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Greater food security under environmental change through molecular characterisation of pollinator dormancy (diapause)

Principal Supervisor: Dr Scott Hayward - School of Biosciences

Co-supervisor: John Colbourne

PhD project title: Greater food security under environmental change through molecular characterisation of pollinator dormancy (diapause)

University of Registration: University of Birmingham

Project outline:

Establishing agricultural resilience and food security in the face of environmental change is of intense global interest, and pollinators play a key role in achieving this objective. Agriculture cannot rely on natural pollinator populations alone, as many of these are in severe decline. Thus, pollination service provision in the UK is dependent on the commercial production of key species such as the bumble bee Bombus terrestris. It is estimated that the global economic value of pollination service is US$215 billion or 9.5% of global food production value in 2005 (Gallai et al., 2009).

In common with most temperate insects, B. terrestris enters a period of dormancy, termed diapause, to survive winter under natural conditions. More uniquely, only mated queens enter diapause and persist to establish new colonies the following year1. Insect diapause is a pre-emptive response, typically induced by changes in day/night length long before winter, and involves a suite of synchronised behavioural and physiological changes that modulate development and reproduction, longevity, starvation and stress responses. Diapause persists for many months (for years in some species), but can be disrupted by climate warming2. To date, there are very few published studies on the molecular processes underpinning the diapause programme in B. terrestris3. Indeed our understanding of diapause in all bee species is scant compared to other insect models4. This project seeks to identify the key molecular processes underpinning diapause in B. terrestris, as well as how temperature and diet influence diapause characteristics, including incidence, duration, stress tolerance and post-diapause fitness.

A draft genome sequence is assembled and annotated for B. terrestris, and recent advances in high-throughput cDNA sequencing (RNA-seq) can reveal new genes and splice variants and quantify expression genome-wide in a single assay. In addition, RNAi knockdown has been successfully employed in this species4, permitting functional analysis of transcripts uniquely regulated within the diapause programme. Thus, B. terrestris represents an ideal system to dissect mechanisms of diapause regulation and stress tolerance. Interestingly, diapause is also thought to be closely linked to the evolution of insect sociality.

In a commercial setting, diapause is extremely useful as it allows the long-term cold storage of bees. However, diapause can also represent an unwanted delay in population turnover. Currently, commercial providers have a very limited understanding of how to manipulate the diapause state, or the molecular mechanisms that underpin key diapause characteristics – which represent potential targets for manipulation. Yet this has fundamental applications in controlling life cycle duration, synchronising availability with demand, providing a year round supply ‘off-the-shelf’, as well as maximising the fitness of supplied bees.

Core objectives are to:

  1. To characterise key gene expression changes underpinning the diapause programme in B. terrestris.
  2. Determine the impact of temperature and diet manipulations on diapause incidence, duration and post-diapause fitness, as well as changes in gene expression.
  3. Develop new molecular and physiological methods to enhance commercial pollinator culturing practises.

References: 

  1. Owen, E. L., Bale, J. S. and Hayward, S. A. L. (2013) Can winter-active bumblebees survive the cold? Assessing the cold tolerance of Bombus terrestris audax and the effects of pollen feeding. PLoS ONE 8: e80061
  2. Bale, J. S. and Hayward, S. A. L. (2010) Insect overwintering in a changing climate. Journal of Experimental Biology 213: 980-994.
  3. Amsalem et al (2015) Conservation and modification of genetic and physiological toolkits underpinning diapause in bumble bee queens.
  4. Rinehart et al. (2007) Upregulation of heat shock proteins is essential for cold survival during insect diapause. PNAS 104: 11130–11137

BBSRC Strategic Research Priority: Food security

Techniques that will be undertaken during the project:

Both SH and JC are based within the Biosystems and Environmental Change (BEC) theme, and the DR will interact on daily basis with researchers at the vanguard of applying systems biology approaches to understanding organismal responses to environmental change. The SH lab has extensive experience in working with many different insect systems, including ongoing projects with B. terrestris. 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 of B. terrestris transcripts (RNA-seq), spanning the processes from sample extraction to the bioinformatics analysis of the data generated. Training will also be given in the use of RNAi to knock-down the expression of diapause-associated transcripts. Through collaboration with/exposure to established industry partners involved in the commercial production of pollinators, the DR will also gain unique training at the interface of academic biological research and industry.

Contact: Dr Scott Hayward, University of Birmingham