NBC Science News: Insecticides can weaken & kill honeybees - that's bad news

Once upon a time all honeybees had to worry about were silly old bears. Now there may be some hard evidence that a new kind of insecticides called neonicotinoids could be weakening and killing bees. And since bees are critical to the production of more than a quarter of our food, new evidence of a danger is nothing to sneeze at.

The study, led by Reinhard Stöger of Nottingham University, demonstrated that just 2 parts per billion of the neonicotinoid called imidacloprid had an effect on the workings of some honeybee genes. Genes involved in combating toxins and other functions were affected so that cells basically had to work a lot harder. These kinds of changes are known to shorten the lifespan of fruit flies (the most studied insect in the work) and to reduce the numbers reaching adulthood.

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So it's not that the insecticide is outright killing bees (unless they are exposed to a massive dose). It's a lot more subtle. The larvae of the honeybees in the study could still grow and develop in the presence of imidacloprid, the researchers explained, but their development was compromised. This also makes bees more vulnerable to other stresses, such as disease or mites or even difficult weather. And since there are always other stresses, the insecticide puts bees at greater risk.

The study was published in the scientific journal PLOS ONE, and appears to support the recent decision by the European Commission to ban three neonicotinoids because they are suspected of killing bees. U.S. researchers are still trying to determine if low doses of neonicotinoids are causing enough effects to threaten bees.

Ironically, this class of insecticide was developed in the mid-1990s partially because they were less toxic to honeybees than the previously used organophosphate and carbamate insecticides, according to the U.S. Department of Agriculture.

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Since then several studies have been done using unrealistically high doses of neonicotinoids that showed effects on honeybees. There has also not yet been a clear connection made between these insecticides and Colony Collapse Disorder, which has been a major threat to honeybees in recent years.  Read.