Researchers have found a parasite in every Ontario bee sample they analyzed in part of an effort to prevent a recurrence of the disaster that wiped out a third of the province's honeybee colonies last winter.

The Ontario Beekeepers' Association experts collected about 446 bee samples from 25 keepers and every one contained Nosema apis, a single-celled protozoan that affects the bees' digestive systems. More than half of the samples had a more aggressive strain called Nosema ceranae, the association said in a release Tuesday.

A third of Ontario's honeybee colonies were killed last winter.
(CBC)

But that wasn't the only problem. "The bees were already under stress from a high incidence of varroa mites as well as the environment. Due to a wet fall, the bees were not able to gather enough pollen to use as a protein source for raising young bees in the spring," said Alison Skinner, an association expert.

Ernesto Guzman, a University of Guelph environmental biology professor, said recently that the varroa mite and Nosema ceranae may have caused last winter's high mortality.

"It may be one of the main factors in Ontario's colony loss," Guzman said in a release in October, "but because it's so new, the prevalence of this parasite in the province and how it affects colony mortality have never been studied."

Nosema ceranae was discovered in Ontario in May, but has been blamed for large colony losses in Europe.

The Maritimes have also seen an unusually high number of bee deaths recently and an entomologist said in May that Nosema ceranae might have contributed. At the time, Agriculture Canada's leading bee scientist, Steve Pernal, said he thought unusual weather conditions were more likely to blame.

The Ontario Beekeepers' Association has given Guzman nearly $278,000 to investigate the parasite.

Meanwhile, the association's tech transfer team is promoting the only known treatment for Nosema, a drug called Fumagilin B that can kill Nosema spores. The prognosis is good, the association said.

Almost 27,000 of the 76,000 hives in Ontario were killed last year, and many of the remaining colonies were badly weakened.

While the immediate financial loss was relatively small — about $6 million — the problem highlighted the role of bees in pollinating other crops. Honey-bee pollination is responsible for one-third of food, the association said.

Nosema divides once it enters a bee, and the bees defecate more often (called bee dysentery) to try and remove the parasite. If they defecate in the hive, which they may do in the winter, other bees are affected.

The bee problems in Ontario and other provinces appear to be separate from Colony Collapse Disorder, which affected almost a quarter of United States earlier in 2007.