The Canadian Government is planning to phase out two types of neonicotinoid pesticides it says have been linked to deaths of aquatic insects and bees.

Health Canada’s Pest Management Regulatory Agency (PMRA) said it would phase out, over three to five years, the outdoor use of thiamethoxam, made by Syngenta AG, and clothianidin, made by Bayer AG.

PMRA said that the measure will have an initial 90-day consultation period, with a final decision due to be reached in late 2019.

It is also looking to decide on a third neonic, Bayer’s imidacloprid, and whether to phase it out by the end of this year.

Meanwhile, the U.S. is reviewing neonics and plans to seek public comment on proposed action next spring, a spokesperson for the U.S. Environmental Protection Agency told Reuters.

In April EU countries backed a proposal to ban almost all outdoor use of neonics, while in June 2017 a large European study was published which found that exposure to treated crops reduced the overwintering success of honeybee colonies.

Alternative pesticides may pose risk for bees

In a separate development, a recent study published in Nature journal has found that sulfoximine pesticides - a potential neonicotinoid replacement - may also present a risk for bees.

The research found that bee colonies exposed to plants treated with the pesticides produced fewer female workers and had a decrease of 54% in reproductive offspring.

"Our results show that sulfoxaflor can have a negative impact on the reproductive output of bumblebee colonies under certain conditions," study researcher Harry Siviter of Royal Holloway University told the BBC.

These impairments in colony growth and reproduction are similar to those observed in comparable neonicotinoid-exposure studies, the study found.

According to the study, such similarity can be expected as “both insecticides (…) affect insects by binding to the same neurotransmitter receptors”.

"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," Dr. Ellouise Leadbeater was quoted as saying.

Sulfoximine pesticides are currently approved for use in countries including China, Canada and Australia, according to the BBC.

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