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World’s mostly used insecticide proven to damage bees’ brains

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Researchers have found evidence that the
most frequently used insecticide on crops such as corn, canola, cotton, and soybeans
is creating problems to the brains of bumblebees, and causing poor performance
in their colonies.
 

The reasons behind the global decline of bees and other insect
pollinators have been as mysterious as they’ve been controversial, but
now we have the first evidence to suggest that commercially available
insecticides are the reason behind it.
Neonicotinoids – new class of insecticide, developed by
Shell and Bayor around 20 to 30 years ago, that are now considered the most widely used class of insecticides in the world. According to Elizabeth Grossman,
in the US, neonicotinoids are used on about 95 percent of corn and
canola crops, and are the most commonly used insecticide on cotton,
sorghum, and sugar beets. The majority of fruit and vegetable crops in the US, including
apples, cherries, peaches, oranges, berries, leafy greens, tomatoes, and
potatoes, are also treated with this insecticide. 
But the widespread use of neonicotinoids, despite serious questions
regarding their safety around bumblebees and other insect pollinators,
has not gone unnoticed. In 2013, following the results of a year-long
study concluding that continued use would have “high acute risks” for bees, the European Commission placed a two-year moratorium
on the use of neonicotinoid chemicals on all plants that attract bees.
And in Australia, a definitive report on neonicotinoids and bees, led by
Robert Manning from the Western Australian Department of Agriculture
and Food, will be released in the next few months, the results of which are expected to influence local policies regarding neonicotinoid use.
Now, a team from the Universities of St Andrews and Dundee in Scotland has published a study in the Journal of the Federation of American Societies for Experimental Biology
that shows for the first time that even the small amounts of
neonicotinoid insecticide found in nectar and pollen is enough to affect
the brain activity of the bumblebees that consume it. 
This small amount, the team says,
is about 2.5 parts per billion – so around 1 teaspoon in an Olympic
swimming pool. There has been much debate over whether this amount could
actually be having any effect on the bees at all, so the researchers
fed it to a number of bumblebees to see what happened. And because the
chemical is designed to target the brains of insects, they tested its
accumulation in the bees’ brains.
The Scientists have found that some
of the neonicotinoid chemicals would very quickly shut down mitochondria
in the brain cells of the bees, which affects the brain’s ability to
produce energy. The chemicals also messed with the ability of the
different regions to communicate with each other, which affected the
bees’ ability to learn crucial skills, such as remembering how to get
back to the colony, and connecting the scent of a flower to the
anticipation of a food reward.
Having tested the amount in individual bees, they then tested whole
colonies, contaminating their sugar water with neonicotinoids. The
colonies ended up forming smaller, and less robust nests than they
normally would, which also contained less bees. The team concluded that
even super-low levels of neonicotinoids saw an estimated 55 percent
reduction in live bee numbers, a 71 percent reduction in healthy brood
cells, and a 57 percent reduction in the total bee mass of a nest.
“Our
research demonstrates beyond doubt that the level of neonicotinoids
generally accepted as the average level present in the wild causes brain
dysfunction and colonies to perform poorly when consumed by
bumblebees,” one of the team, Chris Connolly from the Division of Neuroscience at Dundee’s School of Medicine.
“In fact, our research showed that the ability to perturb brain cells
can be found at one-fifth to one-tenth of the levels that people think
are present in the wild.”
Connolly adds that the results are not so surprising – these
insecticides are designed to affect the brains of insects, so of course
they’d mess with non-pest species too – but neonicotinoid use has been
allowed because the chemicals don’t actually kill bees. 
He also said, “This is not
proof that neonicotinoids are solely responsible for the decline in
insect pollinators, but a clear linear relationship is now established.
We can now be confident that at these levels, neonicotinoids disrupt
brain function, bee learning and the ability to forage for food and so
limit colony growth.”

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One
of the reasons neonicotinoid use has been allowed to continue for so
long, despite serious concerns regarding its effects on non-pest
pollinators, is the difficulty in transitioning the global agricultural
industry from its most commonly used insecticide to another viable
alternative. Neonicotinoid is very good at what it does, otherwise
farmers wouldn’t be using it, so they expect the scientific evidence as
to why they shouldn’t, to be rock-solid. And small sample sizes are one
of the main gripes.
“Field studies of the effects of neonicotinoids on bees are plagued
by small sample sizes and ‘pseudo-replication’, in which data are
analysed assuming that each colony is independent, even though multiple
colonies are housed within a single box, and so experience a common
environment,” one of the team, Steve Buckland, professor of statistics
at the University of St Andrews said.
Buckland explains:
“Small
sample size in field trials has been used as an excuse to not carry out
formal analysis, and to draw a conclusion that there is no observable
effect of neonicotinoids from visual inspection of the data. Despite the
limited true replication, we found very strong evidence that low levels
of neonicotinoids have adverse effects on bumblebee colonies, with an
estimated 55 percent reduction in live bee numbers, 71 percent reduction
in healthy brood cells, and 57 percent reduction in the total bee mass
of a nest.”
According to Grossman from Yale Environment 360, over
the past decade, beekeepers around the world – primarily in the US and
in Europe – have been reporting a loss of at least 30 percent of their
hives each year, and in 2013, that number hit 40 to 50 percent for many
American beekeepers. And we’re talking about the insects that make an
estimated $215 billion contribution to the global economy, while also
supporting a good deal of the world’s crop production.
So, what’s the solution? It may not be necessary to ban the use of neonicotinoids altogether, says Connolly,
but instead we should be looking at stricter regulations regarding its
use. “It may be possible to help bees if more food (bee-friendly plants)
were available to bees in the countryside and in our gardens,” he said.
“We suggest that the neonicotinoids are no longer used on any
bee-friendly garden plants, or on land that is, or will be, used by
crops visited by bees or other insect pollinators.”

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