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Who's Responsible For The Long-Term Decline Of Wild Bee Species?

First Posted: Aug 17, 2016 04:10 AM EDT

A new study claimed that the continuous decline in the number of wild bees across England has been linked to the use of insecticides known as neonicotinoid on oilseed rape crops.

New Scientist has reported that before seeds are planted, neonicotinoids are applied to them which can later on be transported to every single tissue of a certain crop. This means that those who ingest the nectar of these seeds will also ingest the insecticides.

There have already been several documents showing the different effects of this particular pesticide on bees. However, there were not enough evidence to make the connection between the pesticides and the long-term losses of wild bee species. Ben Woodcock at the Centre for Ecology and Hydrology (CEH) in Oxfordshire, UK, and his colleagues have analyzed data on 62 species if bees  collected by volunteers from more than 31,818 surveys across more than 4000 square kilometers of land.

According to Reuters, researchers looked at bee populations between the years 1994 and 2011. They found out that in England, farmers first started tainting their oilseed rape with neonicotinoids in 2002. Manufacturers rejoiced about this development as said that it is a major advance in reducing the need for spraying leaved with other insecticides. Now, around 85% of the oilseed rape crop in uses this method for pest protection in England

"Prior to this, people had an idea that something might be happening, but no-one had an idea of the scale," he told reporters. "(Our results show that) it's long-term, it's large scale, and it has many more species than we knew about before."

The current study suggests that the harmful impacts observed by scientists in the lab can be linked to a large scale population extinction of wild bees, especially those that spend longer time foraging on oilseed rape. "The negative effects that have been reported previously do scale up to long-term, large-scale multi-species impacts that are harmful," said Dr. Nick Isaac, a co-author of the new paper.

"Neonicotinoids are harmful, we can be very confident about that and our mean correlation is three times more negative for foragers than for non-foragers," he added. BBC News has also mentioned that the decline in the number of the total population by 10 percent, due to neonicotinoids, which included about 34 species of bees that forage on oilseed rape. Five of the species showed reduction of 20 percent or more, and the worst reduction discovered was by 30 percent. All in all, at least half of the total decline in the number of wild bees is related to the chemicals.

Dr. Woodcock explained that oilseed rape were beneficial for bees because it was an enormous foraging resource all across the countryside. "But this co-relation study suggests that once its treated with neonicotinoids up to 85%, then they are starting to be exposed and it's starting to have these detrimental impacts on them," he added. "What we can't say is what these detrimental impacts are but what it does suggest is you can have these population declines and they can be big - I mean 30% is a big decline." The team said this study be a great addition to the body of evidence being considered in a review of neonicotinoid risks to bees done by the European Food Standards Authority which is expected to be completed by January 2017.

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