Long horned bee Eucera longicornis

What are the causes of bee decline?

25 Jul 2017
Why are bees declining and what are the main threats to bees? Our expert guide to the threats affecting bee populations in the UK and worldwide.

Here in the UK, and globally, bees are facing many threats. These include habitat loss, climate change, toxic pesticides and disease. The interaction between these makes an unpredictable future for bees and many other pollinators. These threats have led to nearly 1 in 10 of Europe’s wild bee species facing extinction.

1. Habitat loss - less forage and shelter for bees

Changes in our land use, including insensitive urban development and intensive farming, have caused significant losses and fragmentation of pollinator-friendly habitats. This results in bees losing the diverse food sources they need for a healthy diet.

It’s vital that bees have enough flowers to forage – and safe places to use for nesting, among vegetation, the soil and hedges. But since the Second World War, we’ve lost 97% of our wildflower meadows, leaving our bees with little natural habitat.

The loss of key habitats on farmland in particular has meant that wildlife, including bees, have become more dependent on protected wildlife sites. Yet government figures show that in the UK, only 6% of habitats protected by EU laws are in '"favourable condition". 

photo of bee hives next to field of oilseed rape

a) Intensive farming

Modern intensive farming methods have resulted in the loss of traditional hay and flower meadows, hedgerows, trees and other habitats such as ponds and water meadows.

Restoring more of these natural habitats to our farmland could benefit farmers by boosting the free natural services that wildlife provides - such as pollination and natural predators to eat pests. This is one reason why Friends of the Earth is calling for a sustainable approach to farming. Such an approach relies less on artificial chemical pesticides. It places greater emphasis on wildlife-friendly farming and solutions such as integrated pest management - see our guide on how to grow oilseed rape using this approach.

b) Land use change

Intensive land use in the UK has led to the loss and fragmentation of natural habitats and the threats to many native British species including bees and other pollinating insects.

So it’s more essential than ever that new urban development such as housing avoids damage to important habitats, like the remaining wildflower meadows. What's more it must also incorporate 'green infrastructure' that can significantly benefit bees and other wildlife.

Red tailed bumblebee. Image: Rory Dimond

Local authorities have an important role to play in safeguarding native pollinators as they manage significant areas of land, including parks, allotments, roundabouts and road verges. Find out more about the role of local authorities in helping pollinators [PDF].

2. Climate change - disrupting bee behaviour

As winters become warmer and wetter, and seasons shift there are signs that some wild species may be in the wrong place at the wrong time.

Scientists are starting to detect that changes in climate may be disrupting bee nesting behaviour and their emergence after winter. Climate change may also be as affecting the timing of the flowering of plants that bees rely on for food. The Tawny mining bee has managed to adapt to changing climate conditions, by moving northwards; but it is not certain that all bee species will be equally adaptable. A warming climate could restrict the range of bumblebees since studies have shown they have difficulty moving northwards.

Apple trees, for example, could be in blossom at a different time from when the bees are active. This would mean the bees have less food, and the trees don’t get pollinated or produce fruit. As certain bee species move north, there could be only a small area of the UK where apple orchards overlap with the bees they need for pollination. This could affect many food crops in a similar way; it could also affect bees' health.

3. Pesticides including neonicotinoids - harming bee health

Even when applied correctly, pesticides can have adverse impacts on bees by reducing their breeding success and resistance to disease. Scientists have found that exposure to pesticides can impair honeybees' ability to navigate, bumblebees' ability to reproduce and solitary bees' ability to reproduce any young at all.

Pesticides are designed to kill unwanted pests, but their toxic properties and widespread use are also harming beneficial insects such as bees.

Neonicotinoids are a particularly harmful group of bee-harming pesticides. When a bee feeds on pollen or nectar containing them, their central nervous system can be affected. This affects tasks that bees depend on to survive such as feeding, homing, foraging and reproducing.

New research has also begun to show an increase in pesticides being found beyond the farms where the seeds are sown. Learn more about how neonicotinoids affect bees and the wider environment

As well as pesticides, the use of herbicides in parks, streets and on roadside verges reduces the availability of forage plants that bees and other pollinating insects seek out for food at different times of the year.

4. Pests and disease - double trouble for British bees

Bee keepers guard their honeybee colonies against a range of pests and diseases. These include the varroa mite – a tiny parasitic mite that attaches itself to a honey bee, transmits disease and saps its strength – or fungal diseases that affect the closely knit colony.

Evidence shows that some honeybee diseases can spread to wild bumblebees. It is yet unclear if they spread to solitary bees.  Managing honeybee health is one way beekeepers can protect wild bees as well as their hives.

5. Invasive species - bad news for bees?

Some species, such as Carpenter bees, that are not naturally found in the British Isles can become established here without posing any problems. Others can be disruptive - or worse  -to native species; for example the Asian Hornet, which recently arrived in the UK could devastate British bee species if they took hold and the Small hive beetle could damage Honeybee and Bumblebee colonies if it arrived here.

Find out more about how you can help the Asian Hornet Watch.

Combined effects

These individual causes are bad enough for bees, and there is evidence to show that they work in combination, weakening bees and other pollinating insects. A hungry bee exposed to pesticides and poor weather and afflicted with pests and diseases is unlikely to survive for long. However the interactions between these effects are difficult to untangle. Scientists are continuing to carry out much-needed research into the impacts of all these factors together on bee populations.

Help ban bee-harming pesticides

Further reading

Thematic Assessment of Pollinators, Pollination and Food Production

The Decline of England's Bees [PDF]

Policies for Pollinators. The Need for Government Leadership in Backing Britain's Bees [PDF]