Multi-trophic impacts on the supply of a key ecosystem service: economic and ecological impacts of parasites on pollination
Pollination services are essential for at least a third of the world’s crop production contributing national and global value of ~£430 million and €153 billion, respectively, per annum. In addition, pollination is essential for flowering plants in natural and semi-natural ecosystems. The majority of pollination services, particularly in crops, are supplied by wild and managed populations of bees. Consequently, this pollination service is threatened by dramatic global declines in wild bee populations, and in Europe and North America by declines in managed honey bees.
In addition to direct impacts of declines on pollination services, indirect impacts may result from the drivers of these declines. A key driver of declines in managed honey bees, and managed and wild bumble bees, is emergent disease. Commercially produced bumble bees provide a key pollination service to crops such as soft fruits (e.g., strawberries, blueberries, etc.) and tomatoes, with more than 1 million colonies being exported globally each year, and over 60,000 to the UK alone, an investment by UK growers of ~£3 million per annum. However, commercial bumble bees also carry a range of parasites, from viruses to fungi, with evidence for their emergence in wild bumble bee populations in North and South America, and most recently in the UK and Ireland. While parasites and disease may impact on pollination by reducing the number of pollinators available to provide this service, they may also have less obvious, but equally significant effects, through impacts on the behaviour of pollinators. Previous research in bumble bees has shown that parasitized individuals are cognitively impaired (have a reduced learning ability), have reduced foraging rates, exhibit higher fidelity to, and forage on different, flower type(s). However, the impact of these effects on pollination service in crops remains unknown.
In this project, we will address 4 key questions:
What impacts do native and emergent parasites have on the flower-visiting behaviour and pollination services of bumble bees in key UK soft-fruit crops?
What impacts do these parasites have on the behaviour and pollination services provided by bumble bees to wildflowers used in agri-environment schemes?
What is the current biological impact of parasites in commercially supplied bumble bees on their pollination value to UK growers in the production of class 1 fruit across different cropping systems (bed vs. tabletop polytunnels)?
What is the economic impact of parasites on commercial pollination services? How can commercial users combat this impact? How can this information inform UK government policy and action?
This work is funded through a BBSRC-Case studentship