PhD Studentship: Cloaks and Daggers: Evolution of Egg Defences in a Global Agricultural Pest

Primary Supervisor - Prof Tracey Chapman

Strong interdisciplinary training, within the ARIES Ecology and Biodiversity theme, to equip you with high-in-demand analytical skills in phenotypic and molecular genetic engineering.

Scientific Background

In all species that lay eggs externally - in nests, ponds, mudpiles, food or other substrates - eggs and young may face unpredictable exposure to harmful or beneficial microbes. Mothers may manipulate the immediate microbial environment by provisioning eggs with protective antimicrobial compounds. One enigmatic example - the focus here - occurs in a global agricultural pest, the medfly (Ceratitis capitata). Medfly mothers ‘cloak’ their eggs with potent, broad-spectrum antimicrobial peptides comprising four 'Ceratotoxins' encoded by 7 genes. These kill microbes by punching holes in them. Offspring from eggs lacking protective antimicrobials are slower to develop, giving the first insight into potential benefits and providing a springboard for you to use phenotype engineering, sequencing and gene-editing tools to determine:  

(i) Overall fitness benefits of Ceratotoxin egg cloaks under natural conditions 

(ii) Functional significance of Ceratotoxin redundancy  

(iii) Potential of Ceratotoxins for insect control 

Methodology 

(i) Fitness benefits 

Test major hypotheses for protective egg cloaks: 

• Protecting eggs and larvae from harmful microbes 
• Protecting the female reproductive tract from sexually transmitted infections 
• Creating a beneficial microbial community for larvae and eggs 
• Facilitating vertical transmission of beneficial microbes  

Assays of key fitness measures (survival, fertility, semi-natural conditions) using phenotypic manipulations (egg cloak removal, microbial add-backs), sequencing (16S rDNA of microbial communities) and molecular genetics (CRISPR-Cas9 knock-outs of Ceratotoxin gene combinations). 

(ii) Functional redundancy 

To determine if Ceratotoxin redundancy is adaptive: (i) test antimicrobial spectrum and potency of synthetic Ceratotoxin peptide mixtures, (ii) assay key fitness measures of gene-edited medflies lacking Ceratotoxins. 

(iii) Insect control 

Depending upon interests, explore (via experimentation, modelling, or quantitative literature synthesis) different possibilities for Ceratotoxin use in insect control, including engineering solutions to reduce host fitness, or to improve the health of mass-reared strains for sterile release. 

Training 

High-in-demand technical (bioinformatics, molecular genetics, microbiology, phenotype engineering) and transferrable (critical thinking, ethics, Open Research) skills. Embedded in thriving, respectful and inclusive research environment.  

Person Specification

Suiting an individual interested in tackling fundamentally important questions with applied potential for control of insects that threaten food security. 

Entry Requirements

At least UK equivalence Bachelors (Honours) 2:1. English Language requirement (Faculty of Science equivalent: IELTS 6.5 overall, 6 in each category). 

Acceptable first degree: Biological Sciences, Genetics, Ecology. 

Mode of Study: Full or part time

Start Date: 1 October 2026

Additional Funding Information 

ARIES studentships are subject to UKRI terms and conditions. Successful candidates who meet UKRI’s eligibility criteria will be awarded a fully-funded studentship, which covers fees, maintenance stipend (£20,780 p.a. for 2025/26) and a research training and support grant (RTSG). A limited number of studentships are available for international applicants, with the difference between 'home' and 'international' fees being waived by the registering university. Please note, however, that ARIES funding does not cover additional costs associated with relocation to, and living in, the UK, such as visa costs or the health surcharge.  

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