Written by fatih al-farahat in


Colony Collapse Disorder Linked to Cumulative Pesticide Buildup





I posted on the link between recent pesticides and colony collapse disorder back in September of 2008.  It was pretty compelling then.  We lacked only the details.

 

Here is my original post:

 

http://globalwarming-arclein.blogspot.com/2008/09/colony-collapse-disorder-resolved.html

 

This article solves that minor omission and discovers the route to resolution so that perhaps we will not need to throw the baby out with the bathwater.

 

The bottom line is that Neonicotinoid based insecticides are a disaster because they accumulate in the insect’s body.  That is how its long term effect was missed in testing.  In time the insect succumbs and in the case of bees, it is likely that the queens succumb first forcing the collapse of the hive.

 

The science can not be more damning.  All prior studies are obviously flawed and need to be completely redone.  In the meantime the products have to be withdrawn.

 

Beekeepers will need to extensively monitor the local use of pesticides to establish the level of danger.  That way they can save their hives.  The good news is that been cumulative, it may be possible to accept occasional exposure from a far flung field or two.  Most hives are set to pollinate a specific crop and it is not too hard to work directly with farmers to work around the problem now we know exactly what we are up against.

 

 

Insecticide implicated in bee decline

Aug 27, 2010

Honeybees, bumblebees and many other insects are being slowly poisoned to death by persistent insecticides used to protect agricultural crops. Small doses of the toxic chemicals accumulate over time, meaning that there is no safe level of exposure. That’s the conclusion from recent research looking at the long-term effects of a commonly used class of insecticides.

As they buzz from flower to flower, bees, moths and hoverflies carry out a vital job. Around one third of agricultural crops are pollinated by these busy insects, a service that is worth £440 m a year to the UK economy alone.

But in recent years these valuable pollinators have been struggling, with populations plummeting worldwide. Honeybees in particular have been suffering, with colony collapse disorder (CCD) – a phenomenon where the bees desert the hive – becoming more common in Europe and North America.

Controversy has swirled around the issue, and everything from mobile phones to GM crops have been blamed. Now new studies indicate that insecticides are playing a significant role.

The most recent studies have exposed a variety of insects to varying doses of neonicotinoid insecticides over long time periods – 12 months or more. Neonicotinoid insecticides are widely used worldwide; they work by acting on the central nervous system of the insect. The chemicals have little affinity for vertebrate nervous systems, so they are much less toxic to mammals and birds.

The researchers found that the total dose of insecticide required to kill the insect was smaller if administered over a longer time period (Ecotoxicology (2009) 18:343–354). In the case of honeybees, up to 6000 times less insecticide was required to kill them if it was administered in multiple tiny doses over a long time period.

According to Henk Tennekes, a researcher at Experimental Toxicology Services (ETS) in the Netherlands, these findings make perfect sense. “Start by considering a high exposure level,” he said. “It may cause an early effect, such as cancer or mortality. At a much lower exposure level you may get a late effect. However, as it turns out, in the latter case you need much less of the stuff (in total) to produce the effect.” Tennekes describes the findings in a forthcoming paper inToxicology.


So how do these insecticides achieve such a powerful long-term effect? The answer lies in the way that they work. Neonicotinoids bind irreversibly to receptors in the central nervous system of insects. “An insect has a limited amount of such receptors,” explained Jeroen van der Sluijs, a scientist at Utrecht University in the Netherlands, who has also worked on the problem. “The damage is cumulative: with every exposure more receptors are blocked until the damage is so big that the insect cannot function anymore and dies.”

Even small doses over a short time period can cause serious problems. At low doses insects have been observed to become disorientated and less co-ordinated in their movements, making them easier prey for predators. Sub-lethal effects such as this weaken the insect; they particularly jeopardize social insects, which depend on the entire colony being healthy for survival.

Right now it still isn’t possible to say if neonicotinoids are the sole cause of CCD in honeybees, but it seems likely that they play a significant role. “It explains the rapid increase in CCD since 2004, which coincides with the rapid growth in worldwide use of neonicotinoids – the most widely used class of insecticides,” said van der Sluijs.

Currently the insecticides are commonly used to coat seeds, regardless of whether there are many insect pests or not. They leach easily into soil and water and are taken up readily by plants, making the entire plant toxic to insects. And as the new research shows, even at very low levels they have the potential to cause huge damage to insect populations. “I think these insecticides need to be replaced by less long-lived alternatives that are less toxic to honeybees and less prone to leaching,” said Tennekes.

About the author

 

Kate Ravilious is a contributing editor to environmentalresearchweb.