scholarly journals The effect of resource limitation on the temperature-dependence of mosquito population fitness

2020 ◽  
Author(s):  
Paul J. Huxley ◽  
Kris A. Murray ◽  
Samraat Pawar ◽  
Lauren J. Cator
Keyword(s):  
Disease Transmission ◽  
Development Time ◽  
Natural Populations ◽  
Resource Limitation ◽  
Population Level ◽  
Adult Size ◽  
Population Modelling ◽  
Juvenile Mortality ◽  
Low Resource ◽  
High Resource

ABSTRACTLaboratory-derived temperature dependencies of life history traits are increasingly being used to make mechanistic predictions for how climatic warming will affect vector-borne disease dynamics, partially by affecting abundance dynamics of the vector population. These temperature-trait relationships are typically estimated from populations reared on optimal resource supply, even though natural populations of vectors are expected to experience variation in resource supply, including intermittent resource limitation. Using laboratory experiments on the mosquito Aedes aegypti, a principal arbovirus vector, combined with stage-structured population modelling, we show that low-resource supply significantly depresses the vector’s maximal population growth rate across the entire temperature range (22-32°C) and causes it to peak at a lower temperature than at high-resource supply. This effect is primarily driven by an increase in juvenile mortality and development time, combined with an exaggerated decrease in adult size with temperature at low-resource supply. Our study suggests that projections of vector abundance and disease transmission based on laboratory studies are likely to substantially underestimate how resource supply can modulate the temperature-dependency of population-level fitness through its influence on juvenile survival and development time. Our results provide compelling evidence for future studies to consider resource supply when predicting the effects of climate and habitat change on disease vectors and transmission.

scholarly journals The effect of resource limitation on the temperature dependence of mosquito population fitness

2021 ◽  
Vol 288 (1949) ◽  
Author(s):  
Paul J. Huxley ◽  
Kris A. Murray ◽  
Samraat Pawar ◽  
Lauren J. Cator
Keyword(s):  
Disease Transmission ◽  
Resource Limitation ◽  
Adult Size ◽  
Population Modelling ◽  
Juvenile Mortality ◽  
Low Resource ◽  
Vector Borne Disease ◽  
High Resource ◽  
Optimal Resource ◽  
Vector Borne

Laboratory-derived temperature dependencies of life-history traits are increasingly being used to make mechanistic predictions for how climatic warming will affect vector-borne disease dynamics, partially by affecting abundance dynamics of the vector population. These temperature–trait relationships are typically estimated from juvenile populations reared on optimal resource supply, even though natural populations of vectors are expected to experience variation in resource supply, including intermittent resource limitation. Using laboratory experiments on the mosquito Aedes aegypti , a principal arbovirus vector, combined with stage-structured population modelling, we show that low-resource supply in the juvenile life stages significantly depresses the vector's maximal population growth rate across the entire temperature range (22–32°C) and causes it to peak at a lower temperature than at high-resource supply. This effect is primarily driven by an increase in juvenile mortality and development time, combined with a decrease in adult size with temperature at low-resource supply. Our study suggests that most projections of temperature-dependent vector abundance and disease transmission are likely to be biased because they are based on traits measured under optimal resource supply. Our results provide compelling evidence for future studies to consider resource supply when predicting the effects of climate and habitat change on vector-borne disease transmission, disease vectors and other arthropods.

scholarly journals A framework for designing medical devices resilient to low-resource settings

2021 ◽  
Vol 17 (1) ◽  
Author(s):  
Davide Piaggio ◽  
Rossana Castaldo ◽  
Marco Cinelli ◽  
Sara Cinelli ◽  
Alessia Maccaro ◽  
...  
Keyword(s):  
Delphi Study ◽  
Middle Income ◽  
Low Resource Settings ◽  
Health Technologies ◽  
Low Resource ◽  
Middle Income Countries ◽  
High Resource ◽  
International Experts ◽  
Global Population ◽  
Different Parts

Abstract Background To date (April 2021), medical device (MD) design approaches have failed to consider the contexts where MDs can be operationalised. Although most of the global population lives and is treated in Low- and Middle-Income Countries (LMCIs), over 80% of the MD market share is in high-resource settings, which set de facto standards that cannot be taken for granted in lower resource settings. Using a MD designed for high-resource settings in LMICs may hinder its safe and efficient operationalisation. In the literature, many criteria for frameworks to support resilient MD design were presented. However, since the available criteria (as of 2021) are far from being consensual and comprehensive, the aim of this study is to raise awareness about such challenges and to scope experts’ consensus regarding the essentiality of MD design criteria. Results This paper presents a novel application of Delphi study and Multiple Criteria Decision Analysis (MCDA) to develop a framework comprising 26 essential criteria, which were evaluated and chosen by international experts coming from different parts of the world. This framework was validated by analysing some MDs presented in the WHO Compendium of innovative health technologies for low-resource settings. Conclusions This novel holistic framework takes into account some domains that are usually underestimated by MDs designers. For this reason, it can be used by experts designing MDs resilient to low-resource settings and it can also assist policymakers and non-governmental organisations in shaping the future of global healthcare.

NOTE ON THE UNIQUENESS OF AN ENDEMIC EQUILIBRIUM OF AN EPIDEMIC MODEL WITH BOOSTING OF IMMUNITY

2021 ◽  
pp. 1-12
Author(s):  
LIU YANG ◽  
YUKIHIKO NAKATA
Keyword(s):  
Epidemic Model ◽  
Disease Transmission ◽  
Immune Status ◽  
Natural Infection ◽  
Population Level ◽  
Qualitative Property ◽  
Endemic Equilibrium ◽  
Unique Existence ◽  
Nonlinear Version ◽  
Age Dependent

For some diseases, it is recognized that immunity acquired by natural infection and vaccination subsequently wanes. As such, immunity provides temporal protection to recovered individuals from an infection. An immune period is extended owing to boosting of immunity by asymptomatic re-exposure to an infection. An individual’s immune status plays an important role in the spread of infectious diseases at the population level. We study an age-dependent epidemic model formulated as a nonlinear version of the Aron epidemic model, which incorporates boosting of immunity by a system of delay equations and study the existence of an endemic equilibrium to observe whether boosting of immunity changes the qualitative property of the existence of the equilibrium. We establish a sufficient condition related to the strength of disease transmission from subclinical and clinical infective populations, for the unique existence of an endemic equilibrium.

Low Resource ASR: The Surprising Effectiveness of High Resource Transliteration

2021 ◽  
Author(s):  
Shreya Khare ◽  
Ashish Mittal ◽  
Anuj Diwan ◽  
Sunita Sarawagi ◽  
Preethi Jyothi ◽  
...  
Keyword(s):  
Low Resource ◽  
High Resource

scholarly journals Contrasting Patterns of Virus Protection and Functional Incompatibility Genes in Two ConspecificWolbachiaStrains fromDrosophila pandora

2018 ◽  
Vol 85 (5) ◽  
Author(s):  
Angelique K. Asselin ◽  
Simon Villegas-Ospina ◽  
Ary A. Hoffmann ◽  
Jeremy C. Brownlie ◽  
Karyn N. Johnson
Keyword(s):  
Disease Transmission ◽  
Cytoplasmic Incompatibility ◽  
Natural Populations ◽  
Differential Protection ◽  
Content Type ◽  
Infection Dynamics ◽  
Modification Factor ◽  
Control Disease ◽  
Multiple Strains ◽  
High Degree

ABSTRACTWolbachiainfections can present different phenotypes in hosts, including different forms of reproductive manipulation and antiviral protection, which may influence infection dynamics within host populations. In populations ofDrosophila pandoratwo distinctWolbachiastrains coexist, each manipulating host reproduction: strainwPanCI causes cytoplasmic incompatibility (CI), whereas strainwPanMK causes male killing (MK). CI occurs when aWolbachia-infected male mates with a female not infected with a compatible type ofWolbachia, leading to nonviable offspring.wPanMK can rescuewPanCI-induced CI but is unable to induce CI. The antiviral protection phenotypes provided by thewPanCI andwPanMK infections were characterized; the strains showed differential protection phenotypes, whereby cricket paralysis virus (CrPV)-induced mortality was delayed in flies infected withwPanMK but enhanced in flies infected withwPanCI compared to their respectiveWolbachia-cured counterparts. Homologs of thecifAandcifBgenes involved in CI identified inwPanMK andwPanCI showed a high degree of conservation; however, the CifB protein inwPanMK is truncated and is likely nonfunctional. The presence of a likely functional CifA inwPanMK andwPanMK’s ability to rescuewPanCI-induced CI are consistent with the recent confirmation of CifA’s involvement in CI rescue, and the absence of a functional CifB protein further supports its involvement as a CI modification factor. Taken together, these findings indicate thatwPanCI andwPanMK have different relationships with their hosts in terms of their protective and CI phenotypes. It is therefore likely that different factors influence the prevalence and dynamics of these coinfections in naturalDrosophila pandorahosts.IMPORTANCEWolbachiastrains are common endosymbionts in insects, with multiple strains often coexisting in the same species. The coexistence of multiple strains is poorly understood but may rely onWolbachiaorganisms having diverse phenotypic effects on their hosts. AsWolbachiais increasingly being developed as a tool to control disease transmission and suppress pest populations, it is important to understand the ways in which multipleWolbachiastrains persist in natural populations and how these might then be manipulated. We have therefore investigated viral protection and the molecular basis of cytoplasmic incompatibility in two coexistingWolbachiastrains with contrasting effects on host reproduction.

scholarly journals Perspectives from animal demography on incorporating evolutionary mechanism into plant population dynamics

2018 ◽  
Author(s):  
Maria Paniw
Keyword(s):  
Environmental Change ◽  
Evolutionary Dynamics ◽  
Natural Populations ◽  
Population Level ◽  
Plant Population ◽  
Future Research ◽  
Phenotypic Traits ◽  
Plant Population Dynamics ◽  
Future Research Agenda ◽  
Powerful Approach

AbstractWith a growing number of long-term, individual-based data on natural populations available, it has become increasingly evident that environmental change affects populations through complex, simultaneously occurring demographic and evolutionary processes. Analyses of population-level responses to environmental change must therefore integrate demography and evolution into one coherent framework. Integral projection models (IPMs), which can relate genetic and phenotypic traits to demographic and population-level processes, offer a powerful approach for such integration. However, a rather artificial divide exists in how plant and animal population ecologists use IPMs. Here, I argue for the integration of the two sub-disciplines, particularly focusing on how plant ecologists can diversify their toolset to investigate selection pressures and eco-evolutionary dynamics in plant population models. I provide an overview of approaches that have applied IPMs for eco-evolutionary studies and discuss a potential future research agenda for plant population ecologists. Given an impending extinction crisis, a holistic look at the interacting processes mediating population persistence under environmental change is urgently needed.

scholarly journals Vaccinating Adolescents and Children Significantly Reduces COVID-19 Morbidity and Mortality across All Ages: A Popula-Tion-Based Modeling Study Using the UK as an Example

Vaccines ◽  
2021 ◽  
Vol 9 (10) ◽  
pp. 1180
Author(s):  
Tinevimbo Shiri ◽  
Marc Evans ◽  
Carla A. Talarico ◽  
Angharad R. Morgan ◽  
Maaz Mussad ◽  
...  
Keyword(s):  
Disease Transmission ◽  
Age Groups ◽  
Population Level ◽  
Vital Role ◽  
Morbidity And Mortality ◽  
Transmission Model ◽  
Base Case ◽  
Global Public Health ◽  
The Uk ◽  
The Impact

Debate persists around the risk–benefit balance of vaccinating adolescents and children against COVID-19. Central to this debate is quantifying the contribution of adolescents and children to the transmission of SARS-CoV-2, and the potential impact of vaccinating these age groups. In this study, we present a novel SEIR mathematical disease transmission model that quantifies the impact of different vaccination strategies on population-level SARS-CoV-2 infections and clinical outcomes. The model employs both age- and time-dependent social mixing patterns to capture the impact of changes in restrictions. The model was used to assess the impact of vaccinating adolescents and children on the natural history of the COVID-19 pandemic across all age groups, using the UK as an example. The base case model demonstrates significant increases in COVID-19 disease burden in the UK following a relaxation of restrictions, if vaccines are limited to those ≥18 years and vulnerable adolescents (≥12 years). Including adolescents and children in the vaccination program could reduce overall COVID-related mortality by 57%, and reduce cases of long COVID by 75%. This study demonstrates that vaccinating adolescents and children has the potential to play a vital role in reducing SARS-CoV-2 infections, and subsequent COVID-19 morbidity and mortality, across all ages. Our results have major global public health implications and provide valuable information to inform a potential pandemic exit strategy.

scholarly journals Comparative analysis of the ftness of Drosophila virilis lines contrasting in response to stress

2019 ◽  
Vol 22 (8) ◽  
pp. 1090-1096
Author(s):  
E. K. Karpova ◽  
I. Yu. Rauschenbach ◽  
N. E. Gruntenko
Keyword(s):  
Heat Stress ◽  
Natural Populations ◽  
Population Level ◽  
Stress Reaction ◽  
Egg Laying ◽  
Drosophila Virilis ◽  
Gonadotropic Hormone ◽  
Adverse Conditions ◽  
Low Intensity ◽  
Response To Stress

One of the crucial elements contributing to the adaptation of organisms to unfavorable environmental conditions is the reaction of stress. The study of its genetic control and role in adaptation to unfavorable conditions are of special interest. The juvenile hormone (JH) acts as a gonadotropic hormone in adult insects controlling the development of the ovaries, inducing vitellogenesis and oviposition. It was shown that a decrease in JH degradation in individuals reacting to adverse conditions by stress reaction (R­individuals) causes delay in egg laying and seems to allow the population to “wait out” the unfavorable conditions, thereby contributing to the adaptation at the population level. However, monitoring natural populations of D. melanogaster for the capability of stress reaction demonstrated that they have a high percentage of individuals incapable of it (NR­individuals). The study of reproductive characteristics of R­ and NR­individuals showed that under normal conditions R­individuals have the advantage of procreating offspring. Under unfavorable conditions, if the stressor is intense enough, NR­individuals die, but if its intensity is low, then they, unlike R­individuals, continue to produce offspring. Based on these data, it was hypothesized that the balance of R­ and NR­alleles in the population ensures its adaptation under frequent stresses of low intensity. To verify the hypothesis by an experiment, the ftness characteristics (lifespan, fecundity) of the R and NR lines of D. virilis were studied under normal conditions and under regular heat stress of various frequency.

scholarly journals Ecological Immunology of mosquito-malaria interactions: Of non-natural versus natural model systems and their inferences

Parasitology ◽  
2009 ◽  
Vol 136 (14) ◽  
pp. 1935-1942 ◽  
Author(s):  
F. TRIPET
Keyword(s):  
Immune Responses ◽  
Population Biology ◽  
Experimental Studies ◽  
Natural Populations ◽  
Population Level ◽  
Model Systems ◽  
Ecological Immunology ◽  
Experimental Systems ◽  
Evolutionary Context ◽  
And Function

SUMMARYThere has been a recent shift in the literature on mosquito/Plasmodium interactions with an increasingly large number of theoretical and experimental studies focusing on their population biology and evolutionary processes. Ecological immunology of mosquito-malaria interactions – the study of the mechanisms and function of mosquito immune responses to Plasmodium in their ecological and evolutionary context – is particularly important for our understanding of malaria transmission and how to control it. Indeed, describing the processes that create and maintain variation in mosquito immune responses and parasite virulence in natural populations may be as important to this endeavor as describing the immune responses themselves. For historical reasons, Ecological Immunology still largely relies on studies based on non-natural model systems. There are many reasons why current research should favour studies conducted closer to the field and more realistic experimental systems whenever possible. As a result, a number of researchers have raised concerns over the use of artificial host-parasite associations to generate inferences about population-level processes. Here I discuss and review several lines of evidence that, I believe, best illustrate and summarize the limitations of inferences generated using non-natural model systems.

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