Weeds TWICE as likely to attract bees than wildflowers, study finds

Why gardeners should think twice before killing their weeds: ‘Dangerous’ plants including ragwort, thistles and docks are TWICE as likely to attract bees than wildflowers, study finds

  • Researchers compared biodiversity of weeds with DEFRA-recommended plants
  • Ragwort, thistles and docks were found to attract twice as many bees
  • Despite their benefit to pollinating insects, around £10 million is spent every year controlling injurious weeds

Weeds like ragwort, thistles and docks can be a nightmare for keen gardeners, but a new study may make you think twice about getting rid of them.

Researchers from the University of Sussex have revealed how these ‘dangerous’ plants are twice as likely to attract bees than wildflowers.

Francis Ratnieks, an author of the study, said: ‘Many common native plant species valuable to wildlife conservation are, unfortunately, underappreciated.

‘Here we show the importance of ragwort and thistles to flower-visiting insects.’ 

Weeds like ragwort, thistles and docks can be a nightmare for keen gardeners, but a new study may make you think twice about getting rid of them. Pictured: a honey been on the flowers of common ragwort

Bee populations are declining 

Declines in recent years to bee numbers caused global concern due to the insects’ critical role as a major pollinator.

Bee health has been closely watched as nutritional sources available to honey bees have declined and contamination from pesticides has increased.

In animal model studies, researchers found that combined exposure to pesticide and poor nutrition decreased bee health.

Bees use sugar to fuel flights and work inside the nest, but pesticides decrease their hemolymph (‘bee blood’) sugar levels and therefore cut their energy stores.

When pesticides are combined with limited food supplies, bees lack the energy to function, causing survival rates to plummet.

In the study, the researchers compared the biodiversity value of plants classified as ‘injurious weeds’, with DEFRA-recommended plants such as red clover and wild marjoram.

The team conducted a field study in East Sussex, where they studied three types of weeds – ragwort, thistles and docks – as well as other wildflowers.

Based on the Database of Pollinator Interactions, the researchers found that four times as many pollinator species, and five times more conservation-listed species have been recorded visiting the three weeds.

Meanwhile, twice as many herbivorous insect species are associated with the weed species, according to the Database of Insects and of their Food Plants.

Dr Nicholas Balfour, an author of the study, said: ‘There now exists a substantial body of evidence which shows that weeds are a vitally important resource for pollinators.

‘The three insect-pollinated species have open flowers that allow access to a wide variety of pollinator species, and they produce, on average, four times more nectar sugar than the DEFRA recommended plant species.

‘Pollinators are crucial to maintaining global biodiversity, ecosystem resilience and agricultural output. 

‘However, there are significant concerns about pollinator declines and the long-term decline of flowers in our landscapes is considered a key factor.

‘We appreciate that agricultural weeds can cause yield losses in arable and pastureland. 

‘However, we’ve shown that they can also be of great value to both flower-visiting and herbivorous insects – and shouldn’t be underestimated when it comes to supporting our natural biodiversity.’

Despite their benefit to pollinating insects, around £10 million is spent every year controlling injurious weeds, according to a freedom of information request to public bodies.

Dr Balfour added: ‘It is alarming that the many public bodies are using tax-payers’ money and volunteers to actively remove ragwort. 

‘This plant was found to support the most conservation-listed insect species in our study.

‘The implementation of the Ragwort Control Bill probably deserves greater scrutiny, especially given that the evidence underpinning it is questionable.

‘Our results clearly show that weeds have an underappreciated value in supporting our natural biodiversity. 

‘Unfortunately, current UK agricultural policy encourages neither landsparing for, nor landsharing with, weeds.’ 

WHAT ARE THE UK’S MOST ENDANGERED PLANTS?

The Ghost Orchid was last seen in 2009 in a Herefordshire wood

1. Ghost Orchid

Status: Critically Endangered 

Best time to see: Unknown

Habitat: Beech wood

Where? Herefordshire

This orchid was thought extinct until it was spotted in Herefordshire in 2009. It usually grows underground in deep leaf litter only rarely popping its white flower above the surface to attract pollinators.

 

The Red Helleborine grows in southern England and is best seen in May, June and July

2. Red Helleborine

Status: Critically Endangered

Best time to see: May, June and July

Habitat: Dark woodland

Where? Southern England

This orchid grows a stem up to 60cm in height that can carry up to 17 flowers that are a deep shade of pink. Plantlife UK said it may have become rare due to a decline in the population of its pollinators and the right habitat for them.

 

Spreading Bellflowers are only found in 37 places in the UK

3. Spreading Bellflower

Status: Endangered

Best time to see: July to November

Habitat: Woodland

Where? Welsh borders and west Midlands

The Spreading Bellflower is only found in 37 10-km square areas in the UK, but in very small numbers. It is threatened by changes in woodland management, such as the end of coppicing and other disturbances, and an increased use of herbicides on roadsides and railway banks.

 

The Crested Cow-wheat grows in East Anglia and other parts of the UK

4. Crested Cow-wheat

Status: Endangered

Best time to see: July and August

Habitat: Rocky Hillside meadows and roadsides

Where? East Anglia and other areas

The plant grows to 15 to 40cm high and produces pink flowers with yellow lips. It grows in meadows, competing with scores of other plants to attract insects.

 

5. Cotswold Pennycress

Status: Vulnerable and Near-Threatened

Best time to see: April and May

Habitat: Farmland

Where? Cotswolds

It sprouts mainly in the Cotswolds, and can be seen growing out of hedges, walls and banks.

Ploughing, the levelling of rough land, increased use of fertilisers and herbicides and neglecting marginal land have all led to the plants gradual demise. It is often choked by thicker smothering plants.

 

The Lady Orchid, which has stunning pink flowers, grows in Kent and Oxfordshire

6. Lady Orchid

Status: Critical

Best time to see: April, May, June

Habitat: Edges of woodland and grassland

Where? Kent and Oxfordshire

This purple-coloured orchid produces large stems of 200 flowers that grow up to 80cm in height. It can be seen growing on the edges of woodland, and sometimes in open grassland.

This meadow plant has been in decline since less land was used for grazing meaning it was smothered by others

7. Meadow Clary

Status: Vulnerable/Near Threatened

Best time to see: Spring and Summer

Habitat: Grassland

Where? Oxfordshire, Chilterns and north and south Downs

This plant declined before 1950 when less land was used for grazing and it was smothered by other coarser plants. It is now found in just 21 areas in the south of England, where it was probably re-introduced through ‘wild flower seed’ mixtures.

The sun loving plant grows in open grassland, and along south-facing hedge banks and the southern edges of woodland.

 

The One-flowered Wintergreen grows in damp, shaded pine forests

8. One-flowered Wintergreen

Status: Vulnerable/ Near Threatened

Best time to see: May, June and July

Habitat: Pine forests

Where? North-east Scotland

This single-flowered plant grows in damp, shaded areas of pine forests. It is clearly visible against the dark soil and rotting pine leaves. The white flower faces downwards from the end of a tall stem, looking a bit like an umbrella

 

The Twinflower is a relic from the ice age

9. Twinflower

Status: Unknown

Best time to see: Spring and Summer

Habitat: Woodland

Where? Scotland

An arctic-alpine plant that is a relic of the ice age, It has two pink bell-like flowers on a slender stem and a thicker stem below that creeps along the ground forming small mats. The Twinflower is considered one of our smallest and most delicate native flowers.

It now grows in just 50 unrelated sites following changes in woodland management.

 

The white-flower orchid has been lost from 75 per cent of the countryside

10. Lesser Butterfly-orchid

Status: Vulnerable/Near Threatened

Best time to see: June & July

Habitat: Woodland, grassland, heathland and wetland

Where? England, Cardiganshire in Wales, and parts of Scotland and Northern Ireland

This white-flower orchid has been lost from 75 per cent of the English countryside since records began. Growing a 30cm-high stem, the plant is now scattered across open areas and those with acidic soil. The best chance of seeing it is in the Cae Blaen Dyffryn Nature Reserve, Wales, which hosts a population that can exceed 3,000 in good years.

The orchids decline may be linked to a symbiotic fungus it depends on to grow, according to Plantlife UK, which is very sensitive to fertilisers and fungicides. Their use on open grassland may have played a part in the plants march towards extinction.

 

The plant prefers Beech and Hazel woods

11. Yellow Birds-nest

Status: Unknown

Best time to see: All year

Habitat: Beech and Hazel woodland

Where? UK-wide

The whole plant is a yellow-brown colour, and tends to grow in leaf litter in shaded woodland. However, it began to decline after 1930, possibly due to changes in woodland management, overgrazing and habitat fragmentation.

Source: Plantlife UK 

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