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New research: If used properly, neonics do not harm bee colonies

New research: If used properly, neonics do not harm bee colonies

U of G researchers urge the use of best management practices

By Kate Ayers

Staff Reporter


Neonicotinoid pesticides commonly used on flowering crops are not harmful when properly handled and applied, a recent University of Guelph study says.

Keith Solomon, a toxicologist and professor, and Gladys Stephenson, an adjunct professor, found that three widely used neonicotinoid pesticides do not pose any health risks to honeybee colonies, according to Tuesday’s university release.

“It’s not so much the individual bee that matters, it’s the colony or the hive,” Solomon said to today.

“There is only one reproductive unit in the colony, which is the queen. All the other bees are there to support her and to raise the new worker bees. So, if a few of those die from exposure to a pesticide or from cold weather … as long as you don’t remove all of them, the hive has the capacity to tolerate that.”

The researchers looked at 170 unpublished studies that Bayer and Syngenta had submitted to regulatory agencies, as well as 64 peer-reviewed papers, according to the release.

In the studies the U of G team looked at, researchers grew crops from treated seed. Once the plants were in flower, scientists put bees onto these crops in tents. So, the bees could only feed on these crops. Researchers examined the effect these condition had on the hive.

“In some cases, researchers saw a little bit of mortality of the bees but the hives continued to do their thing. There was no reduction in the production of honey, there was no significant reduction in the amount of hive that was devoted to larvae and to breed. And the queen was unaffected,” Solomon explained.

The studies looked at Bayer’s clothianidin and imidacloprid, and Syngenta’s thiamethoxam.

“At least for honeybees, these products are not a major concern. Use of these neonics under good agricultural practices does not present a risk to honeybees at the level of the colony,” Solomon said in the release.

“Many studies look at effects of insecticides on individual bees. What regulations try to protect is the colony – the reproductive unit,” he explained.

The scientists still stressed, however, that “good agricultural practices” are critical. For instance, producers should make sure seeds are coated and planted suitably. These practices help to prevent bees from encountering airborne seed treatment during planting. 

Although neonics may not be the cause of deaths in honeybee colonies, various environmental and anthropogenic influences can contribute to poor bee health.

“Bees and other pollinators are affected by potentially harmful factors, including long-distance movement of colonies for crop pollination as well as mites and viruses, weather, insufficient food and varying beekeeping practices,” the researchers said in the release.

However, these types of pesticides may be harmful to other pollinators and individual honeybees, the researchers noted.

The findings are published in the Journal of Toxicology and Environmental Health-B.


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