Cucurbit pollination: mechanisms and management to optimise field crop quality and quantity


CP 118 - Cucurbit pollination: mechanisms and management to optimise field crop quality and quantity

Start Date: 
Completion Date: 
Project Leader: 
Dr Juliet Osborne, University of Exeter
CP 118

Industry representative: Ellis Luckhurst, P.E. Simmons & Son Ltd

HDC project cost: £67,878


The Problem:

Most cucurbit crops require insect pollination to set fruit, and their production in the UK has been steadily increasing over recent years, due to demand from supermarkets and their increasing popularity as part of a healthy diet. Although not grown over large areas, they are high value crops and the quality of each ‘fruit’ is important to market value. They are also a traditional and popular choice for allotments and gardens and part of the recent trend to “grow your own”. To ensure productive and sustainable yields, it is important to understand whether the dynamics of pollination are affecting yield quality of quantity in the UK.

This project focuses on the pollination dynamics of field-grown courgettes (Cucurbita pepo) as a model species for cucurbit crops, in collaboration with a local grower P.E.Simmons & Son (Cornwall). It will investigate the effectiveness and abundance of pollinators in the UK, to determine whether pollination is limiting crop quality or quantity and if so, under what conditions. In its native range Cucurbita pepo is pollinated by specialised squash bees (Peponapis species) which do not occur in the UK, so this studentship will question how effective our native insects are at pollinating the crops. Ways of improving pollination within field systems will then be explored, for example by considering the introduction of honeybee or bumblebee colonies; or by introducing wild flower strips into the fields to provide extra forage for the bees (which could have a positive or negative effect on courgette flower visitation).


Aims and objectives:

These are listed as a series of questions that the student will answer (in year 2 and 3, choices between the options will be made depending on results to date, advice from industry and resources available).

Year 1:
1. What are the most effective wild pollinators of field-grown courgettes in South West UK in terms of abundance, visitation rate and pollen transfer efficiency?
2. Does pollination deficit limit yield (number, quality of fruits)? If so, under what environmental conditions?

Year 2:
3. Does the introduction of honeybee colonies (or commercial bumblebees) improve pollination and consequent yield?
4. Does the introduction of a flower strip between rows or along a field edge alter the effectiveness of pollination? If pollinators are supported with other floral resources do they visit the courgette flowers more (attraction) or less (distraction)?

Year 3:
5. Is there an interaction between water use (or nitrogen use) and pollination levels?
6. How do the findings on pollination in field-grown courgettes compare with courgettes grown in allotments and gardens (which might have larger bee populations – Osborne et al, J Appl Ecol 2008)?