The effect of extreme environmental temperature spikes on mosquito longevity, fertility and ability to transmit viruses
Lead Research Organisation:
University of Liverpool
Department Name: Evolution, Ecology and Behaviour
Abstract
Background and novelty
Longevity, fertility and vector competence are central factors in the geographic range of mosquitoes and the epidemiology of the viruses they transmit. Typically, these traits are studied either in highly controlled laboratory conditions, or observed more loosely in field settings without experimentation.
In Drosophila, males are often sterilised by temperatures several degrees lower than their lethal limit, resulting in environment-induced restriction of their geographic range. Conversely, in Culicoides biting midges, heatwaves increase competence for viruses.
If present in mosquitoes, these would have contrasting effects on the ranges of vector and virus.
Objectives
In this project, the student will combine field collection and laboratory experimentation to understand the effect of natural heat waves on two native UK species: Culex pipiens pipiens, and Ochlerotatus detritus.
1) In the lab, the student will administer UK-heatwave representative thermal-shocks to colony Culex mosquitoes and assess the effects on mortality and fertility, to enable estimation of thermal tolerance.
2) Using these results, sub-lethal (heatwave representative) temperatures will be administered to colony mosquitoes. Mosquitoes will then be challenged with Usutu virus, to investigate environmentally induced vector competence.
3) Wild Culex pipiens pipiens, and Ochlerotatus detritus immatures will be collected from field sites after heatwaves. Resultant adults will be assessed for fertility, mortality and challenged with Usutu virus.
4) During experimental downtime, the student will be trained in climate modelling and use their experimental results to model the thermal range, geographic limitations, and virus transmission of these two species in the UK, both now and under future climate scenarios.
Timeliness
As a direct consequence of climate change, the habitable range for mosquitoes is currently changing rapidly. Mosquitoes are disappearing from some tropical regions where temperatures are increasing and rainfall reducing. Conversely, temperature mosquitoes are spreading polewards, bringing with them important animal and human viruses. The different environmental conditions they face will determine their new geographic ranges.
As a result of climate change, there has been extensive and uneven changes in global temperature, heatwave, humidity, and precipitation patterns leading to the general movement of mosquitoes and their viruses, poleward, away from some tropical regions where temperature is too high and rainfall too low toward more temperate climates. For example, in recent years, there has been a spread of zoonotic viruses such as Usutu virus (USUV) throughout mainland Europe, with its detection in the UK occurring in 2020.
Previous studies in different insects have shown contrasting effects of heatwaves, e.g., biting midges showing increased transmission of viruses in comparison to male fruit flies that become sterile several degrees below their lethal limit. Similar effects in mosquitoes could have implications on the geographic ranges of vectors, viruses, and who and where is at risk.
The aim of this study is to determine which relevant temperature-dependent traits, such as longevity, fertility, and vector competence, are affected by spikes in environmental temperature (heatwaves). I will use the native UK vector species Culex pipiens and Ochlerotatus detritus, both in colony and wild-caught individuals.
By administering UK-heatwave representative thermal shocks to colony Culex mosquitoes, temperature effects on mortality and fertility will be determined to estimate thermal tolerance and understand the effect of natural heatwaves. Following the identification of survivable sub-lethal temperatures, mosquitoes will then be challenged with USUV to assess vector competence possibilities induced by the environment. These findings will then be combined with field collected Culex and
Longevity, fertility and vector competence are central factors in the geographic range of mosquitoes and the epidemiology of the viruses they transmit. Typically, these traits are studied either in highly controlled laboratory conditions, or observed more loosely in field settings without experimentation.
In Drosophila, males are often sterilised by temperatures several degrees lower than their lethal limit, resulting in environment-induced restriction of their geographic range. Conversely, in Culicoides biting midges, heatwaves increase competence for viruses.
If present in mosquitoes, these would have contrasting effects on the ranges of vector and virus.
Objectives
In this project, the student will combine field collection and laboratory experimentation to understand the effect of natural heat waves on two native UK species: Culex pipiens pipiens, and Ochlerotatus detritus.
1) In the lab, the student will administer UK-heatwave representative thermal-shocks to colony Culex mosquitoes and assess the effects on mortality and fertility, to enable estimation of thermal tolerance.
2) Using these results, sub-lethal (heatwave representative) temperatures will be administered to colony mosquitoes. Mosquitoes will then be challenged with Usutu virus, to investigate environmentally induced vector competence.
3) Wild Culex pipiens pipiens, and Ochlerotatus detritus immatures will be collected from field sites after heatwaves. Resultant adults will be assessed for fertility, mortality and challenged with Usutu virus.
4) During experimental downtime, the student will be trained in climate modelling and use their experimental results to model the thermal range, geographic limitations, and virus transmission of these two species in the UK, both now and under future climate scenarios.
Timeliness
As a direct consequence of climate change, the habitable range for mosquitoes is currently changing rapidly. Mosquitoes are disappearing from some tropical regions where temperatures are increasing and rainfall reducing. Conversely, temperature mosquitoes are spreading polewards, bringing with them important animal and human viruses. The different environmental conditions they face will determine their new geographic ranges.
As a result of climate change, there has been extensive and uneven changes in global temperature, heatwave, humidity, and precipitation patterns leading to the general movement of mosquitoes and their viruses, poleward, away from some tropical regions where temperature is too high and rainfall too low toward more temperate climates. For example, in recent years, there has been a spread of zoonotic viruses such as Usutu virus (USUV) throughout mainland Europe, with its detection in the UK occurring in 2020.
Previous studies in different insects have shown contrasting effects of heatwaves, e.g., biting midges showing increased transmission of viruses in comparison to male fruit flies that become sterile several degrees below their lethal limit. Similar effects in mosquitoes could have implications on the geographic ranges of vectors, viruses, and who and where is at risk.
The aim of this study is to determine which relevant temperature-dependent traits, such as longevity, fertility, and vector competence, are affected by spikes in environmental temperature (heatwaves). I will use the native UK vector species Culex pipiens and Ochlerotatus detritus, both in colony and wild-caught individuals.
By administering UK-heatwave representative thermal shocks to colony Culex mosquitoes, temperature effects on mortality and fertility will be determined to estimate thermal tolerance and understand the effect of natural heatwaves. Following the identification of survivable sub-lethal temperatures, mosquitoes will then be challenged with USUV to assess vector competence possibilities induced by the environment. These findings will then be combined with field collected Culex and
Organisations
Studentship Projects
| Project Reference | Relationship | Related To | Start | End | Student Name |
|---|---|---|---|---|---|
| NE/S00713X/1 | 01/10/2019 | 30/09/2028 | |||
| 2888071 | Studentship | NE/S00713X/1 | 01/10/2023 | 31/03/2027 | Lorna Glenn |