TORONTO - Canadian beekeepers have launched a proposed class-action lawsuit against two chemical companies Bayer Inc. and Syngenta International AG and their parent companies for making neonicotinoid pesticides which are alleged to be linked to the death of bees in large numbers.

In a class action lawsuit filed Tuesday by Sun Parlor Honey Ltd. and Munro Honey, two of Ontario's largest honey producers, in the Ontario Superior Court on behalf of all Canadian beekeepers, have alleged that the pesticides produced by Beyer and Syngenta, specifically those containing imidacloprid, clothianidin and thiomethoxam are alleged to be linked to bee death.

"The chronic effects of the use of the Neonicotinoids are felt by Canada's Beekeepers annually, and include: bee deaths; impaired reproduction; immune suppression; behavioral abnormalities resulting in hive loss; reduced honey production; impacts on the quality of honey; contamination of hive equipment; loss of Queen Bees; breeding stock; and difficulties fulfilling honey product or pollination contracts

"Pesticides containing imidacloprid, clothianidin and thiomethoxam have been shown to adversely impact the survival, growth and health of Bees vital to Canada's agriculture," the Ontario Beekeepers Association announced Wednesday, clarifying that while the industry body had helped with the research, it was not a part of lawsuit, which is still to be classified as a class action suit.

The Canadian bee keepers have sought around $450 million general, specific and punitive damages from the pesticide manufacturing companies.

The two family-owned Ontario businesses allege that Bayer Inc. and Syngenta International AG were negligent in their development and distribution of neonicotinoids, as well as permitting or failing to prevent damages to beekeepers.

They allege that the two companies also knew or ought to have known that the insecticides, which are applied to crops, would cause damage.

None of the allegations have been tested in court and the two companies were not immediately available for comment.

A Health Canada report has suggested that seeds treated with neonicotinoids contributed to the majority of the bee deaths in Ontario and Quebec in 2012, likely due to exposure of the pesticide-laced dust during planting.

The Canadian Association of Professional Apiculturists has said that the overall number of bee colonies in Canada has increased over the years, although the annual "winter loss" reported by beekeepers averaged 25 per cent, well above the acceptable level of 15 per cent.

The losses were particularly pronounced in Ontario, where 58 per cent of bees didn't survive the winter, while other provinces lost on average about 19 per cent.

While the association's survey pointed to the weather as the main culprit for the bee deaths, apiculturists in Ontario and Quebec also listed acute and chronic pesticide damage or insufficient recovery from pesticide exposure last year as contributing factors.

The European Commission restricted the use of the pesticides for two years and Ontario has indicated it will move toward regulating them, due to concerns over bee health.

Bayer maintains that the risk to bees from the pesticide is low, and it has recommended ways that farmers can minimize bees' exposure to the pesticide.