International PhD scholarship: Evolutionary biology, cooperative virulence and the improvement of biological control agents

High virulence is the most important trait for microbial biocontrol agents. More efficient lethality at lower doses has dramatic consequences for efficacy and for the cost-effectiveness of biopesticides. Typically, researchers have relied on ‘bio-prospecting’, the search for novel strains or species in order to isolate strains that are effective pest control agents. However, in many cases (e.g. for Bacillus thuringiensis) the number of really effective strains is limited and challenged by the evolution of resistance. In other instances, effective strains can be found, but virulence may deteriorate in the laboratory culture for poorly-understood reasons.
For the last decade work in the Raymond lab has sought to understand how selection for high and low virulence in microbial biological control agents operates. We have found that social evolution theory has tremendous predictive power for understanding microbial virulence [1, 2]. In brief, investment in virulence can be costly to individuals via invested in exported proteins, which can be exploited by faster growing cheaters (public goods cooperation). Conversely, for some enteric parasites virulence is associated with increased replication rate, but excessive growth rates limits the productivity/fecundity of groups and reduces parasite success via a tragedy of the commons.

We have developed and tested social evolution of virulence in multiple insect / parasite systems including Bacillus thuringiensis and Lepidoptera [3], entomopathogenic nematodes and Coleoptera [4], enteric microbes and Lepidoptera and have working models of infection and passage in enteric microbes of Anopheles gambiae. Published work has illustrated the importance of social evolution in maintenance of virulence [4] , while ongoing research has shown that we can evolve strains that can substantially overcome resistance to B. thuringiensis and recover effective infectivity.

Through the University of Exeter international scholarship the PhD applicant would be able to develop a research proposal targeted at improving the virulence of a microbial biocontrol agents. While we would prefer applicants to work with established experimental systems we are generally interested in developing or improving virulence in host and parasites that can be readily cultured in the laboratory. Applicants interested in mosquito symbionts, Bacillus biopesticides, and insect pathogenic nematodes are particularly welcome. Applicants with a theoretical interest in the evolution of virulence or social evolution are also encouraged.
Research environment. The Penryn campus is situated in the far west of England in an area of outstanding natural beauty. We have newly built microbiology laboratory, access to insect quarantine facilities and high spec facilities at the Environment and Sustainability Institute. The laboratory is funded by grants and studentships from BBSRC, MRC and the Leverhulme Trust investigating the improvement of biocontrol strains and the evolution of resistance to pesticides and antibiotics.
Funding notes. International (non-EU / UK ) applicants only. Applicants must apply competitively for funding via the University of Exeter’s international Excellence scholarship scheme http://www.exeter.ac.uk/postgraduate/money/fundingsearch/awarddetails/?id=2461. This scheme will pay bench fees, tuition and maintenance for up to 3.5 years. Applicants are strongly encouraged to contact [Email Address Removed] before 15 Dec 2016 in order to discuss and develop a detailed research proposal.