Supervisors: John Carr (Plant Sciences) and Beverley Glover (Plant Sciences)
Importance of the area of research:
The project links two important areas of research: plant-virus interactions and bee-plant interactions. Studies of plant-virus interactions are dominated by studies on the effects of these agents on crop plants – understandably, since viruses cause serious crop diseases and decreased yield. But there is a growing school of thought that in wild plant communities plant viruses may sometimes function as mutualistic symbionts. For example, viruses may ‘pay-back’ susceptible hosts by attracting pollinating bumblebees or enhancing the resilience of plants to drought or cold (see Groen et al. 2016 and references therein). Many wild and cultivated plants depend on bee-mediated pollination. However, bee populations and diversity are endangered by disease, environmental change and anthropogenic factors. To mitigate the ensuing loss of pollination activity requires among other things a deeper understanding of the mechanisms – including those affected by plant pathogens and mutualists – that shape bee-plant interactions.
Infection of tomato (Solanum lycopersicum) plants by Cucumber mosaic virus (CMV) altered bumblebee (Bombus terrestris) foraging behavior; infected plants were more attractive to these important pollinators. Bumblebee-mediated ‘buzz-pollination’ enhances the number of seeds produced and facilitates pollen export. Mathematical modelling suggests that pollinator bias favours reproduction of susceptible over that of resistant plants. We hypothesized that under natural conditions viruses enhance susceptible plants’ competitiveness and inhibit propagation of resistant plants. This may be good for viruses and their susceptible hosts but why would bumblebees display this innate preference for virus-infected plants unless they derive some benefit?
What the student will do:
The student will test the hypothesis that visiting virus-infected plants is beneficial to foraging bumblebees. Tomato provides pollen to bumblebees: a protein source that the insects feed to their larvae. Therefore, we will examine the effects of virus-infection on bumblebee interactions with CMV-susceptible hosts that provide pollen and nectar rewards (Phaseolus vulgaris and Antirrhinum majus). There are two likely ways in which virus infection could benefit bees: through increased nutritional rewards or through increased provision of beneficial low molecular weight plant secondary metabolites (e.g. phenolics, see Mao et al. 2013). The student will: 1. Perform behavioural assays (Groen et al. 2016) to determine if CMV infection renders nectar-providing plants more attractive to bumblebees; 2. Determine if infection alters visual and olfactory cues available to foragers; 3. analyse the volume and sucrose content of nectar; 4. Pollen protein content, and 5. amino acid and phenolic content of pollen and nectar.
Please contact the lead supervisor directly for further information relating to what the successful applicant will be expected to do, training to be provided, and any specific educational background requirements.
Groen, S.C., et al. 2016. Virus infection of plants alters pollinator preference: A payback for susceptible hosts? PLoS Pathogens 12(8): e1005790. doi:10.1371/journal.ppat.1005790
Mao, W., et al. (2013) Honey constituents up-regulate detoxification and immunity genes in the western honey bee Apis mellifera. Proceedings of the National Academy of the United States of America 110: 8842–8846.
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