Some like it hot: exploring the interplay between host and parasite responses to temperature

Project background

Review news reports from the past few years and two topics will consistently repeat, the threats posed by climate change and emerging infectious diseases (e.g. Covid-19, H1N1, Zika). These two disparate threats are not independent, as climate may directly affect parasites as well as hosts. Understanding how hosts, parasites and climate interact is therefore essential to our understanding of the consequences of climate change. Ectotherms are particularly susceptible to climate change due to their limited ability to control their internal temperature. Some social insects, however, have demonstrated behavioural traits that help to protect their colonies against temperature fluctuations (e.g. wing fanning - bees, nest restructuring - ants)1,2. Pathogens can also alter the structure of social insect colonies3 and it is therefore possible that parasites may change (synergistically or antagonistically) the way social insects manage heat stressors. 

Different organisms (including parasites) display different thermal performance curves2, these are physiological responses to temperature. In social insects these underlying physiological traits will interact with the behavioural traits used to mitigate against heat stress. Understanding how these basic biological processes scale up from individuals to populations is a challenge. This PhD will explore the individual to population level effects of temperature and pathogens using two model hosts, the ant species Lasius niger and Formica rufa (displaying markedly different thermal performance curves) along with two naturally occurring generalist pathogens, the directly transmitted Acute Bee Paralysis Virus and the environmentally transmitted Steinernema feltiae.  

Project aims and methods

Aims

To explore the individual to population level consequences for social insects of the dual threats of rising temperatures and emerging infections. Specifically, we will determine how different thermal performance curves affect: i) individual ant foraging behaviour; ii) colony-level behaviour and structure; iii) individual capacity to withstand infection and iv) colony level capacity to withstand infection. Simultaneously, we will determine how rising temperature affects initial disease emergence and onward transmission of directly and indirectly (environmentally) transmitted pathogens. 

Methods 

These aims will be addressed through a combination of experimental and modelling approaches. First, heat stress and infection experiments on individual ants and small experimental colonies collected from the field will be used to reveal how different species respond to the joint stressors of thermal change and infectious disease. Second, in-silico agent-based modelling will draw on these experimental data to predict the effect of environmental temperature variation and infection on whole colony activity patterns and fitness. Finally, we will explore these concepts at large biogeographic scales by drawing on global estimates of thermal microclimates and applying mechanistic distribution models.  

Candidate requirements 

Candidates do not require any specific skillset but a background in behavioural ecology, entomology and/or parasitology would be an advantage. Statistical and mathematical modelling skills, while also advantageous, are not a pre-requisite as training will be given during the PhD, and evidence of a capacity for critical and logical thinking is of greater value.  

Project partners  

At Cardiff, the project will be supervised by Dr Jo Lello and Dr Tom Bishop. Jo Lello has expertise in emerging infectious diseases and agent-based modelling while Tom Bishop focuses on the thermal ecology of ants. Dr Paul Eggleton, an expert in social insect ecology, will co-supervise and provide access to Natural History Museum ant collections and equipment to gain additional morphological and parasitological data on the ant species studied. Dr Regan Early at the University of Exeter is an expert in global change ecology and species distribution modelling – her skills will be critical to the upscaling of the experimental findings to continental and global scales.  

Training 

Training will be multi-disciplinary involving fieldworks skills (ant collection), lab skills (maintenance of ant colonies and pathogen cultures, thermotolerance experiments, infection assays, behavioural assays), and mathematical (statistical and agent-based modelling). Students without prior modelling experience will sit in on relevant aspects of the final year UG Systems Biology module and the new MSc in Big Data as well as receiving support from the supervisory team.  

How to apply

Details about how to apply for this project can be found here. We suggest you also read our helpful document about applying for a PhD.

Find out more about the GW4 Doctorial Training programme.