This article is not marine based, but it is a current issue that affects us all and is definitely worth a post. Einstein once said, "If the bee disappears from the surface of the earth, man would have no more than four years to live." The famed physicist never actually said it. But this shouldn’t discourage the fact that bees are a vitally important part of earth’s systems – as pollinators, they are linked to the survival of almost all plant species, but also the crops we depend on as humans. They perform an ecosystem service worth billions of dollars, can you imagine if we had to pollinate millions of acres of crop lands by hand if bees disappeared?
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| Einstein and his bee (Image from www.insectnewsnetwork.com) |
Our
indispensible bee heroes are currently however facing a crisis – whole colonies
are dying. In 2008 over 11 500 colonies in Bavaria and Germany were
affected by a catastrophic die-off. Honey bees were simply not leaving the
hives. The investigation revealed that the incorrect application of a pesticide
(of the neonicotinoid family)
had been spewing toxic chemicals into the air, killing the bees. The
European Union wants to ban three of the most common neonicotinoid pesticides
that threaten honey bees and other pollinators, and this may happen by the end
of 2013. This is all very well and good, but it is also imperative to fully
examine the evidence before such a big decision is made. There is as yet no
full agreement between scientists as to whether pollinators are exposed to
enough pesticides on a under normal conditions to have such a catastrophic
effect on their colonies. This is because it is extremely difficult to do
rigorous scientifically sound field trials. Pesticide companies obviously say
that their product is safe as long as it is used correctly, but the real
evidence must come from studies that are not funded by these companies. While we
depend on pesticides to produce enough food for our constantly growing
population, there is some evidence that the use of neonicotinoid pesticides
does not improve crop yield that significantly. So what are we to do?
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| A honey bee superhero (Image from en.wikipedia.org) |
The US based Environmental Protection Agency
(EPA) first approved the use of neonicotinoid pesticides in 1994, and
they have since become the most widespread insecticide in the world, used in
140 crops and in numerous garden and horticultural products. Most neonicotinoid pesticides work on the more
environmentally friendly principle (rather than ‘spraying’ huge areas of crops)
of coating the seeds before planting to protect them from soil pests. As the
seed grows, it is able to incorporate the insecticide properties from the
coating and the young plant is protected as well. This means that a lot less
pesticide is used. However, concerns about the affects of these pesticides on
other species like birds, earthworms and especially bees are growing – pollinators
can be exposed to toxic chemicals through the nectar, pollen or from the seeds
themselves. The toxic substances ingested are then invariably fed to the young
in the hive, affecting the whole colony.
There is no doubt that high levels of neonicotinoid
pesticides do what they are designed to do –they kill insects, even the good,
useful ones like bees. However, a multitude of studies in the lab have shown
that even low doses can cause damage, influencing the behaviour of the bees.
These effects include changes in memory and learning, often leading to bees
losing their way or never leaving the hive in the first place. It is difficult
however to apply what has been learned about the effects on individual honey bees
to the hive as a whole – the colony can carry on even if a lot of bees are
lost.
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| A honey bee fitted with a tiny radio chip to allow researchers to study how movement patterns change after exposure to the pesticides (Image from www.sciencemag.org) |
A 2012
study by Goulson and colleagues focused on the effects of neonicotinoid pesticides on
bumblebees, because their smaller colony sizes may make them more vulnerable. They
found that the colonies exposed to the pesticides had a significantly reduced
growth rate, and that fewer new queens were produced (85% fewer in fact)
compared to colonies that were not exposed. They concluded that the prolific usage
of neonicotinoid pesticides in the developed world may be having a hugely
negative impact on wild bumblebee populations, and thus other pollinators. A number of other studies have been
undertaken, some showing negative effects and some showing no effects at all on
colonies after neonicotinoid pesticide
exposure. A huge amount of money is going into finding the answer, with one current study funded $950 000 by Bayer
CropScience, a manufacturer of pesticides. It seems like the problem is being
faced head-on by the companies, they are putting the money out there to find an
answer and thus, a solution. Because the survival of bees is everyone’s
business.
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| A bumblebee, as studies by Goulson et al (2012) (Image from www.gizmag.com) |
Pollinators are exposed to a cocktail
of chemicals, not just neonicotinoid pesticides. For instance, pyrethroids
may pose an even greater threat to bees (EPA and USDA, 2013). Commercial hives, used to either produce honey
or moved around the country to pollinate various crops can contain as many as
30 chemicals (Frazier etal, 2008).
The honey combs themselves accumulate pesticides, making the situation worse
over time. The dilemma is that pesticides found in the highest concentrations
are used to control a parasitic mite (Varroa
destructor) which may be the biggest threat to honey bee colonies (PingChen and Siede, 2007).
Without the insecticides, the mites destroy the colony.
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| A honey bee with a mite (Varroa destructor) visible on the side of its body (Image from www.alexanderwild.com) |
Despite the uncertainties, the EU is moving quickly to
tighten regulations to protect the honey bee after the European Food Safety
Authority (EFSA) released a report clearly stating that neonicotinoid
pesticides posed “high acute risks” to pollinators. The European Commission
decreed that as of December, farmers won’t be able to plant seeds treated with three
neonicotinoid pesticides, nor spray the chemicals on crops preferred by
bees. Scientists in industry and the academic world are currently working to
make neonicotinoid covered seeds safer by reducing the
amount of toxic dust released when the seeds are planted. And breakthroughs are
being made. Researchers also continue to investigate how these chemicals affect
the wider ecosystem. At least these pesticides are getting the widespread scrutiny
they deserve - the world as we know it will cease to exist without bees.
