Several species of bumble bee, including Bombus occidentalis, pictured, are experiencing steep population declines. (ARS photo)

The research finds the American commercial bumble bee industry accidentally helped spread a fungal pathogen of bees.

Scientists hoping to explain widespread declines in wild bumble bee populations conducted the first long-term genetic study of Nosema bombi, a key fungal pathogen of honey bees and bumble bees.

They report in the journal Proceedings of the National Academy of Sciences they found that N. bombi was present in the U.S. as early as 1980, well before several species of wild bumble bees started to go missing across the country.

Critically, they also found that N. bombi infections in large-scale commercial bumble bee pollination operations coincided with infections and declines in wild bumble bees.

We used molecular techniques to screen thousands of bumble bees to track Nosema infections before and after the bees began to decline, says University of Illinois entomology professor Sydney Cameron, who led the new research.

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