 2R6, Canada
| | - M.-C. French
- Department of Biology, Acadia University, Wolfville, NS B4P 2R6, Canada
| | - M.J. Campbell
- Department of Biology, Acadia University, Wolfville, NS B4P 2R6, Canada
| | - T.G. Smith
- Department of Biology, Acadia University, Wolfville, NS B4P 2R6, Canada
| | - S.A. Adamo
- Department of Psychology and Neuroscience, Dalhousie University, Halifax, NS B3H 4R2, Canada
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21
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Westwood ML, O'Donnell AJ, de Bekker C, Lively CM, Zuk M, Reece SE. The evolutionary ecology of circadian rhythms in infection. Nat Ecol Evol 2019; 3:552-560. [PMID: 30886375 PMCID: PMC7614806 DOI: 10.1038/s41559-019-0831-4] [Citation(s) in RCA: 50] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2018] [Accepted: 01/30/2019] [Indexed: 01/05/2023]
Abstract
Biological rhythms coordinate organisms' activities with daily rhythms in the environment. For parasites, this includes rhythms in both the external abiotic environment and the within-host biotic environment. Hosts exhibit rhythms in behaviours and physiologies, including immune responses, and parasites exhibit rhythms in traits underpinning virulence and transmission. Yet, the evolutionary and ecological drivers of rhythms in traits underpinning host defence and parasite offence are largely unknown. Here, we explore how hosts use rhythms to defend against infection, why parasites have rhythms and whether parasites can manipulate host clocks to their own ends. Harnessing host rhythms or disrupting parasite rhythms could be exploited for clinical benefit; we propose an interdisciplinary effort to drive this emerging field forward.
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Affiliation(s)
- Mary L Westwood
- Institute of Evolutionary Biology and Institute of Immunology and Infection Research, School of Biological Sciences, University of Edinburgh, Edinburgh, UK.
| | - Aidan J O'Donnell
- Institute of Evolutionary Biology and Institute of Immunology and Infection Research, School of Biological Sciences, University of Edinburgh, Edinburgh, UK
| | | | - Curtis M Lively
- Department of Biology, Indiana University, Bloomington, IL, USA
| | - Marlene Zuk
- Department of Ecology, Evolution and Behavior, University of Minnesota, St. Paul, MN, USA
| | - Sarah E Reece
- Institute of Evolutionary Biology and Institute of Immunology and Infection Research, School of Biological Sciences, University of Edinburgh, Edinburgh, UK
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22
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Ezeakacha NF, Yee DA. The role of temperature in affecting carry-over effects and larval competition in the globally invasive mosquito Aedes albopictus. Parasit Vectors 2019; 12:123. [PMID: 30890161 PMCID: PMC6423813 DOI: 10.1186/s13071-019-3391-1] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2018] [Accepted: 03/08/2019] [Indexed: 11/24/2022] Open
Abstract
Background Ectotherms, like mosquitoes, have evolved specific responses to variation in environmental conditions like temperature, and these responses could confer a fitness benefit or cost when carried-over to different life stages. However, effects of temperature on animals with complex life-cycles often only focus on part of their life-cycle, or only consider how single aspects of life-history may carry over to new stages. Herein we investigated how temperature affects intraspecific larval competition and carry-over effects from larval to adult stages in the widespread invasive Asian tiger mosquito Aedes albopictus. Methods For larval competition, larvae were reared at three densities (10, 20, and 40 individuals) across three source temperatures (21 °C, 27 °C and 34 °C). To test carry-over effects, adult survival was measured for individuals crossed with adult temperatures of 21 °C, 27 °C and 34 °C from the larval density of 20 individuals at each source temperature. Fecundity data also were obtained from mated females. Results For competition, there was a significant interaction between larval density and temperature, with the smallest females, who took the longest to develop, produced in the highest temperatures; density generally accentuated this effect. Regarding carry-over effects, adults exposed to higher temperatures lead to greater differences in fecundity and survival of adult populations. Conclusions Temperature appears to affect life-history of developing larvae under competitive interactions and can also alter adult fitness as the disparity between larval rearing and adult habitat temperatures increases. This has importance for our understanding for how different life-history stages of Ae. albopictus and other vectors of disease may respond to changing climates.
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Affiliation(s)
- Nnaemeka F Ezeakacha
- School of Biological, Environmental, and Earth Sciences, University of Southern Mississippi, Hattiesburg, MS, 39406, USA.,Department of Entomology, Pennsylvania State University, 012A Chemical Ecology Laboratory, University Park, PA, 16802, USA
| | - Donald A Yee
- School of Biological, Environmental, and Earth Sciences, University of Southern Mississippi, Hattiesburg, MS, 39406, USA.
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23
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Kristan M, Abeku TA, Lines J. Effect of environmental variables and kdr resistance genotype on survival probability and infection rates in Anopheles gambiae (s.s.). Parasit Vectors 2018; 11:560. [PMID: 30367663 PMCID: PMC6204000 DOI: 10.1186/s13071-018-3150-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2018] [Accepted: 10/14/2018] [Indexed: 01/16/2023] Open
Abstract
BACKGROUND Environmental factors, especially ambient temperature and relative humidity affect both mosquitoes and malaria parasites. The early part of sporogony is most sensitive and is affected by high temperatures and temperature fluctuation immediately following ingestion of an infectious blood meal. The aim of this study was to explore whether environmental variables such as temperature, together with the presence of the kdr insecticide resistance mutations, have an impact on survival probability and infection rates in wild Anopheles gambiae (s.s.) exposed and unexposed to a pyrethroid insecticide. METHODS Anopheles gambiae (s.s.) were collected as larvae, reared to adults, and fed on blood samples from 42 Plasmodium falciparum-infected local patients at a health facility in mid-western Uganda, then exposed either to nets treated with sub-lethal doses of deltamethrin or to untreated nets. After seven days, surviving mosquitoes were dissected and their midguts examined for oocysts. Prevalence (proportion infected) and intensity of infection (number of oocysts per infected mosquito) were recorded for each group. Mosquito mortality was recorded daily. Temperature and humidity were recorded every 30 minutes throughout the experiments. RESULTS Our findings indicate that apart from the effect of deltamethrin exposure, mean daily temperature during the incubation period, temperature range during the first 24 hours and on day 4 post-infectious feed had a highly significant effect on the risk of infection. Deltamethrin exposure still significantly impaired survival of kdr homozygous mosquitoes, while mean daily temperature and relative humidity during the incubation period independently affected mosquito mortality. Significant differences in survival of resistant genotypes were detected, with the lowest survival recorded in mosquitoes with heterozygote L1014S/L1014F genotype. CONCLUSIONS This study confirmed that the early part of sporogony is most affected by temperature fluctuations, while environmental factors affect mosquito survival. The impact of insecticide resistance on malaria infection and vector survival needs to be assessed separately for mosquitoes with different resistance mechanisms to fully understand its implications for currently available vector control tools and malaria transmission.
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Affiliation(s)
- Mojca Kristan
- Department of Disease Control, London School of Hygiene & Tropical Medicine, London, UK.
| | | | - Jo Lines
- Department of Disease Control, London School of Hygiene & Tropical Medicine, London, UK
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24
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Schneider P, Rund SSC, Smith NL, Prior KF, O'Donnell AJ, Reece SE. Adaptive periodicity in the infectivity of malaria gametocytes to mosquitoes. Proc Biol Sci 2018; 285:rspb.2018.1876. [PMID: 30282657 PMCID: PMC6191691 DOI: 10.1098/rspb.2018.1876] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2018] [Accepted: 09/06/2018] [Indexed: 12/18/2022] Open
Abstract
Daily rhythms in behaviour, physiology and molecular processes are expected to enable organisms to appropriately schedule activities according to consequences of the daily rotation of the Earth. For parasites, this includes capitalizing on periodicity in transmission opportunities and for hosts/vectors, this may select for rhythms in immune defence. We examine rhythms in the density and infectivity of transmission forms (gametocytes) of rodent malaria parasites in the host's blood, parasite development inside mosquito vectors and potential for onwards transmission. Furthermore, we simultaneously test whether mosquitoes exhibit rhythms in susceptibility. We reveal that at night, gametocytes are twice as infective, despite being less numerous in the blood. Enhanced infectiousness at night interacts with mosquito rhythms to increase sporozoite burdens fourfold when mosquitoes feed during their rest phase. Thus, changes in mosquito biting time (owing to bed nets) may render gametocytes less infective, but this is compensated for by the greater mosquito susceptibility.
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Affiliation(s)
- Petra Schneider
- Institute of Evolutionary Biology and Institute of Immunology and Infection Research, School of Biological Sciences, University of Edinburgh, Charlotte Auerbach Road, Edinburgh EH9 3FL, UK
| | - Samuel S. C. Rund
- Institute of Evolutionary Biology and Institute of Immunology and Infection Research, School of Biological Sciences, University of Edinburgh, Charlotte Auerbach Road, Edinburgh EH9 3FL, UK
- Department of Biological Sciences, University of Notre Dame, Notre Dame, IN, USA
| | - Natasha L. Smith
- Institute of Evolutionary Biology and Institute of Immunology and Infection Research, School of Biological Sciences, University of Edinburgh, Charlotte Auerbach Road, Edinburgh EH9 3FL, UK
| | - Kimberley F. Prior
- Institute of Evolutionary Biology and Institute of Immunology and Infection Research, School of Biological Sciences, University of Edinburgh, Charlotte Auerbach Road, Edinburgh EH9 3FL, UK
| | - Aidan J. O'Donnell
- Institute of Evolutionary Biology and Institute of Immunology and Infection Research, School of Biological Sciences, University of Edinburgh, Charlotte Auerbach Road, Edinburgh EH9 3FL, UK
| | - Sarah E. Reece
- Institute of Evolutionary Biology and Institute of Immunology and Infection Research, School of Biological Sciences, University of Edinburgh, Charlotte Auerbach Road, Edinburgh EH9 3FL, UK
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25
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Amuzu HE, Tsyganov K, Koh C, Herbert RI, Powell DR, McGraw EA. Wolbachia enhances insect-specific flavivirus infection in Aedes aegypti mosquitoes. Ecol Evol 2018; 8:5441-5454. [PMID: 29938064 PMCID: PMC6010864 DOI: 10.1002/ece3.4066] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2018] [Revised: 03/08/2018] [Accepted: 03/13/2018] [Indexed: 01/02/2023] Open
Abstract
Mosquitoes transmit a diverse group of human flaviviruses including West Nile, dengue, yellow fever, and Zika viruses. Mosquitoes are also naturally infected with insect-specific flaviviruses (ISFs), a subgroup of the family not capable of infecting vertebrates. Although ISFs are not medically important, they are capable of altering the mosquito's susceptibility to flaviviruses and may alter host fitness. Wolbachia is an endosymbiotic bacterium of insects that when present in mosquitoes limits the replication of co-infecting pathogens, including flaviviruses. Artificially created Wolbachia-infected Aedes aegypti mosquitoes are being released into the wild in a series of trials around the globe with the hope of interrupting dengue and Zika virus transmission from mosquitoes to humans. Our work investigated the effect of Wolbachia on ISF infection in wild-caught Ae. aegypti mosquitoes from field release zones. All field mosquitoes were screened for the presence of ISFs using general degenerate flavivirus primers and their PCR amplicons sequenced. ISFs were found to be common and widely distributed in Ae. aegypti populations. Field mosquitoes consistently had higher ISF infection rates and viral loads compared to laboratory colony material indicating that environmental conditions may modulate ISF infection in Ae. aegypti. Surprisingly, higher ISF infection rates and loads were found in Wolbachia-infected mosquitoes compared to the Wolbachia-free mosquitoes. Our findings demonstrate that the symbiont is capable of manipulating the mosquito virome and that Wolbachia-mediated viral inhibition is not universal for flaviviruses. This may have implications for the Wolbachia-based DENV control strategy if ISFs confer fitness effects or alter mosquito susceptibility to other flaviviruses.
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Affiliation(s)
- Hilaria E. Amuzu
- School of Biological SciencesMonash UniversityClaytonVic.Australia
| | - Kirill Tsyganov
- Monash Bioinformatics PlatformMonash UniversityClaytonVic.Australia
| | - Cassandra Koh
- School of Biological SciencesMonash UniversityClaytonVic.Australia
| | | | - David R. Powell
- Monash Bioinformatics PlatformMonash UniversityClaytonVic.Australia
| | - Elizabeth A. McGraw
- School of Biological SciencesMonash UniversityClaytonVic.Australia
- Department of EntomologyPennsylvania State UniversityUniversity ParkPennsylvania
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26
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Gloria-Soria A, Armstrong PM, Powell JR, Turner PE. Infection rate of Aedes aegypti mosquitoes with dengue virus depends on the interaction between temperature and mosquito genotype. Proc Biol Sci 2018; 284:rspb.2017.1506. [PMID: 28978730 DOI: 10.1098/rspb.2017.1506] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2017] [Accepted: 09/04/2017] [Indexed: 11/12/2022] Open
Abstract
Dengue fever is the most prevalent arthropod-transmitted viral disease worldwide, with endemic transmission restricted to tropical and subtropical regions of different temperature profiles. Temperature is epidemiologically relevant because it affects dengue infection rates in Aedes aegypti mosquitoes, the major vector of the dengue virus (DENV). Aedes aegypti populations are also known to vary in competence for different DENV genotypes. We assessed the effects of mosquito and virus genotype on DENV infection in the context of temperature by challenging Ae. aegypti from two locations in Vietnam, which differ in temperature regimes, with two isolates of DENV-2 collected from the same two localities, followed by incubation at 25, 27 or 32°C for 10 days. Genotyping of the mosquito populations and virus isolates confirmed that each group was genetically distinct. Extrinsic incubation temperature (EIT) and DENV-2 genotype had a direct effect on the infection rate, consistent with previous studies. However, our results show that the EIT impacts the infection rate differently in each mosquito population, indicating a genotype by environment interaction. These results suggest that the magnitude of DENV epidemics may not only depend on the virus and mosquito genotypes present, but also on how they interact with local temperature. This information should be considered when estimating vector competence of local and introduced mosquito populations during disease risk evaluation.
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Affiliation(s)
- A Gloria-Soria
- Department of Ecology and Evolutionary Biology, Yale University, 165 Prospect St. PO Box 208106, New Haven, CT 06520-8106, USA
| | - P M Armstrong
- The Connecticut Agricultural Experiment Station, 123 Huntington St. PO Box 1106, New Haven, CT 06504, USA
| | - J R Powell
- Department of Ecology and Evolutionary Biology, Yale University, 165 Prospect St. PO Box 208106, New Haven, CT 06520-8106, USA
| | - P E Turner
- Department of Ecology and Evolutionary Biology, Yale University, 165 Prospect St. PO Box 208106, New Haven, CT 06520-8106, USA.,Program in Microbiology, Yale School of Medicine, New Haven, CT 06520, USA
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27
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Ohm JR, Baldini F, Barreaux P, Lefevre T, Lynch PA, Suh E, Whitehead SA, Thomas MB. Rethinking the extrinsic incubation period of malaria parasites. Parasit Vectors 2018. [PMID: 29530073 PMCID: PMC5848458 DOI: 10.1186/s13071-018-2761-4] [Citation(s) in RCA: 55] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The time it takes for malaria parasites to develop within a mosquito, and become transmissible, is known as the extrinsic incubation period, or EIP. EIP is a key parameter influencing transmission intensity as it combines with mosquito mortality rate and competence to determine the number of mosquitoes that ultimately become infectious. In spite of its epidemiological significance, data on EIP are scant. Current approaches to estimate EIP are largely based on temperature-dependent models developed from data collected on parasite development within a single mosquito species in the 1930s. These models assume that the only factor affecting EIP is mean environmental temperature. Here, we review evidence to suggest that in addition to mean temperature, EIP is likely influenced by genetic diversity of the vector, diversity of the parasite, and variation in a range of biotic and abiotic factors that affect mosquito condition. We further demonstrate that the classic approach of measuring EIP as the time at which mosquitoes first become infectious likely misrepresents EIP for a mosquito population. We argue for a better understanding of EIP to improve models of transmission, refine predictions of the possible impacts of climate change, and determine the potential evolutionary responses of malaria parasites to current and future mosquito control tools.
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Affiliation(s)
- Johanna R Ohm
- Center for Infectious Disease Dynamics, Pennsylvania State University, University Park, PA, USA.
| | - Francesco Baldini
- Institute of Biodiversity Animal Health and Comparative Medicine, University of Glasgow, Glasgow, Scotland, UK
| | - Priscille Barreaux
- Center for Infectious Disease Dynamics, Pennsylvania State University, University Park, PA, USA
| | - Thierry Lefevre
- MIVEGEC, IRD, CNRS, University of Montpellier, Montpellier, France
| | - Penelope A Lynch
- College of Life and Environmental Sciences, Penryn Campus, University of Exeter, Cornwall, UK
| | - Eunho Suh
- Center for Infectious Disease Dynamics, Pennsylvania State University, University Park, PA, USA
| | - Shelley A Whitehead
- Center for Infectious Disease Dynamics, Pennsylvania State University, University Park, PA, USA
| | - Matthew B Thomas
- Center for Infectious Disease Dynamics, Pennsylvania State University, University Park, PA, USA
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28
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Lefevre T, Ohm J, Dabiré KR, Cohuet A, Choisy M, Thomas MB, Cator L. Transmission traits of malaria parasites within the mosquito: Genetic variation, phenotypic plasticity, and consequences for control. Evol Appl 2017; 11:456-469. [PMID: 29636799 PMCID: PMC5891056 DOI: 10.1111/eva.12571] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2017] [Accepted: 10/23/2017] [Indexed: 12/16/2022] Open
Abstract
Evaluating the risk of emergence and transmission of vector‐borne diseases requires knowledge of the genetic and environmental contributions to pathogen transmission traits. Compared to the significant effort devoted to understanding the biology of malaria transmission from vertebrate hosts to mosquito vectors, the strategies that malaria parasites have evolved to maximize transmission from vectors to vertebrate hosts have been largely overlooked. While determinants of infection success within the mosquito host have recently received attention, the causes of variability for other key transmission traits of malaria, namely the duration of parasite development and its virulence within the vector, as well as its ability to alter mosquito behavior, remain largely unknown. This important gap in our knowledge needs to be bridged in order to obtain an integrative view of the ecology and evolution of malaria transmission strategies. Associations between transmission traits also need to be characterized, as they trade‐offs and constraints could have important implications for understanding the evolution of parasite transmission. Finally, theoretical studies are required to evaluate how genetic and environmental influences on parasite transmission traits can shape malaria dynamics and evolution in response to disease control.
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Affiliation(s)
- Thierry Lefevre
- MIVEGEC, IRD, CNRS University of Montpellier Montpellier France.,Institut de Recherche en Sciences de la Santé (IRSS) Bobo Dioulasso Burkina Faso.,Laboratoire Mixte International sur les Vecteurs (LAMIVECT) Bobo Dioulasso Burkina Faso
| | - Johanna Ohm
- Department of Entomology and Center for Infectious Disease Dynamics Penn State University University Park PA USA
| | - Kounbobr R Dabiré
- Institut de Recherche en Sciences de la Santé (IRSS) Bobo Dioulasso Burkina Faso.,Laboratoire Mixte International sur les Vecteurs (LAMIVECT) Bobo Dioulasso Burkina Faso
| | - Anna Cohuet
- MIVEGEC, IRD, CNRS University of Montpellier Montpellier France
| | - Marc Choisy
- MIVEGEC, IRD, CNRS University of Montpellier Montpellier France.,Oxford University Clinical Research Unit Hanoi Vietnam
| | - Matthew B Thomas
- Department of Entomology and Center for Infectious Disease Dynamics Penn State University University Park PA USA
| | - Lauren Cator
- Grand Challenges in Ecosystems and Environment Imperial College London Ascot UK
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29
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Reece SE, Prior KF, Mideo N. The Life and Times of Parasites: Rhythms in Strategies for Within-host Survival and Between-host Transmission. J Biol Rhythms 2017; 32:516-533. [PMID: 28845736 PMCID: PMC5734377 DOI: 10.1177/0748730417718904] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Biological rhythms are thought to have evolved to enable organisms to organize their activities according to the earth's predictable cycles, but quantifying the fitness advantages of rhythms is challenging and data revealing their costs and benefits are scarce. More difficult still is explaining why parasites that live exclusively within the bodies of other organisms have biological rhythms. Rhythms exist in the development and traits of parasites, in host immune responses, and in disease susceptibility. This raises the possibility that timing matters for how hosts and parasites interact and, consequently, for the severity and transmission of diseases. Here, we take an evolutionary ecological perspective to examine why parasites exhibit biological rhythms and how their rhythms are regulated. Specifically, we examine the adaptive significance (evolutionary costs and benefits) of rhythms for parasites and explore to what extent interactions between hosts and parasites can drive rhythms in infections. That parasites with altered rhythms can evade the effects of control interventions underscores the urgent need to understand how and why parasites exhibit biological rhythms. Thus, we contend that examining the roles of biological rhythms in disease offers innovative approaches to improve health and opens up a new arena for studying host-parasite (and host-parasite-vector) coevolution.
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Affiliation(s)
- Sarah E. Reece
- Institutes of Evolution, Immunology and Infection Research, University of Edinburgh, Edinburgh, UK
- Centre for Immunity, Infection and Evolution, University of Edinburgh, Edinburgh, UK
| | - Kimberley F. Prior
- Institutes of Evolution, Immunology and Infection Research, University of Edinburgh, Edinburgh, UK
| | - Nicole Mideo
- Department of Ecology & Evolutionary Biology, University of Toronto, Toronto, Ontario, Canada
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30
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Liew JW, Fong MY, Lau YL. Quantitative real-time PCR analysis of Anopheles dirus TEP1 and NOS during Plasmodium berghei infection, using three reference genes. PeerJ 2017; 5:e3577. [PMID: 28761783 PMCID: PMC5533154 DOI: 10.7717/peerj.3577] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2017] [Accepted: 06/23/2017] [Indexed: 01/12/2023] Open
Abstract
Quantitative reverse transcription PCR (qRT-PCR) has been an integral part of characterizing the immunity of Anopheles mosquitoes towards Plasmodium invasion. Two anti-Plasmodium factors of Anopheles, thioester-containing protein 1 (TEP1) and nitric oxide synthase (NOS), play a role in the refractoriness of Anopheles towards Plasmodium infection and are generally expressed during infection. However, these are less studied in Anopheles dirus, a dominant malaria vector in Southeast Asia. Furthermore, most studies used a single reference gene for normalization during gene expression analysis without proper validation. This may lead to erroneous quantification of expression levels. Therefore, the present study characterized and investigated the expression profiles of TEP1 and NOS of Anopheles dirus during P. berghei infection. Prior to that, the elongation factor 1-alpha (EF1), actin 1 (Act) and ribosomal protein S7 (S7) genes were validated for their suitability as a set of reference genes. TEP1 and NOS expressions in An. dirus were found to be significantly induced after P. berghei infection.
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Affiliation(s)
- Jonathan W.K. Liew
- Department of Parasitology, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia
| | - Mun Yik Fong
- Department of Parasitology, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia
| | - Yee Ling Lau
- Department of Parasitology, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia
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31
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Fine-scale variation in microclimate across an urban landscape shapes variation in mosquito population dynamics and the potential of Aedes albopictus to transmit arboviral disease. PLoS Negl Trop Dis 2017; 11:e0005640. [PMID: 28558030 PMCID: PMC5466343 DOI: 10.1371/journal.pntd.0005640] [Citation(s) in RCA: 94] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2016] [Revised: 06/09/2017] [Accepted: 05/12/2017] [Indexed: 11/19/2022] Open
Abstract
Most statistical and mechanistic models used to predict mosquito-borne disease transmission incorporate climate drivers of disease transmission by utilizing environmental data collected at geographic scales that are potentially coarser than what mosquito populations may actually experience. Temperature and relative humidity can vary greatly between indoor and outdoor environments, and can be influenced strongly by variation in landscape features. In the Aedes albopictus system, we conducted a proof-of-concept study in the vicinity of the University of Georgia to explore the effects of fine-scale microclimate variation on mosquito life history and vectorial capacity (VC). We placed Ae. albopictus larvae in artificial pots distributed across three replicate sites within three different land uses–urban, suburban, and rural, which were characterized by high, intermediate, and low proportions of impervious surfaces. Data loggers were placed into each larval environment and in nearby vegetation to record daily variation in water and ambient temperature and relative humidity. The number of adults emerging from each pot and their body size and sex were recorded daily. We found mosquito microclimate to significantly vary across the season as well as with land use. Urban sites were in general warmer and less humid than suburban and rural sites, translating into decreased larval survival, smaller body sizes, and lower per capita growth rates of mosquitoes on urban sites. Dengue transmission potential was predicted to be higher in the summer than the fall. Additionally, the effects of land use on dengue transmission potential varied by season. Warm summers resulted in a higher predicted VC on the cooler, rural sites, while warmer, urban sites had a higher predicted VC during the cooler fall season. Environmental factors influence the dynamics of mosquito-borne disease transmission. Most models used to predict mosquito-borne disease transmission incorporate climate data collected at coarser scales than mosquitoes typically experience. Climate conditions can vary greatly between indoor and outdoor environments, and are influenced by landscape features. We conducted a field experiment with the Asian tiger mosquito to explore how microclimate variation across an urban landscape affects mosquito life history and potential to transmit arboviruses, like dengue. We demonstrate that climate conditions captured by weather stations do not reflect relevant mosquito microclimate, and that subtle variation in mean and diurnal ranges of temperature and relative humidity can lead to appreciable variation in key mosquito / pathogen traits that are important for transmission. Our results have implications for statistical and mechanistic models used to predict variation in transmission across seasons, regions, and land uses, but also for building in realistic environmental variation in laboratory work on mosquito-pathogen interactions. Finally, the variation in microclimate we observed across land use was subtle; likely because our study site is a relatively small city. Nevertheless, these translated into considerable differences in mosquito traits and dengue transmission potential, suggesting these effects could be much larger in more expansive cities.
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32
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Novakova E, Woodhams DC, Rodríguez-Ruano SM, Brucker RM, Leff JW, Maharaj A, Amir A, Knight R, Scott J. Mosquito Microbiome Dynamics, a Background for Prevalence and Seasonality of West Nile Virus. Front Microbiol 2017; 8:526. [PMID: 28421042 PMCID: PMC5378795 DOI: 10.3389/fmicb.2017.00526] [Citation(s) in RCA: 75] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2016] [Accepted: 03/13/2017] [Indexed: 11/13/2022] Open
Abstract
Symbiotic microbial communities augment host phenotype, including defense against pathogen carriage and infection. We sampled the microbial communities in 11 adult mosquito host species from six regions in southern Ontario, Canada over 3 years. Of the factors examined, we found that mosquito species was the largest driver of the microbiota, with remarkable phylosymbiosis between host and microbiota. Seasonal shifts of the microbiome were consistently repeated over the 3-year period, while region had little impact. Both host species and seasonal shifts in microbiota were associated with patterns of West Nile virus (WNV) in these mosquitoes. The highest prevalence of WNV, with a seasonal spike each year in August, was in the Culex pipiens/restuans complex, and high WNV prevalence followed a decrease in relative abundance of Wolbachia in this species. Indeed, mean temperature, but not precipitation, was significantly correlated with Wolbachia abundance. This suggests that at higher temperatures Wolbachia abundance is reduced leading to greater susceptibility to WNV in the subsequent generation of C. pipiens/restuans hosts. Different mosquito genera harbored significantly different bacterial communities, and presence or abundance of Wolbachia was primarily associated with these differences. We identified several operational taxonomic units (OTUs) of Wolbachia that drive overall microbial community differentiation among mosquito taxa, locations and timepoints. Distinct Wolbachia OTUs were consistently found to dominate microbiomes of Cx. pipiens/restuans, and of Coquilletidia perturbans. Seasonal fluctuations of several other microbial taxa included Bacillus cereus, Enterococcus, Methylobacterium, Asaia, Pantoea, Acinetobacter johnsonii, Pseudomonas, and Mycoplasma. This suggests that microbiota may explain some of the variation in vector competence previously attributed to local environmental processes, especially because Wolbachia is known to affect carriage of viral pathogens.
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Affiliation(s)
- Eva Novakova
- Faculty of Science, University of South BohemiaCeske Budejovice, Czechia.,Biology Centre of ASCR, Institute of ParasitologyCeske Budejovice, Czechia
| | - Douglas C Woodhams
- Department of Biology, University of Massachusetts BostonBoston, MA, USA
| | | | | | - Jonathan W Leff
- Cooperative Institute for Research in Environmental Sciences, University of ColoradoBoulder, CO, USA.,Department of Ecology and Evolutionary Biology, University of ColoradoBoulder, CO, USA
| | | | - Amnon Amir
- Department of Computer Science and Engineering, Center for Microbiome Innovation, University of California San DiegoLa Jolla, CA, USA
| | - Rob Knight
- Department of Computer Science and Engineering, Center for Microbiome Innovation, University of California San DiegoLa Jolla, CA, USA.,Department of Pediatrics, University of California San DiegoLa Jolla, CA, USA
| | - James Scott
- Sporometrics IncToronto, ON, Canada.,Division of Occupational and Environmental Health, Dalla Lana School of Public Health, University of TorontoToronto, ON, Canada
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33
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Shragai T, Tesla B, Murdock C, Harrington LC. Zika and chikungunya: mosquito-borne viruses in a changing world. Ann N Y Acad Sci 2017; 1399:61-77. [PMID: 28187236 DOI: 10.1111/nyas.13306] [Citation(s) in RCA: 67] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2016] [Revised: 11/21/2016] [Accepted: 12/02/2016] [Indexed: 12/16/2022]
Abstract
The reemergence and growing burden of mosquito-borne virus infections have incited public fear and growing research efforts to understand the mechanisms of infection-associated health outcomes and to provide better approaches for mosquito vector control. While efforts to develop therapeutics, vaccines, and novel genetic mosquito-control technologies are underway, many important underlying ecological questions remain that could significantly enhance our understanding and ability to predict and prevent transmission. Here, we review the current knowledge about the transmission ecology of two recent arbovirus invaders, the chikungunya and Zika viruses. We introduce the viruses and mosquito vectors, highlighting viral biology, historical routes of transmission, and viral mechanisms facilitating rapid global invasion. In addition, we review factors contributing to vector global invasiveness and transmission efficiency. We conclude with a discussion of how human-induced biotic and abiotic environmental changes facilitate mosquito-borne virus transmission, emphasizing critical gaps in understanding. These knowledge gaps are tremendous; much of our data on basic mosquito ecology in the field predate 1960, and the mosquitoes themselves, as well as the world they live in, have substantially changed. A concerted investment in understanding the basic ecology of these vectors, which serve as the main drivers of pathogen transmission in both wildlife and human populations, is now more important than ever.
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Affiliation(s)
- Talya Shragai
- Department of Entomology, Cornell University, Ithaca, New York
| | - Blanka Tesla
- Department of Infectious Diseases and Odum School of Ecology, University of Georgia, Athens, Georgia
| | - Courtney Murdock
- Department of Infectious Diseases and Odum School of Ecology, University of Georgia, Athens, Georgia
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34
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Pietri JE, DeBruhl H, Sullivan W. The rich somatic life of Wolbachia. Microbiologyopen 2016; 5:923-936. [PMID: 27461737 PMCID: PMC5221451 DOI: 10.1002/mbo3.390] [Citation(s) in RCA: 120] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2016] [Revised: 05/24/2016] [Accepted: 05/28/2016] [Indexed: 01/18/2023] Open
Abstract
Wolbachia is an intracellular endosymbiont infecting most arthropod and some filarial nematode species that is vertically transmitted through the maternal lineage. Due to this primary mechanism of transmission, most studies have focused on Wolbachia interactions with the host germline. However, over the last decade many studies have emerged highlighting the prominence of Wolbachia in somatic tissues, implicating somatic tissue tropism as an important aspect of the life history of this endosymbiont. Here, we review our current understanding of Wolbachia-host interactions at both the cellular and organismal level, with a focus on Wolbachia in somatic tissues.
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Affiliation(s)
- Jose E Pietri
- Department of Molecular, Cell & Developmental Biology, University of California, Santa Cruz, California, USA
| | - Heather DeBruhl
- Biological Sciences Department, California Polytechnic State University, San Luis Obispo, California, USA
| | - William Sullivan
- Department of Molecular, Cell & Developmental Biology, University of California, Santa Cruz, California, USA
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35
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Murdock CC, Sternberg ED, Thomas MB. Malaria transmission potential could be reduced with current and future climate change. Sci Rep 2016; 6:27771. [PMID: 27324146 PMCID: PMC4914975 DOI: 10.1038/srep27771] [Citation(s) in RCA: 62] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2015] [Accepted: 05/24/2016] [Indexed: 12/30/2022] Open
Abstract
Several studies suggest the potential for climate change to increase malaria incidence in cooler, marginal transmission environments. However, the effect of increasing temperature in warmer regions where conditions currently support endemic transmission has received less attention. We investigate how increases in temperature from optimal conditions (27 °C to 30 °C and 33 °C) interact with realistic diurnal temperature ranges (DTR: ± 0 °C, 3 °C, and 4.5 °C) to affect the ability of key vector species from Africa and Asia (Anopheles gambiae and An. stephensi) to transmit the human malaria parasite, Plasmodium falciparum. The effects of increasing temperature and DTR on parasite prevalence, parasite intensity, and mosquito mortality decreased overall vectorial capacity for both mosquito species. Increases of 3 °C from 27 °C reduced vectorial capacity by 51–89% depending on species and DTR, with increases in DTR alone potentially halving transmission. At 33 °C, transmission potential was further reduced for An. stephensi and blocked completely in An. gambiae. These results suggest that small shifts in temperature could play a substantial role in malaria transmission dynamics, yet few empirical or modeling studies consider such effects. They further suggest that rather than increase risk, current and future warming could reduce transmission potential in existing high transmission settings.
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Affiliation(s)
- C C Murdock
- Department of Infectious Diseases, College of Veterinary Medicine, Odum School of Ecology, University of Georgia, 260 Veterinary Medicine, 501 D.W. Brookes Drive, Athens GA 30602, USA.,Center for Infectious Disease Dynamics, Department of Entomology, Pennsylvania State University, Merkle Lab, Orchard Road, University Park, PA 16802, USA
| | - E D Sternberg
- Center for Infectious Disease Dynamics, Department of Entomology, Pennsylvania State University, Merkle Lab, Orchard Road, University Park, PA 16802, USA
| | - M B Thomas
- Center for Infectious Disease Dynamics, Department of Entomology, Pennsylvania State University, Merkle Lab, Orchard Road, University Park, PA 16802, USA
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Pamminger T, Steier T, Tragust S. High temperature and temperature variation undermine future disease susceptibility in a population of the invasive garden ant Lasius neglectus. Naturwissenschaften 2016; 103:46. [DOI: 10.1007/s00114-016-1373-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2016] [Revised: 04/17/2016] [Accepted: 05/13/2016] [Indexed: 10/21/2022]
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Daily Rhythms in Mosquitoes and Their Consequences for Malaria Transmission. INSECTS 2016; 7:insects7020014. [PMID: 27089370 PMCID: PMC4931426 DOI: 10.3390/insects7020014] [Citation(s) in RCA: 59] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/22/2015] [Revised: 03/25/2016] [Accepted: 04/06/2016] [Indexed: 11/16/2022]
Abstract
The 24-h day involves cycles in environmental factors that impact organismal fitness. This is thought to select for organisms to regulate their temporal biology accordingly, through circadian and diel rhythms. In addition to rhythms in abiotic factors (such as light and temperature), biotic factors, including ecological interactions, also follow daily cycles. How daily rhythms shape, and are shaped by, interactions between organisms is poorly understood. Here, we review an emerging area, namely the causes and consequences of daily rhythms in the interactions between vectors, their hosts and the parasites they transmit. We focus on mosquitoes, malaria parasites and vertebrate hosts, because this system offers the opportunity to integrate from genetic and molecular mechanisms to population dynamics and because disrupting rhythms offers a novel avenue for disease control.
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Westby KM, Muturi EJ, Juliano SA. How do Nutritional Stress and La Crosse Virus Infection Interact? Tests for Effects on Willingness to Blood Feed and Fecundity in Aedes albopictus (Diptera: Culicidae). JOURNAL OF MEDICAL ENTOMOLOGY 2016; 53:166-71. [PMID: 26477049 PMCID: PMC4723681 DOI: 10.1093/jme/tjv146] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/06/2015] [Accepted: 09/09/2015] [Indexed: 06/05/2023]
Abstract
Evolutionary theory predicts that vector-borne pathogens should have low virulence for their vector because of selection against pathogens that harm the vector sufficiently to reduce transmission. Environmental factors such as nutritional stress can alter vector-pathogen associations by making the vectors more susceptible to pathogens (condition-dependent competence) and vulnerable to the harm caused by pathogen replication (condition-dependent virulence). We tested the hypotheses of condition-dependent competence and condition-dependent virulence by examining the interactive effects of short-term sugar deprivation and exposure to La Crosse virus (LACV) in female Aedes albopictus (Skuse). We predicted that infection status interacts with sugar deprivation to alter willingness to blood feed and fecundity in the second gonotrophic cycle (condition-dependent virulence). Sugar deprivation had no effect on body infection or disseminated infection rates. Infection status, sugar treatment, and their interaction had no effect on fecundity. Mosquitoes that had intermittent access to sugar were significantly more willing to take a second bloodmeal compared with those that had continuous access to sugar. Infection status and the interaction with sugar treatment had no effect on blood-feeding behavior. Thus, we found no evidence of short-term sugar deprivation leading to condition-dependent competence for, or condition-dependent virulence of, LACV in Ae. albopictus.
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Affiliation(s)
- Katie M Westby
- School of Biological Sciences, Illinois State University, Normal, IL 61790-4120 (; ), Current address: Washington University in St. Louis, Tyson Research Center, 6750 Tyson Valley Rd., Eureka, MO 63025,
| | - Ephantus J Muturi
- Illinois Natural History Survey, University of Illinois at Champaign- Urbana, Champaign, IL
| | - Steven A Juliano
- School of Biological Sciences, Illinois State University, Normal, IL 61790-4120 (; )
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Lippens C, Guivier E, Faivre B, Sorci G. Reaction norms of host immunity, host fitness and parasite performance in a mouse--intestinal nematode interaction. Int J Parasitol 2015; 46:133-40. [PMID: 26627846 DOI: 10.1016/j.ijpara.2015.10.003] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2015] [Revised: 10/16/2015] [Accepted: 10/20/2015] [Indexed: 12/22/2022]
Abstract
The outcome of the encounter between a host and a parasite depends on the synergistic effects of the genetics of the two partners and the environment (sensulato) where the interaction takes place. Reaction norms can depict how host and parasite traits vary across environmental ranges for different genotypes. Here, we performed a large scale experiment where three strains of laboratory mice (SJL, BALB/c and CBA) were infected with four doses of the intestinal nematode Heligmosomoides polygyrus. An increasing infective dose can be considered as a proxy for the environment-dependent risk incontracting the infection. We looked at the fitness traits of hosts and parasites, and assessed the underlying immunological functions likely to affect the observed pattern of resistance/susceptibility/tolerance. We found that the infective dose had a strong effect on both host fitness and parasite performance. Interestingly, for most traits, host genotypes did not rank consistently across the increasing infective doses and according to the expected pattern of strain-specific resistance/susceptibility/tolerance. Analyses of cytokine production allowed better understanding of the mechanistic basis underlying variations in fitness-linked traits. The infective dose affected the shape of the reaction norms of the cytokines IL-4, IL-10 and IL-6. Dose-dependent variation in cytokine production explained, moreover, the strain-specific pattern of infection cost, host resistance and parasite performance. As long as the infective dose increased, there was a marked shift towards a pro-inflammatory status in the SJL strain of mice that was positively correlated with cost of the infection and parasite performance. Overall, our study strongly suggests that the notion of host resistance is labile and depends on the environmental conditions where the interaction takes place. Moreover, integrating information on fitness-linked traits and the underlying mechanisms seems essential for a better understanding of host and parasite adaptations across variable environments.
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Affiliation(s)
- Cédric Lippens
- Biogéosciences, CNRS UMR6282, Université de Bourgogne, 6 Bd Gabriel, 21000 Dijon, France.
| | - Emmanuel Guivier
- Biogéosciences, CNRS UMR6282, Université de Bourgogne, 6 Bd Gabriel, 21000 Dijon, France
| | - Bruno Faivre
- Biogéosciences, CNRS UMR6282, Université de Bourgogne, 6 Bd Gabriel, 21000 Dijon, France
| | - Gabriele Sorci
- Biogéosciences, CNRS UMR6282, Université de Bourgogne, 6 Bd Gabriel, 21000 Dijon, France
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Parham PE, Waldock J, Christophides GK, Hemming D, Agusto F, Evans KJ, Fefferman N, Gaff H, Gumel A, LaDeau S, Lenhart S, Mickens RE, Naumova EN, Ostfeld RS, Ready PD, Thomas MB, Velasco-Hernandez J, Michael E. Climate, environmental and socio-economic change: weighing up the balance in vector-borne disease transmission. Philos Trans R Soc Lond B Biol Sci 2015; 370:rstb.2013.0551. [PMID: 25688012 DOI: 10.1098/rstb.2013.0551] [Citation(s) in RCA: 148] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Arguably one of the most important effects of climate change is the potential impact on human health. While this is likely to take many forms, the implications for future transmission of vector-borne diseases (VBDs), given their ongoing contribution to global disease burden, are both extremely important and highly uncertain. In part, this is owing not only to data limitations and methodological challenges when integrating climate-driven VBD models and climate change projections, but also, perhaps most crucially, to the multitude of epidemiological, ecological and socio-economic factors that drive VBD transmission, and this complexity has generated considerable debate over the past 10-15 years. In this review, we seek to elucidate current knowledge around this topic, identify key themes and uncertainties, evaluate ongoing challenges and open research questions and, crucially, offer some solutions for the field. Although many of these challenges are ubiquitous across multiple VBDs, more specific issues also arise in different vector-pathogen systems.
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Affiliation(s)
- Paul E Parham
- Department of Public Health and Policy, Faculty of Health and Life Sciences, University of Liverpool, Liverpool L69 3GL, UK Grantham Institute for Climate Change, Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine, Imperial College London, St Mary's Campus, London W2 1PG, UK
| | - Joanna Waldock
- The Cyprus Institute, Nicosia, Cyprus Imperial College London, London SW7 2AZ, UK
| | | | - Deborah Hemming
- Meteorological Office Hadley Centre, UK Meteorological Office, Fitzroy Road, Exeter, EX1 3PB, UK
| | - Folashade Agusto
- Department of Mathematics, Austin Peay State University, Clarksville, TN 37044, USA
| | - Katherine J Evans
- Oak Ridge National Laboratory, PO Box 2008, Oak Ridge, TN 37831, USA
| | - Nina Fefferman
- Department of Ecology, Evolution and Natural Resources, Rutgers University, New Brunswick, NJ 08901, USA
| | - Holly Gaff
- Department of Biological Sciences, Old Dominium University, Norfolk, VA 23529, USA
| | - Abba Gumel
- Simon A. Levin Mathematical, Computational and Modeling Sciences Center, Arizona State University, Tempe, AZ 85287-1904, USA School of Mathematical and Natural Sciences, Arizona State University, Phoenix, AZ 85069-7100, USA
| | - Shannon LaDeau
- Cary Institute of Ecosystem Studies, PO Box AB, Millbrook, NY 12545-0129, USA
| | - Suzanne Lenhart
- Department of Mathematics, University of Tennessee, Knoxville, TN 37996-1300, USA
| | - Ronald E Mickens
- Department of Physics, Clark Atlanta University, PO Box 172, Atlanta, GA 30314, USA
| | - Elena N Naumova
- Department of Civil and Environmental Engineering, Tufts University School of Engineering, Medford, MA 02155, USA
| | - Richard S Ostfeld
- Cary Institute of Ecosystem Studies, PO Box AB, Millbrook, NY 12545-0129, USA
| | - Paul D Ready
- Department of Disease Control, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, Keppel Street, London WC1E 7HT, UK
| | - Matthew B Thomas
- Department of Entomology, Pennsylvania State University, University Park, PA 16802, USA
| | - Jorge Velasco-Hernandez
- Universidad Nacional Autnoma de Mexico Institute of Mathematics Mexico City, Distrito Federal, Mexico
| | - Edwin Michael
- Department of Biological Sciences, University of Notre Dame, Notre Dame, IN 46556-0369, USA
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Hunt VL, Zhong W, McClure CD, Mlynski DT, Duxbury EML, Keith Charnley A, Priest NK. Cold-seeking behaviour mitigates reproductive losses from fungal infection in Drosophila. J Anim Ecol 2015; 85:178-86. [PMID: 26332860 PMCID: PMC4879349 DOI: 10.1111/1365-2656.12438] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2015] [Accepted: 08/19/2015] [Indexed: 12/26/2022]
Abstract
Animals must tailor their life‐history strategies to suit the prevailing conditions and respond to hazards in the environment. Animals with lethal infections are faced with a difficult choice: to allocate more resources to reproduction and suffer higher mortality or to reduce reproduction with the expectation of enhanced immunity and late‐age reproduction. However, the strategies employed to mediate shifts in life‐history traits are largely unknown. Here, we investigate the temperature preference of the fruit fly, Drosophila melanogaster, during infection with the fungal pathogen, Metarhizium robertsii, and the consequence of temperature preference on life‐history traits. We have measured the temperature preference of fruit flies under different pathogen conditions. We conducted multiple fitness assays of the host and the pathogen under different thermal conditions. From these data, we estimated standard measures of fitness and used age‐specific methodologies to test for the fitness trade‐offs that are thought to underlie differences in life‐history strategy. We found that fungus‐infected fruit flies seek out cooler temperatures, which facilitates an adaptive shift in their life‐history strategy. The colder temperatures preferred by infected animals were detrimental to the pathogen because it increased resistance to infection. But, it did not provide net benefits that were specific to infected animals, as cooler temperatures increased lifetime reproductive success and survival whether or not the animals were infected. Instead, we find that cold‐seeking benefits infected animals by increasing their late‐age reproductive output, at a cost to their early‐age reproductive output. In contrast, naive control flies prefer warmer temperatures that optimize early‐age reproductive, at a cost to reproductive output at late ages. These findings show that infected animals exhibit fundamentally different reproductive strategies than their healthy counterparts. Temperature preference can facilitate shifts in strategy, but not without inevitable trade‐offs.
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Affiliation(s)
- Vicky L Hunt
- Milner Centre for Evolution and Department of Biology and Biochemistry, University of Bath, Claverton Down, Bath, BA2 7AY, UK
| | - Weihao Zhong
- Milner Centre for Evolution and Department of Biology and Biochemistry, University of Bath, Claverton Down, Bath, BA2 7AY, UK
| | - Colin D McClure
- Milner Centre for Evolution and Department of Biology and Biochemistry, University of Bath, Claverton Down, Bath, BA2 7AY, UK
| | - David T Mlynski
- Milner Centre for Evolution and Department of Biology and Biochemistry, University of Bath, Claverton Down, Bath, BA2 7AY, UK
| | - Elizabeth M L Duxbury
- Milner Centre for Evolution and Department of Biology and Biochemistry, University of Bath, Claverton Down, Bath, BA2 7AY, UK
| | - A Keith Charnley
- Milner Centre for Evolution and Department of Biology and Biochemistry, University of Bath, Claverton Down, Bath, BA2 7AY, UK
| | - Nicholas K Priest
- Milner Centre for Evolution and Department of Biology and Biochemistry, University of Bath, Claverton Down, Bath, BA2 7AY, UK
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42
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Pigeault R, Nicot A, Gandon S, Rivero A. Mosquito age and avian malaria infection. Malar J 2015; 14:383. [PMID: 26424326 PMCID: PMC4589955 DOI: 10.1186/s12936-015-0912-z] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2015] [Accepted: 09/25/2015] [Indexed: 11/10/2022] Open
Abstract
Background The immune system of many insects wanes dramatically with age, leading to the general prediction that older insects should be more susceptible to infection than their younger counterparts. This prediction is however challenged by numerous studies showing that older insects are more resistant to a range of pathogens. The effect of age on susceptibility to infections is particularly relevant for mosquitoes given their role as vectors of malaria and other diseases. Despite this, the effect of mosquito age on Plasmodium susceptibility has been rarely explored, either experimentally or theoretically. Methods Experiments were carried out using the avian malaria parasite Plasmodium relictum and its natural vector in the field, the mosquito Culex pipiens. Both innate immune responses (number and type of circulating haemocytes) and Plasmodium susceptibility (prevalence and burden) were quantified in seven- and 17-day old females. Whether immunity or Plasmodium susceptibility are modulated by the previous blood feeding history of the mosquito was also investigated. To ensure repeatability, two different experimental blocks were carried out several weeks apart. Results Haemocyte numbers decrease drastically as the mosquitoes age. Despite this, older mosquitoes are significantly more resistant to a Plasmodium infection than their younger counterparts. Crucially, however, the age effect is entirely reversed when old mosquitoes have taken one previous non-infected blood meal. Conclusions The results agree with previous studies showing that older insects are often more resistant to infections than younger ones. These results suggest that structural and functional alterations in mosquito physiology with age may be more important than immunity in determining the probability of a Plasmodium infection in old mosquitoes. Possible explanations for why the effect is reversed in blood-fed mosquitoes are discussed. The reversal of the age effect in blood fed mosquitoes implies that age is unlikely to have a significant impact on mosquito susceptibility in the field. Electronic supplementary material The online version of this article (doi:10.1186/s12936-015-0912-z) contains supplementary material, which is available to authorized users.
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Affiliation(s)
| | - Antoine Nicot
- MIVEGEC, UMR CNRS, 5290, Montpellier, France. .,CEFE, UMR CNRS, 5175, Montpellier, France.
| | | | - Ana Rivero
- MIVEGEC, UMR CNRS, 5290, Montpellier, France.
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43
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Heinig RL, Paaijmans KP, Hancock PA, Thomas MB. The potential for fungal biopesticides to reduce malaria transmission under diverse environmental conditions. J Appl Ecol 2015; 52:1558-1566. [PMID: 26792946 PMCID: PMC4716011 DOI: 10.1111/1365-2664.12522] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The effectiveness of conventional malaria vector control is being threatened by the spread of insecticide resistance. One promising alternative to chemicals is the use of naturally-occurring insect-killing fungi. Numerous laboratory studies have shown that isolates of fungal pathogens such as Beauveria bassiana can infect and kill adult mosquitoes, including those resistant to chemical insecticides.Unlike chemical insecticides, fungi may take up to a week or more to kill mosquitoes following exposure. This slow kill speed can still reduce malaria transmission because the malaria parasite itself takes at least eight days to complete its development within the mosquito. However, both fungal virulence and parasite development rate are strongly temperature-dependent, so it is possible that biopesticide efficacy could vary across different transmission environments.We examined the virulence of a candidate fungal isolate against two key malaria vectors at temperatures from 10-34 °C. Regardless of temperature, the fungus killed more than 90% of exposed mosquitoes within the predicted duration of the malarial extrinsic incubation period, a result that was robust to realistic diurnal temperature variation.We then incorporated temperature sensitivities of a suite of mosquito, parasite and fungus life-history traits that are important determinants of malaria transmission into a stage-structured malaria transmission model. The model predicted that, at achievable daily fungal infection rates, fungal biopesticides have the potential to deliver substantial reductions in the density of malaria-infectious mosquitoes across all temperatures representative of malaria transmission environments.Synthesis and applications. Our study combines empirical data and theoretical modelling to prospectively evaluate the potential of fungal biopesticides to control adult malaria vectors. Our results suggest that Beauveria bassiana could be a potent tool for malaria control and support further development of fungal biopesticides to manage infectious disease vectors.
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Affiliation(s)
- R L Heinig
- Center for Infectious Disease Dynamics and Department of Entomology, The Pennsylvania State University, University Park, PA, USA
| | - Krijn P Paaijmans
- ISGlobal, Barcelona Centre for International Health Research (CRESIB), Hospital Clínic-Universitat de Barcelona, Barcelona, Spain
| | | | - Matthew B Thomas
- Center for Infectious Disease Dynamics and Department of Entomology, The Pennsylvania State University, University Park, PA, USA
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44
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The potential for fungal biopesticides to reduce malaria transmission under diverse environmental conditions. Curr Nutr Rep 2015. [PMID: 26792946 DOI: 10.1007/s13668-012-0032-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The effectiveness of conventional malaria vector control is being threatened by the spread of insecticide resistance. One promising alternative to chemicals is the use of naturally-occurring insect-killing fungi. Numerous laboratory studies have shown that isolates of fungal pathogens such as Beauveria bassiana can infect and kill adult mosquitoes, including those resistant to chemical insecticides.Unlike chemical insecticides, fungi may take up to a week or more to kill mosquitoes following exposure. This slow kill speed can still reduce malaria transmission because the malaria parasite itself takes at least eight days to complete its development within the mosquito. However, both fungal virulence and parasite development rate are strongly temperature-dependent, so it is possible that biopesticide efficacy could vary across different transmission environments.We examined the virulence of a candidate fungal isolate against two key malaria vectors at temperatures from 10-34 °C. Regardless of temperature, the fungus killed more than 90% of exposed mosquitoes within the predicted duration of the malarial extrinsic incubation period, a result that was robust to realistic diurnal temperature variation.We then incorporated temperature sensitivities of a suite of mosquito, parasite and fungus life-history traits that are important determinants of malaria transmission into a stage-structured malaria transmission model. The model predicted that, at achievable daily fungal infection rates, fungal biopesticides have the potential to deliver substantial reductions in the density of malaria-infectious mosquitoes across all temperatures representative of malaria transmission environments.Synthesis and applications. Our study combines empirical data and theoretical modelling to prospectively evaluate the potential of fungal biopesticides to control adult malaria vectors. Our results suggest that Beauveria bassiana could be a potent tool for malaria control and support further development of fungal biopesticides to manage infectious disease vectors.
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45
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Reiskind MH, Janairo MS. Late-instar Behavior of Aedes aegypti (Diptera: Culicidae) Larvae in Different Thermal and Nutritive Environments. JOURNAL OF MEDICAL ENTOMOLOGY 2015; 52:789-796. [PMID: 26336228 DOI: 10.1093/jme/tjv088] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/22/2015] [Accepted: 06/08/2015] [Indexed: 06/05/2023]
Abstract
The effects of temperature on ectotherm growth have been well documented. How temperature affects foraging behavior is less well explored, and has not been studied in larval mosquitoes. We hypothesized that temperature changes foraging behavior in the aquatic larval phase of the mosquito, Aedes aegypti L. Based on empirical results in other systems, we predicted that foraging effort would increase at higher temperatures in these insects. We tested this prediction over three temperature conditions at two food levels. We measured behaviors by video recording replicated cohorts of fourth-instar mosquitoes and assessing individual behavior and time budgets using an ethogram. We found both food level and temperature had significant impacts on larval foraging behavior, with more time spent actively foraging at low food levels and at low temperatures, and more occurrences of active foraging at both temperature extremes. These results are contrary to some of our predictions, but fit into theoretical responses to temperature based upon dynamic energy budget models.
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Affiliation(s)
- Michael H Reiskind
- Department of Entomology, North Carolina State University, Raleigh, NC 27695.
| | - M Shawn Janairo
- Department of Entomology, North Carolina State University, Raleigh, NC 27695
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46
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Westby KM, Juliano SA. Simulated Seasonal Photoperiods and Fluctuating Temperatures Have Limited Effects on Blood Feeding and Life History in Aedes triseriatus (Diptera: Culicidae). JOURNAL OF MEDICAL ENTOMOLOGY 2015; 52:896-906. [PMID: 26336255 PMCID: PMC4643637 DOI: 10.1093/jme/tjv116] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/10/2015] [Accepted: 07/16/2015] [Indexed: 06/05/2023]
Abstract
Biotic and abiotic factors change seasonally and impact life history in temperate-zone ectotherms. Temperature and photoperiod are factors that change in predictable ways. Most studies testing for effects of temperature on vectors use constant temperatures and ignore potential correlated effects of photoperiod. In two experiments, we tested for effects of larval rearing environments creating ecologically relevant temperatures and photoperiods simulating early and late season conditions (June and August), or constant temperatures (cool and warm) with the June or August photoperiods, respectively. We determined effects on survivorship, development, size, and a composite performance index in a temperate-zone population of Aedes triseriatus (Say). We followed cohorts of resulting females, all held under the same environmental conditions, to assess carry-over effects of rearing conditions for larvae on longevity, blood feeding, and egg production. Larval survivorship was affected by treatment in one experiment. Development time was greater in the June and cool treatments, but the constant and fluctuating temperatures did not differ. Significantly larger mosquitoes were produced in fluctuating versus constant temperature treatments. There were no significant treatment effects on the composite performance index. Adult female longevity was lower after rearing at constant versus fluctuating temperature, but there was no difference between June and August, nor did size affect longevity. There was no effect of treatments on blood feeding and a limited effect on egg production. We conclude that seasonal temperatures and photoperiods during development have limited effects on this population of A. triseriatus and find little evidence of strong effects of fluctuating versus constant temperatures.
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Affiliation(s)
- K M Westby
- School of Biological Sciences, Illinois State University, Normal, IL 61790-4120. Present address: Washington University in St Louis, Tyson Research Center, 6750 Tyson Valley Road, Eureka, MO 63025.
| | - S A Juliano
- School of Biological Sciences, Illinois State University, Normal, IL 61790-4120.
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Gervasi SS, Civitello DJ, Kilvitis HJ, Martin LB. The context of host competence: a role for plasticity in host-parasite dynamics. Trends Parasitol 2015; 31:419-25. [PMID: 26048486 PMCID: PMC4567474 DOI: 10.1016/j.pt.2015.05.002] [Citation(s) in RCA: 76] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2015] [Revised: 04/15/2015] [Accepted: 05/05/2015] [Indexed: 12/17/2022]
Abstract
Even apparently similar hosts can respond differently to the same parasites. Some individuals or specific groups of individuals disproportionately affect disease dynamics. Understanding the sources of among-host heterogeneity in the ability to transmit parasites would improve disease management. A major source of host variation might be phenotypic plasticity - the tendency for phenotypes to change across different environments. Plasticity might be as important as, or even more important than, genetic change, especially in light of human modifications of the environment, because it can occur on a more rapid timescale than evolution. We argue that variation in phenotypic plasticity among and within species strongly contributes to epidemiological dynamics when parasites are shared among multiple hosts, which is often the case.
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Affiliation(s)
- Stephanie S Gervasi
- Department of Integrative Biology, University of South Florida, Science Center 110, Tampa, FL 33620, USA.
| | - David J Civitello
- Department of Integrative Biology, University of South Florida, Science Center 110, Tampa, FL 33620, USA
| | - Holly J Kilvitis
- Department of Integrative Biology, University of South Florida, Science Center 110, Tampa, FL 33620, USA
| | - Lynn B Martin
- Department of Integrative Biology, University of South Florida, Science Center 110, Tampa, FL 33620, USA
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48
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Kaunisto S, Ylonen H, Kortet R. Passive sinking into the snow as possible survival strategy during the off-host stage in an insect ectoparasite. Folia Parasitol (Praha) 2015; 62. [DOI: 10.14411/fp.2015.038] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2015] [Accepted: 04/22/2015] [Indexed: 11/19/2022]
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49
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Cator LJ, Pietri JE, Murdock CC, Ohm JR, Lewis EE, Read AF, Luckhart S, Thomas MB. Immune response and insulin signalling alter mosquito feeding behaviour to enhance malaria transmission potential. Sci Rep 2015; 5:11947. [PMID: 26153094 PMCID: PMC4495552 DOI: 10.1038/srep11947] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2015] [Accepted: 06/04/2015] [Indexed: 12/18/2022] Open
Abstract
Malaria parasites alter mosquito feeding behaviour in a way that enhances parasite transmission. This is widely considered a prime example of manipulation of host behaviour to increase onward transmission, but transient immune challenge in the absence of parasites can induce the same behavioural phenotype. Here, we show that alterations in feeding behaviour depend on the timing and dose of immune challenge relative to blood ingestion and that these changes are functionally linked to changes in insulin signalling in the mosquito gut. These results suggest that altered phenotypes derive from insulin signalling-dependent host resource allocation among immunity, blood feeding, and reproduction in a manner that is not specific to malaria parasite infection. We measured large increases in mosquito survival and subsequent transmission potential when feeding patterns are altered. Leveraging these changes in physiology, behaviour and life history could promote effective and sustainable control of female mosquitoes responsible for transmission.
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Affiliation(s)
- Lauren J Cator
- Grand Challenges in Ecosystem and Environment, Department of Life Sciences, Imperial College London, Silwood Park
| | - Jose E Pietri
- Department of Medical Microbiology and Immunology, University of California, Davis
| | - Courtney C Murdock
- Department of Infectious Disease in College of Veterinary Medicine and Odum School of Ecology, University of Georgia
| | - Johanna R Ohm
- Center for Infectious Disease Dynamics, Pennsylvania State University
| | - Edwin E Lewis
- Department of Entomology, University of California, Davis
| | - Andrew F Read
- Center for Infectious Disease Dynamics, Pennsylvania State University
| | - Shirley Luckhart
- Department of Medical Microbiology and Immunology, University of California, Davis
| | - Matthew B Thomas
- Center for Infectious Disease Dynamics, Pennsylvania State University
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LaDeau SL, Allan BF, Leisnham PT, Levy MZ. The ecological foundations of transmission potential and vector-borne disease in urban landscapes. Funct Ecol 2015; 29:889-901. [PMID: 26549921 PMCID: PMC4631442 DOI: 10.1111/1365-2435.12487] [Citation(s) in RCA: 120] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Urban transmission of arthropod-vectored disease has increased in recent decades. Understanding and managing transmission potential in urban landscapes requires integration of sociological and ecological processes that regulate vector population dynamics, feeding behavior, and vector-pathogen interactions in these unique ecosystems. Vectorial capacity is a key metric for generating predictive understanding about transmission potential in systems with obligate vector transmission. This review evaluates how urban conditions, specifically habitat suitability and local temperature regimes, and the heterogeneity of urban landscapes can influence the biologically-relevant parameters that define vectorial capacity: vector density, survivorship, biting rate, extrinsic incubation period, and vector competence.Urban landscapes represent unique mosaics of habitat. Incidence of vector-borne disease in urban host populations is rarely, if ever, evenly distributed across an urban area. The persistence and quality of vector habitat can vary significantly across socio-economic boundaries to influence vector species composition and abundance, often generating socio-economically distinct gradients of transmission potential across neighborhoods.Urban regions often experience unique temperature regimes, broadly termed urban heat islands (UHI). Arthropod vectors are ectothermic organisms and their growth, survival, and behavior are highly sensitive to environmental temperatures. Vector response to UHI conditions is dependent on regional temperature profiles relative to the vector's thermal performance range. In temperate climates UHI can facilitate increased vector development rates while having countervailing influence on survival and feeding behavior. Understanding how urban heat island (UHI) conditions alter thermal and moisture constraints across the vector life cycle to influence transmission processes is an important direction for both empirical and modeling research.There remain persistent gaps in understanding of vital rates and drivers in mosquito-vectored disease systems, and vast holes in understanding for other arthropod vectored diseases. Empirical studies are needed to better understand the physiological constraints and socio-ecological processes that generate heterogeneity in critical transmission parameters, including vector survival and fitness. Likewise, laboratory experiments and transmission models must evaluate vector response to realistic field conditions, including variability in sociological and environmental conditions.
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Affiliation(s)
| | - Brian F. Allan
- Department of Entomology, University of Illinois, Urbana, IL, USA
| | - Paul T. Leisnham
- Concentration in Ecosystem Health and Natural Resource Management, Department of Environmental Science & Technology, University of Maryland, College Park, MD, USA
| | - Michael Z. Levy
- Department of Biostatistics & Epidemiology, University of Pennsylvania, Philadelphia, PA, USA
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