terça-feira, 16 de agosto de 2016

Pesticides affect ‘far more species’ of bees, says study

Pesticides affect ‘far more species’ of bees, says study

UK study links population decline to increase use of neonicotinoids in oilseed rape cultivation

by: Pilita Clark, Environment Correspondent

New research suggests that a family of pesticides has cut the presence of wild bees in the English countryside by as much as 30 per cent over the past decade as the use of the chemicals in oilseed rape crops has surged.
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In defence of bees

The health of bees is not just a popular campaigning issue for environmental non-governmental organisations and wildlife enthusiasts. It is also crucial to the global food supply.

Neonicotinoids, chemically similar to nicotine, appeared to affect “far more species than we previously thought”, said study co-author Dr Nick Isaac of the UK’s Centre for Ecology and Hydrology, a research organisation.

“Neonicotinoids are harmful. We can be very confident about that.”

The findings will fuel the debate over the mysterious disappearance of bees in several countries. In the US a collapse of honeybee colonies — dubbed the “bee-pocalypse” — has raised fears of a pollination crisis.

Bees and other insects are estimated to pollinate nearly 10 per cent of the world’s food crops.

Scientists have pinpointed possible causes for the decline, including parasites, habitat loss and climate change. But some studies have suggested a link with neonicotinoids, which are made by big agrichemical companies such as Germany’s Bayer and Syngenta of Switzerland.

The EU imposed a two-year moratorium on three types of neonicotinoid in 2013, a move that Syngenta said was based on “poor science”.

Bayer has said studies in the US, Canada, Germany and elsewhere have linked poor bee health with mites and viruses, not insecticides, and that big falls in bee populations date back to the early 1900s.

The British research tries to fill gaps from earlier studies, which looked at as few as three species of commercially bred bees exposed to neonicotinoids in laboratories over a relatively brief period of time. This time scientists studied 62 species of wild bees over nearly 18 years from 1994, using data collected by volunteers in Britain’s Bees, Wasps and Ants Recording Society and other sources.

Nearly half the species studied forage on oilseed rape, a flowering plant that turns fields into a sea of bright yellow and produces an increasingly sought-after vegetable oil that is used to make salad dressing and biodiesel.

Oilseed rape, production of which has risen globally in the past 20 years, is one of the main crops treated with neonicotinoids worldwide, including in the UK after 2002.

The study, published in the Nature Communications journal on Tuesday, suggested that neonicotinoids had caused bee species that fed on oilseed rape to become 10 per cent less widespread on average, with the worst affected species declining 30 per cent.

Dr Ben Woodcock, the paper’s lead author, said the findings were important because they covered such a large number of species over a long period and were applicable globally.

“People had an idea that something might be happening, but nobody had an idea of what the scale of that impact potentially was,” he told reporters in London.

“We are seeing correlative long-term evidence that there is an impact of neonicotinoids, particularly for species that feed on oilseed rape — a negative impact.”

How the outcome of a debate on chemical use in the US and Europe could impact on the insects

The EU moratorium was imposed after scientists at the European Food Safety Authority examined the risks posed to bees. Their assessment is due to be updated by January, and the study’s authors said they hoped their research would be taken into account.

However, they declined to say if they thought the moratorium should be extended or made permanent.

“Our job is to provide the independent evidence to the policymakers,” said Richard Pywell of the Centre for Ecology and Hydrology. “It’s not our job to decide upon policy.”

The study says it may be possible to grow oilseed rape without extensive use of neonicotinoids. It points to recent UK analysis showing that the use of the pesticides does not boost farmer profits on average.

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