BBSRC SWDTP studentship: ‘Biological weapons’ and immunity in an invasive alien species

Supervisors:
Dr Jon Blount, Centre for Ecology & Conservation, Biosciences, University of Exeter
Dr Mike Birkett, Biological Chemistry & Crop Protection Department, Rothamsted Research, Harpenden
Prof Nick Smirnoff, Biosciences, University of Exeter

The harlequin ladybird (Harmonia axyridis) is a polyphagous alien invader in the UK, thought to pose a serious threat to natural enemy communities and the agro-ecosystem service they provide in terms of insect pest regulation. H. axyridis carries spores of obligate parasitic microsporidia, which are deadly pathogens for native ladybirds1. Intraguild predation is an important selective force amongst competing ladybird species, and it has therefore been hypothesised that H. axyridis owes its invasion success at least in part to microsporidia ‘biological weapons’, which infect and kill native ladybirds when they feed on H. axyridis’s eggs or larvae1. H. axyridis itself subdues microsporidia at an inactive spore stage, likely due to the alkaloid harmonine which is distributed throughout the body and eggs and has strong antimicrobial activity1.

The extent of the threat posed by microsporidia will depend on its transmissibility amongst ladybirds, and the fitness costs of microsporidial infection for H. axyridis. At high levels harmonine is known to be aversive to native ladybirds, and therefore we will test the influence of egg/larval harmonine levels on their palatability and consequences for interspecific microsporidial transfer. We will use GC-electroantenography (GC-EAG)2 to investigate how microsporidial infection may alter the semiochemical ‘signature’ of individuals, reception of such changes by conspecific and heterospecific intraguild predators, and how this may predict predation rates on eggs/larvae. Both parasitism and anti-parasite defences can be costly, and can trade against growth and reproduction. We will therefore test how microsporidial infection influences immune defences, and the consequences for growth and reproduction in H. axyridis. In these experiments we will experimentally infect individuals with microsporidia, and clear them of infection (as controls) using established methods.

The student will receive a multi-disciplinary training including animal ecophysiology, biochemical and molecular techniques, and key transferable skills. Specific training will be provided in maintaining insect cultures, quantifying behaviour, DNA extraction, gel electrophoresis, qPCR, sequencing and sequence analysis, microscopy, and GC-MS. The student will spend 6 months spread over years 2 and 3 at Rothamsted Research to carry out GC-EAG experiments.

This project has been shortlisted for funding by the BBSRC South West Doctoral Training Partnership (DTP), a collaboration between the Universities of Exeter, Bristol, Bath and Rothamsted Research institute. This project is one of a number that are in competition for funding. Studentships will be awarded on the basis of merit. The four year programme is designed to provide training in cutting edge world-class bioscience and food security research, including a structured first year of tailored taught courses and the completion of two laboratory rotations before progression onto the three year PhD. In addition, following the postgraduate training policy of the Biotechnology and Biological Sciences Research Council (BBSRC), all students will complete a three month professional internship, providing an invaluable experience of work outside of academic research. For further details about the programme please see http://www.bristol.ac.uk/swdtp/

Applicants for this studentship must have obtained, or be about to obtain, a First or Upper Second Class UK Honours degree, or the equivalent qualifications gained outside the UK, in an appropriate area of science or technology.

Application procedures:
Please upload the following documents to the studentship application form -
http://www.exeter.ac.uk/postgraduate/money/studentships/application/
• CV
• Covering letter (outlining your academic interests, prior research experience and reasons for wishing to undertake the project).
• Transcript(s) giving full details of subjects studied and grades/marks obtained (this should be an interim transcript if you are still studying)
• 2 references (if your referees prefer, they can email the reference direct to [Email Address Removed])

If you have any general enquiries about the application process please email [Email Address Removed] or phone +44 (0)1392 725150/723706/723310. Project specific queries should be directed to the primary supervisor.

The closing date for applications is midnight on Friday 10th January 2014. We anticipate that interviews will take place on the 10 and 11 February 2014.