Project highlights

  • Pesticides are vital for their role in food security, but thorough regulatory testing is required to ensure they are safe for both human health and the environment
  • Regulatory tests are strict in their design and not always environmentally realistic. In this project you will investigate how pesticide degradation in rivers will be altered in a changing climate, with a focus on temperature effects on persistence
  • You will use a wide range of modern chemical and molecular ecological analyses and techniques in combination with bioinformatics, to gain a broad overview of pesticide regulatory regimes.


Pesticides are essential in crop production due to their role in improving crop productivity and food security. Before being granted approval for use, pesticides are subject to regulatory evaluation using a framework designed by the Organisation for Economic Co-operation and Development (OECD). These tests provide evidence of the extent a pesticide persists in the environment and the risks they pose. Although valuable, the tests are conducted under laboratory conditions, which often lack environmental realism and therefore may not accurately reflect pesticide fate and transformation in the real world.

Previous research has shown that when environmental inoculum is taken at different times of year but incubated under the same conditions in the laboratory, pesticide degradation is slower when temperatures were colder in the real environment. Microbial degradation is one of the most important processes in determining pesticide fate and it is unclear if these differences in degradation are due to specific microbial communities not being present at colder times of year, or whether microbial consortia are acclimatized to colder temperatures and therefore are not as active at the higher laboratory temperatures.

Understanding the complexities and interactions of temperature effects on pesticide fate and transformation would provide information to guide regulatory approval of new chemicals and could aid the design of tests used to investigate the environmental fate of pesticides. It would also provide insight into how the microbial communities responsible for pesticide fate and transformation will be affected by a changing climate.


University of Warwick


  • Climate and Environmental Sustainability


Project investigator

Professor Gary Bending, University of Warwick ([email protected])


How to apply


You will compare pesticide degradation under incubation temperatures of traditional OECD test designs with temperatures more closely aligned to those at the time of environmental inoculum collection from rivers. To determine pesticide degradation, you will use a range of analyses, including liquid chromatography-mass spectrometry. This will be complemented with molecular profiling of microbial communities, including metagenomic analysis, to provide an understanding of how pesticide degradation is linked to the microbial communities present, e.g. are there certain communities which are present or more active and which accelerate pesticide degradation when it is warmer in the real environment. Further work will investigate testing the effect of temperature acclimatization periods on the environmental inoculum prior to testing pesticide degradation.

Training and skills

Students will be awarded CENTA2 Training Credits (CTCs) for participation in CENTA2-provided and ‘free choice’ external training. One CTC equates to 1⁄2 day session and students must accrue 100 CTCs across the three years of their PhD.

Training will be provided in a range of chemical analyses as appropriate (e.g. HPLC, TLC, LC-MS), molecular techniques (DNA extraction, PCR, sequencing), metagenome sequencing, and bioinformatics.

Partners and collaboration

An internal research proposal at Syngenta has been submitted and a decision on the proposal is expected by January 2023. If successful, the student will be required to partake in a minimum 3-month placement with Syngenta at their Jealott’s Hill International Research Centre and this will provide valuable industry experience for the student.

Further details


Professor Gary Bending, School of Life Sciences, University of Warwick, CV4 7AL


[email protected]

Information and links at the following webpage:

If you wish to apply to the project, applications should include:

  • A CV with the names of at least two referees (preferably three and who can comment on your academic abilities)

Applications to be received by the end of the day on Wednesday 11th January 2023. 

Possible timeline

Year 1

Multiple experiments at different times of year assessing pesticide degradation under standard regulatory test regimes and more environmentally relevant temperatures.

Year 2

Determine the impact of laboratory equilibration times on pesticide degradation.

Year 3

Determine microbial taxonomic and functional characteristics which control temperature induced differences in pesticide fate and transformation.

Further reading

Southwell, R. V., Hilton, S. L., Pearson, J. M., Hand, L. H. and Bending, G. D. (2020) ‘Inclusion of seasonal variation in reiver system microbial communities and phototroph activity increases environmental relevance of laboratory chemical persistence tests’, Science of the Total Environment, 733 (139070).


The project will comprise a mix of field work, laboratory work and desk based bioinformatic analysis. During any lockdown periods, bioinformatic components of the project will become the focus of the programme.