CBC News: What's killing Canadian honeybees? (VIDEO)

Beekeeper John Van Blyderveen is troubled by the silence in his laneway in Ontario's Oxford County.

The familiar summertime buzz of bees hovering over the lush cherry blossom trees is noticeably absent. The flowers sit untouched.

"This is extremely unusual for this being a bee farm, there are no bees here," Blyderveen says. "This is really sad."

This increasingly familiar scene, which is playing out across North America and Europe, worries beekeepers, farmers and scientists who have been tracking the collapse of honeybee colonies over the past decade.

In the process, two main camps have emerged, vigorously debating the root causes of the decline.

Some scientists and insecticide companies suggest the bees are being overrun by an infestation of mites, while other observers suggest seeds coated with neonicotinoid insecticide – or "neonics" – are to blame.

It's a puzzle with huge implications. Bees and other pollinators are responsible for ensuring most fruit and vegetable crops around the world mature into food.

Most sources suggest about one-third of the food we eat is reliant on pollinators, and Bloomberg Business Week estimates bee pollination affects "$200 billion worth of crops annually." View