Two manufacturers of crop pesticides are facing a class action lawsuit over claims that their products are causing the deaths of bee colonies.

Bayer Cropscience Inc. and Syngenta Canada Inc. are accused of negligence in their manufacture, sale and distribution of neonicotinoid pesticides, specifically those containing imidacloprid, clothianidin and thiomethoxam, CBC News reported.

Such pesticides are widely used as a coating on corn, soybean and canola seeds in Canada to protect the plants from crop pests such as aphids.

According to the Statement of Claim, the widespread use of neonicotinoids in Ontario has caused beekeepers to suffer significant losses and damage, including killed or weakened bees; non-productive queens and bee colonies; contaminated wax, combs and hives; reduced honey production and lost profits; costs incurred to meet honey and pollination contracts; and increased labor, equipment and supply expenses.

Studies have shown that bees exposed to the pesticides have smaller colonies and may have trouble navigating, CBC News said.

The lawsuit, which seeks to recover more than $400 million in damages, was submitted by two of Ontario's biggest honey producers, Sun Parlor Honey and Munro Honey, on behalf of all Canadian beekeepers. It was filed in the Ontario Superior Court on Tuesday by law firm Siskinds LLP.

Commenting on the action, the Ontario Beekeepers' Association said that, while it was not directly involved in the lawsuit, it supports "any effort that could help beekeepers recover losses caused by the overuse of neonicotinoids."

More than 30 beekeepers have signed up to participate in the case.