PhD Research Project: How does climate influence insect responses to pesticides? - A key question f

Background: As poikilotherms the body temperature of insects is directly determined by environmental conditions. Thus, microclimate temperature profiles, which are often highly variable, will dictate rates of metabolic activity and development as well as behaviour. Temperature also influences the toxicokinetics of pesticides, i.e. how an insect processes toxic compounds. Yet the impact of climate on pesticide response mechanisms remains poorly understood despite being key to improving food security. A core aspect of any integrated pest management (IPM) plan, and minimising impacts on beneficial insects such as pollinators, must be to understand how changing environmental conditions will impact upon the efficacy of pest control measures at different seasonal time points. This includes extreme events given their predicted increasing frequency under climate change models.

The few studies conducted to date suggest responses can be variable, for example the toxicity of pyrethroid insecticides is generally thought to increase at low temperature as a consequence of a reduced ability to biotransform the toxic parent compound at cooler temperatures [1]. However, the toxicity of other pesticides, such as dimethoate and chlorpyrifos, actually decreases as temperature declines [2]. Very recent research in the Hayward lab has identified that neonicotinoids can potentially impair stress responses at both high and low temperature, as well as impact on DNA damage.

Examining the toxicokinetics of different pesticides on key pest species (as well as beneficial insects such as pollinators) across a range of treatments, rather than a single ‘standard' test temperature, is crucial to improving IPM, and helping ensure pesticides are applied using minimum effective doses. Identifying what molecular processes are disrupted by temperature also provides a route for new targets for pest control.

Objectives: Our overall aim is to evaluate the influence of temperature on the toxicity of pesticides and identify what components of the toxicokinetic response are being disrupted. We will examine how temperature:

1. Interferes with core stress response gene expression mechanisms using RNAseq.
2. Alters the role of detoxification enzymes.
3. Influences levels of pesticide-induced DNA damage.
4. Examine sub-lethal effects on pest development and fecundity.

The insect species and pesticide(s) to be investigated will be decided through discussion with the PhD candidate and other stakeholders. We have extensive experience of culturing a broad range of insects in the Hayward lab - including Diptera, Hymenoptera (bees), Lepidoptera and aphids etc. [3-5].

Outputs from this fundamental and applied research will have direct applications in enhancing the use of existing pesticides, minimising the impact on non-target species, as well as identifying potentially novel targets for new pest control products.
Hayward, Hodges and Orsini are all based within the Biosystems and Environmental Change (BEC) theme, and the DR will interact on daily basis with researchers at the vanguard of applying diverse approaches to understanding organismal responses to environmental change.

The DR will receive training in the use of extensive insect culturing and climate control facilities, as well as state-of-the-art omic technologies. Specialist training will be given in high throughput sequencing (RNA-seq), spanning sample extraction to bioinformatic analysis of the data generated. Training will also be given in Comet assays to examine DNA damage, as well as enzyme assays, e.g. EROD assay.

There is huge scope for stakeholder and public engagement/impact.

Funding Notes

This project is fully funded through the BBSRC Midlands Integrative Biosciences Training Partnership (MIBTP): https://warwick.ac.uk/fac/cross_fac/mibtp/pgstudy/phd_opportunities/

Eligibility requirements: https://warwick.ac.uk/fac/cross_fac/mibtp/pgstudy/phd_opportunities/application/

References

1. Weston et al. (2009) Environmental Toxicology and Chemistry 28: 173-180. 2. Jegede et al. (2017) Ecotoxicology and Environmental Safety 140: 214-221. 3. Coleman, Bale and Hayward, (2014) Journal of Experimental Biology 217: 1454-1461. 4. Pateman, Hill, Hayward and Thomas (2016) Global Change Biology 22, 556-566; 5. Owen, Bale, and Hayward (2016) Apidologie 47:66-75