What is the justification for this work?

Efficient pollination by insects, especially bees, is critical to ensuring food security and yields of many crops. Production of soft fruit such as strawberries in the UK is worth around £360m annually, is growing year on year but depends heavily upon pollination by insects, particularly bees. When pollination is inadequate it frequently results in misshapen fruit. Owing to inadequate numbers of wild pollinators in agricultural ecosystems, strawberry growers rely heavily on commercially-bought colonies of bumblebees to try to improve pollination, but this is not always sufficient. Misshapen fruit must still be harvested despite poor sales potential in order to control pest insects that otherwise build up on them, so under-pollination causes a significant unwanted cost to growers.

Successful fruit production requires bees to carry pollen between flowers of the same crop species. Foraging bees often specialise on one species, which helps ensure this pollen transfer. Plants encourage this by providing distinctive cues such as unique flower odours, colours or shape which bees remember. Low doses of caffeine make bees remember cues such as floral odour more accurately, and increase bees' foraging activity.

What will the project involve?

This project will investigate whether it is possible to prime managed bumblebees on strawberry farms to prefer foraging on the flowers of the crop, in order to pollinate them more effectively.

The project will carry out experiments to test the ability of caffeine to improve crop pollination in field and laboratory settings. Bumblebees will be provided experimentally with caffeinated nectar alongside a synthetic strawberry flower's scent. Since caffeine improves bees' memory for the scents of flowers, the project will test whether these bees show increased foraging activity and attraction to strawberry flowers when they receive this priming treatment. We predict that if the preference of commercial bumblebees for strawberries is improved, the bees will visit more flowers, be more efficient at pollinating the crop and thus will enable the production of higher-quality, more valuable fruit.

Field tests of this technology will be performed on working farms using bumblebees to pollinate their strawberry crop, measuring fruit quality and yield resulting from this bumblebee-priming technology. The outdoor trials will also be supported by laboratory and semi-field experiments that optimise this system to get the best dose and timing of the priming system. A final economic assessment in consultation with the project’s collaborative private sector stakeholders who have invested in this research will consider the potential financial benefits to the farmer of using caffeine-primed bees.

What will be the benefit?

We anticipate that evidence for enhanced pollination services delivered by bumblebees will provide a compelling commercial opportunity that adds value to bee colony provision and could ultimately lead to enhanced pollination and fruit set in other pollinator dependent crop species.