5 September 2023

Finding the best trees for bees

From tree traps to nature apps, find out how we're researching the benefits of biodiversity for bees this summer.

By Jessica Hayne

Two bumble bees on globe thistle flowers, and one in the air.

There are over 20,000 different species of bee around the world, and 270 in the UK alone. But wild bee populations are in decline.  

As we lose more and more biodiverse habitats, resources such as pollen and nectar for bees dwindle.

Through our Nature Unlocked research, we’re working to understand the trees and plants that encourage the highest abundance of pollinators. With this information, we’ll be able to inform urban landscape planning and bring the buzz back to our environments.  

Three scientists stand in a field, moving around insect nets.
Pollination research, Jim Holden © RBG Kew

Looking up 

Whilst there have been many studies over the years focusing on pollinators, very few have looked at the value of trees within pollinator communities.    

With a new pollination research team in place, we’re using Wakehurst’s diverse habitats as a living laboratory, to understand which trees and plants are providing the most benefits for pollinators.  

Over the summer, the team set out traps both within trees and across grasslands, to see which plants, trees and habitats attract different invertebrates. Where possible, they’ll take pollen samples to see where else the pollinators have been exploring. The insects are then taken back to the Millennium Seed Bank laboratories, where the team can take a closer look and identify the species.  

Elsewhere, transect walks and regular insect identification are helping to build the full picture of Wakehurst’s pollinator population. 

A scientist hangs a plastic bee tree trap on a branch.
Pollination research, Jim Holden © RBG Kew
A bee in a small plastic pot
Pollination research, Jim Holden © RBG Kew

With solitary bees checking into hotels across the gardens, pollen samples from their larvae nests can easily be taken without disturbing residents. Only a small amount is needed to understand where the bees have been, and in particular which trees they’ve taken a fancy to.  

A small metal spoon scoops pollen out of a bee hotel tray.
Pollination research, Jess Hayne © RBG Kew

Engaging Citizen Scientists 

For the next stage of Trees for bees, we’re turning to you.  

In order to fully understand what our pollinators are foraging at Wakehurst, we need your help!  

We’ve curated special walks around the gardens, focusing on key plants and areas that we want to investigate. The study invites you to take pictures of the insects you see on different trees and across wider habitats, which will all go into a database for our scientists to use. Just download the iNaturalist app, pick up a Trees for bees guide on your next visit and get monitoring!  

Find out more about the Trees for bees study here

A woman holds a leaflet, which features a picture of a bee and a map.
Trees for Bees, Visual Air © RBG Kew
A green metal sign in front of a woodland path reads 'Trees for Bees: Pinetum (south path)
Trees for Bees, Jim Holden © RBG Kew

Pollinator paradise 

Although we’ve set out a curated route for our Trees for bees study, our pollinators can be found all over. 

Open woodlands and flower-rich meadows provide the perfect spot for pollinators, and areas such as Coronation Meadow and Bloomers Valley offer a sensory treat, for both insects and humans alike! Take in sweeping vistas, listen out for the symphony of insect sounds and see who you can spot buzzing around our native wildflowers. Its grassland cousin, the American Prairie, also provides pollinators with an appetising spread of non-native species, the subject of a Nature Unlocked study last year. As many non-native species flower later than native meadows, these are especially important for UK pollinators, extending the nectar resources beyond a typical season. 

A butterfly on a blackroot flower.
Pollinators at Wakehurst, Jim Holden © RBG Kew

These are a few of our favourite bees 

Although bees may get a bad reputation in Maria’s The Sounds of Music number, we think our pollinator pals are pretty impressive. 

With so many species buzzing around the UK, including 24 bumblebees, we asked our experts which are their favourites and why.  

Research Lead, Phil Stevenson shared: 

‘My favourite bee is the Sainfoin bee (Melitta dimidiata). This is one of the UK's rarest bees with records confined to a few sites in the Salisbury Plain area. It is restricted to feeding on Sainfoin (Onobrychis viciifolia) which is especially exciting for us at Kew as it is one of the plants where we have discovered natural plant compounds in the nectar with medicinal properties for bees. The Sainfoin bee is also a great example of a monotectic bee - a specialist bee that only feeds from just one species of plant. This illustrates how fragile some populations of bees are and why it is so important to have flower diversity – if we don’t have Sainfoin flowers we don’t have Sainfoin bees.’ 

Katie Berry, Research Assistant: 

‘My favourite is the Early bumblebee, (Bombus pratorum). As the name suggests, these are often one of the first bumblebees to emerge in early spring. Seeing these colourful little guys reminds me that summer isn't far away!’ 

A Sainfoin bee (Melitta dimidiata) on a pink flower
Sanfoin bee, Hauke Koch © RBG Kew
An Early bumblebee, (Bombus pratorum) on a white flower.
Early bumblebee, Hauke Koch © RBG Kew

Dr Janine Griffiths-Lee, Post-doc Research Associate: 

‘My favourite bee is the Ashy Mining Bee, (Andrena cineraria). They are just so beautiful and distinctive, with ash-grey hairs and a glossy blue-black abdomen. They nest in the ground by excavating small tunnels and close the entrance holes to the burrows when they have finished foraging for the day.’ 

Rachel Wilkinson, Research Assistant  

‘My favourite bee is Bombus vestalis, the Southern cuckoo bee. It's so interesting how these guys lay their eggs in the nest of Buff-tailed bumblebees (Bombus terrestris) similar to cuckoo birds to avoid rearing their own young. I find that really fascinating.’ 

An Ashy Mining Bee, (Andrena cineraria) on a yellow flower.
orangeaurochs Flickr, CC BY 2.0
A Southern cuckoo bee (Bombus vestalis)
Southern cuckoo bee, Hauke Koch © RBG Kew

As science continues across our gardens, keep an eye out for our scientists, and of course pollinators!  

Read & watch

A man in a green Nature Unlocked t-shirt pushes a ground LiDAR machine on wheels

Nature Unlocked

The Landscape Ecology Programme at Wakehurst: researching the value of UK biodiversity to inform nature-based solutions to critical challenges such as climate change and food security.