The plight of the bumble bee

Guest post: Sive Finlay, a PhD student from Trinity College Dublin, recently won Best Biology student at the 2012 SET awards for her undergraduate project, “The plight of the bumble bee; diapause, immunity and parasitic attack”.

Here she explains the background to her project  and how the awards work

Bee populations are in severe decline, an alarming and worrying trend when you consider their vital importance as commercial and ecological pollinators. Research and media attention often focuses on afflictions of honeybees such as the Varroa mite and “colony collapse disorder”. However, parasites are also major contributors to the plight of the bumble bee.

Bumble bee queens spend six to nine months in diapause, a hibernation-like state which allows them to survive harsh winter weather. My research demonstrated that queens have reduced immune function during this time, leaving them vulnerable to infections and parasitic attack.

Sphaerularia bombi is a common yet poorly studied nematode which is found primarily in the Northern hemisphere, infecting up to 50% of queen bumble bees in some areas.

Adult female Sphaerularia present in the soil infect diapausing queens. My project showed that, with their immunological guards down, the queens cannot mount an effective response to invading parasites.

Sphaerularia exerts significant influence on its host after the queens emerge from diapause. The nematodes evert their uterus to a structure 300 times the volume of the rest of their body (3cm uterus compared to 1-2mm S. bombi body, see picture). This enormous uterus releases numerous eggs into the host and also extracts nutrients from the bees.

Sphaerularia castrate the queens so they don’t form new colonies. The parasite also changes queens’ behaviour so they go to sites suitable for diapause even though it’s the wrong time of year. Having released larval stage nematodes into the soil, parasitised queens die – while the nematodes are then poised to infect new queens entering diapause.

Sphaerularia clearly has a significant impact on a host with high ecological and commercial value yet it remains very poorly studied.  In collaboration with Joe Colgan’s PhD research at Trinity College Dublin and under the supervision of Professor Celia Holland, my project filled some of the gaps in our understanding of the molecular interactions between host and parasite.

One particularly interesting finding was that S.bombi infection seems to change the protein expression in bees, indicating a complex interaction between host and parasite at the molecular level in parallel to the dramatic physiological and behavioural changes in the bees.

About the SET awards

I was nominated by one of my lecturers, Dr Andrew Jackson, to enter this project into the European Science, Engineering and Technology (SET) student of the year awards.

There were over 500 applicants from science students across Europe, and I was lucky enough to be shortlisted as one of the top three students in the Biology category along with projects from Oxford and Cambridge.

I travelled to London to present my project and be interviewed by a judging panel from the Society of Biology, which was both intimidating and exciting! The awards were presented at an 0scars-style dinner ceremony at Kensington Town Hall.

I was delighted to win my category – it’s a great personal achievement but also a clear recognition of the high standard of student research and teaching at Trinity College.

Continuation of this research on a fascinating host-parasite system will bring us closer to understanding and hopefully eventually combatting the plight of the bumble bee.

• Sive Finlay is a PhD student in the Macroecology and Macroevolution research group at Trinity College Dublin. She is currently studying the ecology and evolution of tenrecs – a group of mammals native to Madagascar which have evolved convergent similarities to a wide range of unrelated mammal species. The project is supervised by Dr Natalie Cooper and funded by the Irish Research Council EMBARK Initiative.

Learn more

Read a press release about the awards by the Society of Biology and our previous article about the awards.