Bumblebee conference broadens horizons

You can’t go out and see bumblebees anywhere other than on your doorstep these days, but that doesn’t mean you can’t hear all about them.  A couple of Saturday’s ago I joined a pan-European video conference and got what you might term ‘a continental pollinator fix’.

The European Bumblebee Conference subjects were many and varied, and truth be told I felt that I had been on a fantastic journey when the conference closed.  It is impossible to do them all justice here, so I can point you to them all online @ https://www.bestuivers.nl/hommelsymposium.

Vincent Kalkman of the Naturalis Biodiversity Centre of Leiden, chaired the conference, and opened proceedings by saying “Why he disliked bumblebees”. This proved a rather tongue-in-cheek title. He explained there were aggravating similarities between some species, and variations of colour within species, that make for difficult field identification between the likes of terrestris and pascorum.  He summed this up by saying “They seem easy to understand, but in fact their identification can drive you insane and understanding their requirements is mind-boggling!”  It was a good scene-setter for some great presentations.   

Challenges were the focus of the very first talk – ‘Mind the gap’ – by Bristol University’s Thomas Timberlake.

He highlighted the problem of seasonal floral resource gaps for bumblebees, particularly on farmland. Despite progress via Agri-Environmental schemes, the timing of floral resources remains an obstacle that future schemes could tackle.  Plant species have distinct flowering windows, which results in a seasonal pattern of nectar and pollen availability. Sometimes there is more than enough to go around, but at other times – like the early-spring and late-summer – there is a dearth of forage for bumblebees.

For bumblebees like this one (Bombus terrestris), it’s not just about how much food is available, it’s also when that food is available through the year. A dandelion flowering in early spring for example, would be more valuable to a bumblebee than an equivalent flower in mid-summer. Image: T. Timberlake 

Tom looked at foraging patterns of emerging queen bumblebees and young queens preparing for hibernation in farms in the South-West of England. The lack of September nectar on farms highlighted the potentially positive role of adjacent gardens as a consistent supply of nectar. 

How to boost resources in late summer?  Planting late-flowering cover crops, sowing margins with beneficial seed mixes, improving hedgerow quality, and introducing late flowering species (especially red clover, ivy and scabious) were all offered as actions which would have a positive effect.

Species which flower in September such as dandelions, red clover, ivy and scabious (clockwise from top left) are likely to be disproportionately important to bumblebees and other pollinators. Including these and other late-flowering species in conservation schemes will help fill the late summer hunger gap. Images: T. Timberlake & Wikimedia Commons

Paolo Biella gave us an inspirational update on bumblebees in the Alps. As a key part of bumblebee life-cycle is dedicated to collect resources, he intercepted Bombus terrestris returning to their nests which were, by scrutinising their pollen, found to be visiting 34 or so plant species, thus confirming their generalist feeding and how plant diversity is important for pollinator diet, even at high altitude.

More than 50% of Europe’s bumblebee species are found in the Alps – that’s around 39 species. – despite the area accounting for around just 10% of Europe’s surface. Paolo looked at the habitat requirements of three alpine species to see if any distribution changes could be identified in since the 1980s. Temperatures in the areas studied have risen, narrowing environmental resources to cold-adapted bumblebees and making them more sensitive to changes. All three were shown to be feeding at higher altitude now.

Given that the Alps is a core area for many European bumblebees, it was a sobering and thought-provoking presentation.

Working in partnership was a constant theme across the presentations. This came across vividly in the presentation by Nikki Gammans (Bumblebee Conservation Trust) which was a practical exploration of working with farmers. 

Based around the reintroduction of the Short-haired bumblebee, Nikki explained that Kent is the UK’s hot spot for rarer bumblebee species and that they tend to be late emerging and longer tongued, factors that influence targeted habitat creation. 

The aim was to work on a landscape scale, and this could only be effectively done by connecting working farms. Connections provided by Natural England opened up avenues to explore agri-environment schemes and the options for individual farms by giving bespoke advice. 

Management and maintenance methods were explored to enhance the prospects for flower-rich meadows. Grazing regimes, field margins, cutting cycles, seed mixes and rotation of stock also fell under the spotlight. The honest appraisal that patience is essential for work that can take between 5 and 9 years to show significant changes, and acknowledging the value of advice from the farming community, wrapped up a most impressive talk.

Indeed each and every one of the talks was inspirational and educational. From the Netherlands, to the Himalayas, via the Alps and the south of England.  Too much ground was covered for me to capture it all in a short blog, but hopefully the above gives a flavour of what was presented and encourages you to log in and explore:

To see the presentations visit https://www.bestuivers.nl/hommelsymposium.

About the organisers: Based in the Netherlands, the European Invertebrate Survey (EIS Foundation) shares knowledge on insects and other invertebrates and conducts and promotes research to aid policy and management to help insects in The Netherlands. More at  https://www.eis-nederland.nl