MONTREAL -- Seeding is over for this year on Canadian corn and soy farms. But a student's research suggests the consequences on bees could last a long time.

He has collected data that showed apiaries installed less than three kilometres from insecticide-treated fields had a three times higher rate of mortality.

Human beings should take note. Pollination is responsible for 70 per cent of cultivated plants, and for 35 per cent of humans' overall food consumption. Fewer bees means fewer plants -- notably apples, strawberries, cucumbers -- and could ultimately mean a drop in the food supply.

The Quebec master's student, Olivier Samson-Robert, had attempted to put a figure on the noted decline in bee populations and detemine how much of it was linked to a certain type of insecticide.

The Laval University student released the first part of his study about bees' mortality around fields treated with neonicotinoid insecticides, one of the most widely used insecticides worldwide.

"The neonicotinoid insecticide causes a higher mortality rate," Samson-Robert said in an interview.

Neonicotinoid insecticides have been allowed in Canada since 2004.

They are chemically similar to nicotine, which has a long tradition in agriculture. Tobacco has been used as an insecticide since at least the 15th century, according to the U.S. Environmental Protection Agency.

Samson-Robert said that insecticide is ubiquitous, with 99 per cent of corn seeds and 50 per cent of soy seeds in Quebec coated with it, over a land mass that covers 500,000 hectares of the province.

Particles from that insecticide escape into the air when the seeds are planted, Samson-Robert said. He argued that using a funneling device to steer the seeds straighter into the ground when seeding would help reduce contamination.

He said particles from insecticides fall onto bees, or onto the flowers that bees are visiting. Particles are present as well in the water that bees drink, he said.

According to Jean-Pierre Chapleau, spokesman for the Quebec Beekeepers' Federation, beekeepers want neonicotinoid insecticides banned.

"Neonicotinoid insecticides are overused," he says.

Chapleau said that beekeepers don't blame farmers, because they can't buy seeds that have not been treated with insecticides even if they want to.

The industry says that's not accurate.

Gilles Corno is regional director for Pride Seeds. He says it's possible to buy corn seeds in Canada that are not treated with neonicotinoids, if ordered at a certain time of the year.

He says Samson-Robert's findings are more anecdotal than scientific -- "observations and not a study," he says.

Samson-Robert based his work on the observation of 12 apiaries in Monteregie and Estrie regions, every two days during seeding time from the beginning of May to mid-June.

Proving the effect of insecticides isn't so simple.

Chapleau says that, even if the contamination is real, it's not easy to spot in real-time.

Swarms of bees aren't dying suddenly but over time, he says, and they have more and more health issues that lead to increased mortality rates.

"Beekeepers don't report problems because they don't see anything that prompts them to take a picture or to collect samples," says Chapleau.

"It's a chronic issue. We can't see it directly."

For him, neonicotinoid insecticides are not the only cause of bees' mortality.

He said varroa mites kill more bees than pesticides.

But pesticides do cause economic damage, Chapleau said.

He said they make apiaries less efficient -- with bees losing their olfactory memory and sense of direction. Over the last 10 years, in Quebec, the apiary's honey productivity has decreased 30 per cent, he said.

"It's not because we can't precisely assess the damages and it's not because there is no acute intoxication that there are no problems," Chapleau said. "A five-per-cent or a 10-per-cent decrease of production is serious for beekeepers...

"That situation didn't exist before neonicotinoid insecticides were introduced."

Some researchers wonder whether neonicotinoids provide any benefit here at all.

Several studies suggest the quantity of insect pests in the North American soil doesn't justify the use of neonicotinoid insecticides.

That argument is made in Quebec in a study done by the CEROM research centre, which is funded by seed production companies, the Quebec government, and agri-food industry producers.

It also appears in a U.S. study by Christian Krupke, associate professor at Purdue University, who suggests there are no yield benefits from using treated corn seeds.

The Government of Canada has no current plan to ban neonicotinoids.

Health Canada's Pest Management Regulatory Agency, which authorized neonicotinoid insecticides for commercialization in 2004, announced an evaluation of the situation in 2012 after bees' increased mortality was reported.

"Health Canada is closely monitoring treated-seed planting and conducting analyses of bee incidents that are occurring this year," spokesman Sean Upton said in an email.

"We do not feel a broad suspension is warranted at this time. Other countries, the United States and Australia for example, have the same position."