Posts Tagged ‘Bee decline’

The great British public has helped scientists uncover what looks like a substantial decline in one of the UK’s most common bumblebees over the last 20 years.

By gathering valuable information about the insects, citizen scientists from across Britain have shown that the common carder-bee made up less than 10 per cent of bumblebee colonies from 2007 to 2009.

Just 20 years previously, they made up a whopping 21 per cent. [Read full article]

From Planet Earth Online

Bumblebee Conservation Trust


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Bumblebees, solitary bees and other wild pollinating insects are much more important for pollinating UK crops than previously thought, say researchers.

They found that honeybee populations have nose-dived so dramatically in recent years that they can only do half as much pollination as they did in the early 1980s.

Where honeybees used to provide around 70 per cent of the UK’s pollination needs they now only pollinate a third. At worst, that figure could well be more like 10 to 15 per cent.

Paradoxically over the last 20 years, the proportion of UK crops that rely on insects for pollination has risen from just under 8 per cent in the early 1980s to 20 per cent in 2007. And over the same period, yields of insect-pollinated crops, which include oil seed rape and field bean, have gone up by 54 per cent.

This means that honeybees can’t be solely responsible, or aren’t the only important pollinator.

So if honeybees aren’t pollinating the crops, what is? The researchers think that other important pollinating insects, such as bumblebees, hoverflies and solitary bees must be making up the shortfall.

‘Our finding suggests that wild insect pollinators make a much bigger contribution to UK crop pollination than previously thought,’ says Tom Breeze from the University of Reading, lead author of the study.

[Read full article]

Planet Earth Online

Research paper: T.D. Breeze, A.P. Bailey, K.G. Balcombe and S.G. Potts, Pollination services in the UK: How important are honeybees?, Agriculture, Ecosystems & Environment, published online 20 May 2011, doi:10.1016/j.agee.2011.03.020

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Avaaz is a 6.5-million-person global campaign network that works to ensure that the views and values of the world’s people shape global decision-making.

Yesterday they launched a campaign to urge the US and EU to suspend neonicotinoid pesticides. The full text of their campaign publicity can be read here.

BBCT share concerns about growing evidence suggesting that some pesticides, including neonicotinoids, are harmful to bees.

However, there are some statements in the Avaaz summary which, based on BBCT’s understanding of the scientific evidence, are not well supported. This weakens their position and threatens to make hard-won signatures less valuable. Furthermore, they make a strong case for pesticides being the root cause of global bee declines. In some instances pesticides may be seriously affecting honeybees, but it is BBCT’s view that many of our wild bee species have declined primarily due to habitat loss and other factors, besides pesticide use. With honeybees the situation is also more complicated than the Avaaz literature implies. Disease has a significant role in ongoing declines.

BBCT value the efforts of Avaaz in raising awareness of important issues and galvanising mass support and peaceful protest. However, in this instance the arguments are oversimplified and at times incorrect. Calling for a ban on neonicotinoids as a precaution until thorough independent research confirms their safety seems prudent and has our support. However, the campaign materials risk polarising a complex issue and undermining efforts to tackle global bee declines from all necessary angles.

Points of clarification:

Only one of the UK’s ~250 species of bee makes honey that is harvested commercially by man. Globally there are ~7 species of honeybee and ~20,000 known species of bee.

90% of the agricultural and horticultural crop species that we grow are at least partially pollinated by bees (all bee species). Pollination is either essential for any yield, or increases yield size or quality. It is estimated that bee-pollinated foods comprise around 1/3 of our diet by volume.

Although many scientific studies suggest reason for concern, there are other scientific studies that suggest these chemicals may present a low risk. To date they have not been banned in the UK on the basis that the science isn’t clear. Pesticides, sadly, seem to work on the basis of ‘innocent until proven guilty’. Further independent research will be invaluable. BBCT support the view that a precautionary ban would be wise.

BBCT are not aware of scientific evidence which demonstrates that bee populations soared in four European countries as a result of the banning of certain chemicals.

BBCT agree that a ban on neonicotinoids would probably make a significant difference in some instances to bee populations in some areas of intensive arable agriculture, where flowering crops are common. However, sadly this would not ‘save our bees’ because the root cause of most wild bee declines is thought to be the drastic loss of flower-rich grasslands and other habitats which healthy bee populations depend on. The issues for honeybees are also complex, and better understanding, treatment and control of diseases will be important.

For populations of wild bees at least, sustainable populations require an integrated approach which combines a ban on the most harmful pesticides and a sympathetic approach to farming which supports and encourages pollinators. To bring about this it is essential to gain wider recognition of the ecosystem services that bees provide, backed up by policy-level support.

Wild bee populations in grazed or mixed-farming areas need supporting through a return to species-rich hay meadows instead of silage monocultures and clover ley crops instead of widespread fertiliser use (97% of lowland species-rich meadows have been lost since WWII). In arable areas, farms should be encouraged to manage low productivity areas (margins and corners) as flower-rich habitats. There is scientific evidence showing that this management causes a large increase in foraging bee numbers, although the evidence for population-level increases is harder to gather and hence less robust.

We believe that the figures for the economic importance of pollination in the Avaaz literature are incorrect. Gallai et al (2009) estimated that the total economic value of pollination to the world agricultural output amounted to €152.9 billion, which represented 9.5% of the value of the world agricultural production used for human food in 2005. They stress that their valuation demonstrates the economic importance of insect pollinators but cannot be considered as a scenario since it does not take into account the strategic responses of the markets. In the EU25 in 2005 the insect pollination economic value was estimated at €14.2 billion. In the UK, studies are somewhat out of date, but insect pollination has previously been valued at £440 million.

In summary, BBCT agree that it is worthwhile to make voices heard, but in order to be taken seriously by policy makers and scientists it is essential that campaigns are based on the available scientific evidence. Inaccuracies are likely to weaken the impact. Further, by simplifying the issue and ignoring the importance of other factors in global bee declines the campaign risks undermining ongoing conservation efforts. Studies suggest that the causes of bee declines differ between species and include factors such as disease, habitat loss, pesticides, inbreeding, climate change and others.

BBCT have contacted Avaaz and offered to help them reach a more robust campaign stance. To date we have not heard back from them.

From the Bumblebee Conservation Trust

[Further info and related news on the BBCT site HERE]

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Disease and inbreeding might have caused US bumblebee decline over the past few decades say scientists

The abundance of four common species of bumblebees in the US has dropped by 96% in just the past few decades, according to the most comprehensive national census of the insects. Scientists said the alarming decline, which
could have devastating implications for the pollination of both wild
and farmed plants, was likely to be a result of disease and low
genetic diversity in bee populations.

Bumblebees are important pollinators of wild plants and agricultural crops around the world including tomatoes and berries thanks to their large body size, long tongues, and high-frequency buzzing, which helps release pollen from flowers.

Bees in general pollinate some 90% of the world’s commercial plants, including most fruits, vegetables and nuts. Coffee, soya beans and cotton are all dependent on pollination by bees to increase yields. It is the start of a food chain that also sustains wild birds and animals.

But the insects, along with other crucial pollinators such as moths and hoverflies, have been in serious decline around the world since the last few decades of the 20th century. It is unclear why, but scientists think it is from a combination of new diseases, changing habitats around cities, and increasing use of pesticides.

Sydney Cameron, an entomologist at the University of Illinois, led a team on a three-year study of the changing distribution, genetic diversity and pathogens in eight species of bumblebees in the US.

By comparing her results with those in museum records of bee populations, she showed that the relative abundance of four of the sampled species (Bombus occidentalis, B. pensylvanicus, B. affinis and B. terricola) had declined by up to 96% and that their geographic ranges had contracted by 23% to 87%, some within just the past two decades.

[Read full article]


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Government and retailers are under pressure to impose a ban on sale of pesticides linked to bee population decline following new research which groups call a ‘growing body of evidence’

Environmental groups including the Soil Association and Buglife are making a renewed call for an end to the use of neonicotinoid pesticides, which are among the most commonly used pesticides worldwide, after a new study linked them to a decline in bee in bee populations.
The study, published in the journal Toxicology, says the effects on bees of two particular neonicotinoid pesticides, known as imidacloprid and thiacloprid, have previously been underestimated and may explain the decline in bee populations.

It says even low concentrations of the pesticides may be more deadly then previously thought due to their high persistence in soil and water, supporting claims for the role that pesticides may play in bee deaths.
‘The acceptable limits are based mainly on short-term tests. If long-term studies were to be carried out, far lower concentrations may turn out to be hazardous. This explains why minute quantities of imidacloprid may induce bee decline in the long run,’ says study author Dr. Henk Tennekes.

Calls for a ban
Buglife campaigner Vicky Kindemba has welcomed the new research, saying it adds support to calls for a suspension in the use of the pesticides in the UK.
‘This new information adds to the growing body of evidence that neonicotinoid pesticides are very harmful and even at extremely low levels in our environment they could still negatively impact on UK wildlife including pollinators, soil organisms and aquatic invertebrates,’ Kindemba said.
The Soil Association said other products containing the pesticides  should also be withdrawn from general sale in UK supermarkets, hardware stores and garden centres.
‘If the honeybee disappeared off the surface of the globe forever we’d be facing up to an unimaginable food crisis,’ said a spokesperson. ‘This latest research only adds to the evidence that is already strong enough to justify an immediate ban on neonicotinoids today.’
The campaign group has written to the chief executives of B&Q, Wilkinson’s and Wyevale asking them to withdraw any products containing neonicotinoid pesticides from their store.

Government disregards warning
Responding to the new study, Defra said the UK would not be following some other EU countries in restricting the use of neonicotinoids.
‘This research highlights a need for more data on long-term risks to bee health. We have already been considering this and pesticide companies will soon need to provide this data under new EU rules.
‘We will keep this area under review and will not hesitate to act if there is any evidence of an unacceptable risk to bees,’ said a spokesperson.

Useful links

Full Study: The significance of the Druckrey–Küpfmüller equation for risk assessment — the toxicity of neonicotinoid insecticides to arthropods is reinforced by exposure time

From the Guardian

Also covered in the Ecologist

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The decline of honeybees seen in many countries may be caused by reduced plant diversity, research suggests.

Bees fed pollen from a range of plants showed signs of having a healthier immune system than those eating pollen from a single type, scientists found.

Writing in the journal Biology Letters, the French team says that bees need a fully functional immune system in order to sterilise food for the colony.

Other research has shown that bees and wild flowers are declining in step.

Two years ago, scientists in the UK and The Netherlands reported that the diversity of bees and other insects was falling alongside the diversity of plants they fed on and pollinated.

[Read full article]

BBC News

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The economic crisis has contributed to a glut of bees in California. That raises questions about whether a supposed global pollination crisis is real.

AT THE end of February, the orchards of California’s Central Valley are dusted with pink and white blossom, as millions of almond trees make their annual bid for reproduction. The delicate flowers attract pollinators, mostly honeybees, to visit and collect nectar and pollen. By offering fly-through hospitality, the trees win the prize of a brush with a pollen-covered bee and the chance of cross-pollination with another tree. In recent years, however, there has been alarm over possible shortages of honeybees and scary stories of beekeepers finding that 30-50% of their charges have vanished over the winter. It is called colony collapse disorder (CCD), and its cause remains a mystery.

Add to this worries about long-term falls in the populations of other pollinators, such as butterflies and bats, and the result is a growing impression of a threat to nature’s ability to supply enough nectar-loving animals to service mankind’s crops. This year, however, the story has developed a twist. In California the shortage of bees has been replaced by a glut. [Read full article]

The Economist

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