It has only been recently that the widely used neonicotinoid pesticides were discovered to be responsible for bee population declines. This has resulted in three of these pesticides now being banned in Europe and two will be phased out in Canada, and that is good news for the bees.
Based on the phase-out over time of neonicotinoids, chemical companies have been searching for something to replace the pest killer. However, newly developed pesticides could be just as bad for pollinators if allowed to be marketed. One such pesticide is Sulfoxaflor, the first branded sulfoximine-based insecticide,
Sulfoximine-based insecticides are either licensed for use or under consideration for licensing in several worldwide markets, including the European Union, where certain neonicotinoids (imidacloprid, clothianidin, and thiamethoxam) are now banned from agricultural use outside of permanent greenhouse structures Currently, 47 countries allow the use of sulfoximine-based pesticides.
Sulfoxaflor was approved two years ago for use in Canada. It is trademarked as Isoclast and sold by AgriGroSciences under the brand name Closer. Health Canada is aware of the study and says it is “reviewing it to determine whether further action is required.”
Sulfoxaflor, the branded product, was given EPA approval in the United States in October 2016, although it is a limited approval, meaning it is supposed to be used selectively on crops that don’t attract pollinators or “for crop- production scenarios that minimize or eliminate potential exposure to bees.”
A new study sheds light on sulfoximine dangers
A new study published in the journal Nature on August 15, 2018, has just reported that these pesticides could be just as harmful as the ones that they are replacing.
Ph.D. student Harry Siviter, alongside Professor Mark Brown, and Dr. Ellouise Leadbeater, all from the School of Biological Sciences at Royal Holloway, tested the effects of the substance on bumblebee colonies. In their research, the bumblebees were exposed to low doses of the new pesticide in the lab (similar to what they would be exposed to in an agricultural field) and transferred to a field.
Sulfoxaflor reduced both the size of bumblebee colonies and the number of male offspring they produced – with a 54 percent reduction in the total number of sexual offspring produced in exposed colonies. That is a drastic reduction.
Harry Siviter said: “Sulfoximine-based insecticides are a likely successor and are being registered for use globally. Our results show that sulfoxaflor can have a negative impact on the reproductive output of bumblebee colonies under certain conditions.”
Dr. Elli Leadbeater added: “Our study highlights that stressors that do not directly kill bees can still have damaging effects further down the line because the health of the colony depends on the health of its workforce.”
But as ZME Science notes, the study also points out the need for this kind of an investigation to be done before a pesticide is ever approved for commercial use.
