Conserving insect pollinators in our countryside

In our guest blog today Dr Lorna J Cole, Agricultural Ecologist, Scotland’s Rural College (SRUC), talks about how a diversity of well-connected, floristically-diverse, habitats will help to ensure that our countryside supports healthy pollinator populations 

Diversity of habitats found in our countryside.

Insects that pollinate our flowers require a diversity of plants to sustain healthy populations. Plants provide pollinators with sugar-rich nectar to fuel flight and protein-rich pollen to help rear larvae. In return, flower visiting insects transfer pollen supporting plant reproduction. Foraging pollinators seek specific flowers to meet their nutritional demands, for example, knapweed and thistles are rich in nectar whereas clovers have protein-rich pollen. As plant species flower at different points in the season, a diversity of flowering plants is required to ensure a continuous supply of pollen and nectar.

Ringlet on Greater Birds Foot Trefoil

Different habitats support different flowering plants. Just think of heather moorland with its variety of heather species, bog asphodel and blaeberry, or species-rich grasslands colourful with ragged robin, devil’s bit scabious and red clover.

With many pollinators being highly mobile they can move between habitats, searching for food. Little is, however, known about how pollinators track food resources in a landscape. To try and shed some light on this, researchers at SRUC established a landscape scale study. The two key aims of the study were:

• To investigate which habitats provided key foraging resources for pollinators
• To determine how the value of these habitats changed through the flowering season

Common Carder (Bombus pascuorum) on knapweed

The research found that habitats showed clear differences in botanical diversity with road verges, buffer strips and scrub providing particularly rich foraging habitats. Peak flowering times varied between habitats indicating that their potential to provide food differed during the season. Pollinators tracked floral resources at the landscape scale, dynamically switching to the most profitable foraging habitats.

This research highlights that the conservation of insect pollinators requires a landscape scale approach. A diversity of well-connected, floristically diverse habitats will help to ensure that our countryside supports healthy pollinator populations and protect the pollination services that they provide.

Tales from the Taynish Trail

Caroline Anderson regularly visits Taynish National Nature Reserve with her camera. The recent addition of a pollinator trail on the reserve has added a little more interest, and in this, the second of her regular updates, she takes a stroll and reports back on what caught her eye.

Up early and off to Taynish  to walk the Pollinator Trail.  Another stunningly beautiful day – does it ever rain at Taynish? 😊    The early morning air was a bit nippy, so I was hopeful of catching the insects before they warmed up their wings and were too flighty.  As if on cue, at the first new bench along the track, there was a Large Red Damselfly basking in the sun.

It’s always a good sign when you see insects so close to the beginning of the trail, it means they will be plentiful at the lochan and in the woods.   Along the boardwalk, and with a little bit of bog jumping,  I noticed the Blue-tailed Damselflies are back now too.   They are quite entertaining wee things – avoiding the camera wherever possible.  Bit of a hiding fail for this one though!

Also hidden in amongst the heather by the boardwalk was what looked like a wasp’s nest.  Funnily enough I didn’t investigate that one too closely.

As I continued along the path I spotted a Drinker Moth caterpillar hiding in one of the tussocks.  They are believed to drink dew hence the name Drinker.  The moths are very beautiful and  can range from buff colour to reddish-brown – one to look out for in July and August.

Next stop the picnic tables, usually a good area for butterflies and damselflies and perhaps the source of the wasp’s nest up at the boardwalk.  This one was happily stripping the fibre from Gordon’s shed!

In the wood alongside the burn, the butterflies were stirring, Orange Tips and Speckled Wood flying amongst the trees and bracken and warming their wings in the early sun.

Down on the shore this little bee was enjoying the Red Campion.  There is certainly no shortage of floral opportunity around just now – which is great news for so many insects.

On the way back to the car park, I took a wee detour up through the wood beside the sluice to the Mining Bee site, just to check if there was any activity at the upturned tree root.  No Mining Bees to be seen just yet, but to my surprise and delight, I saw the first Four-spotted Chasers of the year and an abundance of Large Red Damselflies.

Insects are absolutely fascinating, from the tiniest fly to the largest dragonfly.   Water Boatmen can walk on water, Monarch butterflies can fly thousands of miles, dragonflies have been on earth for millions of years, and bee’s wings beat at 190 times a second!   Incredible!

 

Find out more about Taynish National Nature Reserve

 

Orkney options for pollinators

Providing for pollinators is a nationwide drive as far as Scotland is concerned. From the Scottish Borders, to the Northern and Western Isles, there are plenty of projects underway to help our hard-pressed pollinators.

Take Orkney for example.

Orkney Islands Council is working in partnership with the Orkney Alcohol Counselling and Advisory Service (OACAS) and SUSTRANS to upgrade an under-utilised area of open space in the town of Kirkwall. The aim is to create a space which will be of great benefit to both people and pollinators.

Orkney is rightly famed for its marvellous coastal scenery

As an increasingly popular cruise ship destination with over 9,000 inhabitants of its own to accommodate, Kirkwall is very much the capital of Orkney, and not surprisingly, quality greenspace within the town is valued by residents and visitors alike.

That’s why work to develop 33,000 square metres of Arcadia Park next to the new Balfour hospital has captured the local imagination. During the first year, over 8000 m² will be sown with a pollinator-friendly mix of cornfield annuals and perennial wildflower species.  Trees and shrubs are being planted at the moment and the park also includes three small ponds with locally sourced aquatic plants. Local volunteers have been crucial in tackling a range of planting and landscaping needs.

This is all good news for pollinators in Orkney, one of the small numbers of areas that can claim to be home to the rare great yellow bumblebee, Bombus distinguendus.

In Scotland, the great yellow bumblebee is strongly associated with flower-rich machair habitats on the north-west coast, but it is also found in association with more conventional agricultural systems of Orkney and Caithness.

A bank of flowers near Pickaquoy Leisure Centre

The park is close to Foreland Road, which was completed as recently as 2016. Here a sustainable urban drainage system vies for attention alongside wetlands, a pond and meadow areas, all sown / planted with locally sourced wildflower seed and plants.

The new Balfour Hospital is due to open in June 2019 and the addition of landscaping which includes trees and wildflower areas is bound to be a boon to the growing ‘natural health service’ drive.

Pollinators being catered for at Stromness Primary School

With some 70 islands Orkney relies heavily on its natural heritage economically. For some years now, the value of assets such as maritime heath and grasslands, as well as seemingly less-promising areas such as roadside verges, has been acknowledged. Now with parks and gardens being added to the equation the picture just got that bit rosier for pollinators and, of course, people.

(With grateful thanks to Eileen Summers, Environmental Officer (Policy), Orkney Islands Council.

Find out more about The Pollinator Strategy for Scotland @ https://www.nature.scot/scotlands-biodiversity/helping-scotlands-pollinators

 

 

 

 

 

 

 

The value of flowering hedgerows

The loss of many farmland hedgerows shortly after the Second World War was disastrous for pollinating insects in our rural landscape. Flowering hedgerows are excellent for food, shelter and nesting sites, as well as providing a safe and convenient corridor for ease of movement.

Rural communities lamented the loss of the flowers which were a distinctive and much-loved element of fruit-bearing hedgerows.  Perhaps less obvious was that insects, birds and small mammals were denied a vital food source and home.

Today hedgerows are increasingly valued for their biodiversity benefits and the planting of new hedgerows is encouraged. But just as ‘Rome wasn’t built in a day’ neither is replacing hedgerows an overnight job.

A mixed hedgerow, with a variety of trees and shrubs, can have value through the entire life-cycle of pollinators. Blackthorn for example flowers early in the year – just in time to provide a vital food source for emerging bumblebee queens, solitary bees and honey bees. Farms with hedgerows help pollinators and enjoy many other benefits.

Hedges provide shelter for livestock (in both cold and extremely hot weather), , ,  increase the potential for carbon capture and storage in woody biomass, improve water infiltration rates to soil, reduce the potential for flooding and create wildlife corridors across farms. They provide habitat for essential wildlife, including beneficial insects and pollinators. As we increasingly look for Integrated Pest Management solutions pollinating insects provide natural pest control.

We know that pollinators, be they in a rural or an urban setting, need good food sources from early spring to autumn, in order to complete their life-cycles.

Flowering hedges that contain pussy willow, hawthorn and blackthorn are great for those insects on the wing early in the year, whilst come April and May hawthorn and wild cherry can be superb food sources for pollinators. Add to the mix dog rose, guelder rose and hazel and the potential for a hedgerow to be an all-year larder is clear.

It isn’t just the flowering of hedgerow plants that is important. At the base of hedges in amongst the tussocky grass, or vacated mammal holes, bumblebees might nest.  Bare earth under a hedge (especially if south-facing), might also provide potential nesting sites for solitary mining bees. A range of pollinators from beetles to moths and butterflies will also find those sites useful for overwintering.

In short hedges can be havens for pollinators

 

Managing hedgerows to benefit pollinators

Key to hedgerows being a bonus for pollinating insects is allowing them to flower. Many hedges only really flower on wood that is at least a couple of years old.

As well as planting or managing a range of native flowering shrubs it is important to rotate how often and when hedges are cut. This will reduce costs and be better for wildlife. Many varieties of  tree and shrub species only flower on second year growth, hawthorn and blackthorn, for example, benefit from not being cut every year.

Allowing hedgerows to flower, by moving away from the model of a tidy, short hedge, towards managing one which isn’t flailed annually is one very positive action that farmers can take. Cutting hedges is not permitted between 1 March and  31 August under cross-compliance rules. to prevent damage to  nesting birds.

Plugging gaps in hedgerows with native flowering shrubs keeps a wildlife corridor intact and leaving the occasional tree to grow above the rest of the hedge will add diversity.   A recent survey of Scottish native wild apple trees found a number associated with field margins.

Consider cultivating flower-rich strips next to hedges. Flowers such as knapweed, clovers and vetches are great for pollinators.

Aim to cut hedges in rotation, across the farm and aim for an ‘A’ shape, where the densest area is at the base. This will encourage the hedge to thicken up and provide valuable shelter beneath the hedgerow.

By managing a hedge to help pollinating insects you benefit insects, birds and mammals as well as encouraging pollinators onto your farm. Further information on all aspects of hedge management can be found on the Hedgelink website.

Making space for nature

Partnership working can provide new opportunities for learning, and can be the driver of many successful development projects.  Redrow house builders have teamed up with Bumblebee Conservation Trust (BBCT) over the last 5-years to support the conservation of pollinators in England and Wales through the development of their sites. In our blog today, Gill Perkins from BBCT tells us more about the partnership. 

Bumblebee Conservation Trust (BBCT) is a leading invertebrate charity in the UK with technical expertise and strong track record of habitat delivery, awareness raising and public engagement. BBCT represents a unique blend of scientific credibility with a friendly practical approach.

As a leading house builder Redrow prides itself on building responsibly and creating great places to live. Redrow focusses on well-designed developments that create a sense of community, with local amenities and green spaces that enhance nature and the wellbeing of the people who live there.

Our story
There is an acknowledged need for more housing in the UK and there is a widespread understanding that nature is under pressure.

The partnership between Redrow Homes and BBCT is about creating relationships that work, are sustained, and ensure Redrow’s future housing developments are better for nature, better for the health and well-being of home owners, better for pollinators, and better for future generations.

Redrow recognised that planning policies provide a good strategic vision for providing for nature through housing developments; however, these policies are often about protecting nature rather than enhancing it, and are not always translated effectively at ground level.

The partnership with BBCT ensured that pollinators specifically, and nature generally, became central to their plans.  A unique partnership with successes, challenges, learning, developing, refocusing and achievements continues.

The story starts and continues at Saxon Brook, a development in Exeter. The first of its kind; a unique and innovative housing development that has recognised the need to support our dwindling pollinators. The development boasts beautiful landscaped areas designed to encourage pollinators and other wildlife at the same time as providing colourful, beautiful and inspiring spaces for residents to enjoy. (200)

Urban spaces and gardens are becoming increasingly important for the UK’s declining population of pollinators and have the potential to provide crucial food and nest sites for bumblebees and other insects.  Working together to create bee-friendly housing developments and encouraging new home-owners to do the same in their new gardens, the two organisations have been able to achieve several key objectives that couldn’t have been realised alone.

Together we aim to change the way people think about their gardens, the area they live in and the community they are part of.  Providing an environment that is inspiring and educational for the community could be the most important application of urban ecology, as a means of promoting effective conservation of native species.

Redrow and BBCT worked together on:

Design

• Developing a joint understanding the journey of a development and the points at which BBCT could enhance the development in favour of pollinators.

Engagement

• Engaging with children on sites, planting bulbs, developing inspiring, educational stories and resources.

Maintenance & Legacy

• Training and engagement with landscaping and maintenance contractors to ensure the landscaping is managed appropriately and continues to flourish and support bumblebees in the future.

The future
The work continues with the development of a Biodiversity Net Gain strategy and a further 4 development sites for pollinators.

Together we are buzzing.

All photos provided by BBCT

Aggregations, not aggressors

There was a rather alarming pollinator story in our local newspaper recently, writes Athayde Tonhasca. A concerned reader had submitted a video showing several solitary bees writhing on the ground, clearly in their death throes. The article speculated that the bees could have been poisoned by an insecticide.

 

Healthy chocolate mining bees.

If that was indeed the case, the perpetrator could have been concerned about the risks posed by the bees. However, there was no reason to worry. The bee species in question, the chocolate mining bee, is a harmless solitary bee.

Solitary bees are docile and never go out of their way to attack people or animals. Only the female bee has a sting, and she will only try to use it if handled roughly. However, the sting usually is too weak to penetrate human skin.

Although solitary bees build their nest individually, some species nest near each other, giving the impression that they form a colony. These groups of solitary bee nests are called aggregations, which may comprise hundreds of nests in one area. Perhaps it is this which worries some people.

A male red mason bee.   ©Lorne Gill/SNH

Beekeepers occasionally are called out to investigate ‘swarms’, only to find what they are facing the comings and goings of solitary bees such as the red mason bees or mining bees, which nest in the spaces between slates, air bricks and walls.

Solitary bees do not produce honey or wax, but they but they are excellent pollinators of fruit crops and wild flowers. They provide much needed diversity in agricultural pollination, and some species are being increasingly reared for use in crop production.

There are often questions about bees flying about at this time of year, especially solitary bees.  The main message from these questions is:

leave them alone, they are harmless, will not sting, they are great pollinators, and enjoy them.

Red mason bee on tree trunk

Promoting pollination with bee houses

Besides the familiar bumble bees and honey bees, which live in colonies, there are approximately 250 species of solitary bees in the UK. They are called ‘solitary’ because each bee builds individual nests for their larvae, although some may do so communally.  In our blog today, Athayde Tonhasca looks at the ‘ins and outs’ of bee houses.

 

Most solitary bees nest in the ground. But some bees, and some wasps as well, build their nests in naturally-occurring cavities, from cracks in stones to hollow stems of dead plants or holes in wood made by boring insects. These cavity-nesting bees and wasps readily occupy artificial nests made of drilled wooden blocks, paper tubes, or bundles of reed or bamboo stems.

Once a bee or wasp occupies a cavity, it begins constructing a series of compartments (brood cells), each provisioned with pollen and nectar (in the case of bees) or paralyzed insects (wasps) as food for their offspring. When the cells are finished, the nest entrance is sealed with a plug made of mud or leaves, depending on the species. The eggs soon hatch and the larvae develop by eating the pollen and nectar mixture (bees) or prey (wasps). The larvae pupate, and after a period of dormancy, adults emerge next year to start the cycle over again.

The brooding cells from a red mason bee nest. Each cell contains pollen-nectar provisions and an egg. Males bees emerge first, thefore their eggs are laid last, closer to the nest entrance.

A number of cavity-nesting species are common in gardens, and they are useful as pollinators of fruit crops and wild flowers (bees), or pest control agents (wasps).

Gardeners can encourage cavity-nesting bees and wasps by installing bee houses. However, occupation is not guaranteed: it will only happen for species already occurring naturally in the area. If not, even the nicest bee house will remain empty. Retailers usually do not inform the buyers about this detail.

How to use a bee house

There are several types of bee houses for sale, some of them quite expensive. However, many are inadequate and will not be occupied. Even worse, they may be harmful to bees. The Pollinator Garden website and the Xerxes Society provide detailed information of how to choose or build bee houses, and how to maintain them.

These are the main requirements and aspects to avoid:

• Do not use bee houses built with plastic or glass components. These materials trap moisture, which promotes mould and diseases.
• Keep it small: large structures made of stone, tiles, logs, etc. (known as bug hotels) encourage unnaturally high concentration of bees, increasing the chance of parasites finding them. Bug houses are difficult to clean and therefore prone to harbour diseases, and some materials such as pinecones and straw are hiding places for mites that feed on bees’ pollen stores.
• In Scotland, the red mason bee (Osmia bicornis) is the most likely occupier of bee houses. This bee is active from late March to early June, peaking in May, during mass-flowering of fruit trees such as apple and pear. The red mason is spreading rapidly through Scotland. For this species, the internal diameter of tubes or holes should be within 4 to 10 mm, ideally 8 mm, with a length of at least 15 cm.
• The house must be positioned in full sun, facing southeast or south. This is important; bees rely on the sun’s heat to warm up and become active.
• Place the house at least a metre off the ground. There must be no vegetation obscuring its entrance. Fix it securely so it does not swing or sway in the wind, so you should not hang it from a branch. Face the house’s opening at a slightly downward angle to help keep it dry.

• Wind-blown rain can wet the walls of the house’s cells, exposing the young bees to diseases. Thus a bee house should have an overhanging roof to keep it dry. Few commercial products meet this requirement.
• Woodpeckers, tits and other birds may pull out tubes in search of bee larvae. If that happens, fix a piece of chicken wire across the front of the bee house.
• An occupied bee house can be moved somewhere cold, dry and free from mice and other predators at the onset of autumn or winter. An unheated shed, porch, or garage will do, as long as it is cold and dry throughout the winter. The house can be put back in March.
• Replace the house every year to avoid build-up of mould, mites and parasites.
• Finally, do not buy bees. Bees introduced to a site may disrupt the ecology of local pollinators, and releasing them in the wild may be illegal.

Other species that may occupy bee houses in Scotland are :-

• Blue mason bee (Osmia caerulescens). A smaller and less common mason bee. The females sometimes have a shiny, slightly blue body, hence its common name; the males tend to have a greener shade. They can be seen from April to September. The blue mason is widespread though southern Britain, with records extending to central Scotland.
• Patchwork leaf-cutter bee (Megachile centuncularis). Leaf-cutter bees look like honey bees, but the underside of their abdomens is orange. They are well known for their habit of cutting neat, rounded circles out of plant leaves which they use to build nest cells and seal their entrance. They are easy to distinguish from other solitary bees, as they hold their wings to the side of their bodies, unlike most bees that hold them folded over the abdomen.
• Mason wasp (Ancistrocerus parietinus). This mason wasp preys on moth and beetle larvae. It can be seen from summer to autumn. Wasps paralyse their prey rather than kill them, so that they will not rot before the larvae eat them. Many people are wary of wasps, but these insects help control some pests such as leaf-rolling caterpillars, leaf beetles and weevils.
• Mournful wasp (Pemphredon lugubris). This entirely black wasp is predatory on aphids. Adults feed on nectar and pollen.
• European potter wasp (Ancistrocerus gazella). This wasp preys almost exclusively on caterpillars. Adults feed on nectar and aphid honeydew. They are often found foraging for nectar on gardens, and searching small cracks or holes in walls in which they nest.

 

Bee houses may attract unwanted guests as well (that is, from the bee’s perspective). Ruby-tailed wasps such as Chrysis ignita and cuckoo wasps like Pseudomalus auratus are mostly parasitoids* or cleptoparasites** of other insects, generally other solitary wasps and bees. These tiny and colourful wasps do not occupy bee houses, but rather patrol their surroundings in search of hosts. Some of these wasps are rare and endangered.

 

Notes:                

* Insect parasitoids have an immature life stage that develops inside a host, ultimately killing it.

** Cleptoparasitism (meaning “parasitism by theft”) is a form of feeding in which one animal takes food from another that has caught or collected it.