According to a study authored by Mark Brown of the University of London, wild bumblebee populations around the globe are declining. A major source of the decline is the spillover of parasites, pathogens, and disease from managed honeybee hives.
Co-auther Matthias Furst says the research doesn't quite prove diseases are transmitted from honeybees to bumblebees. Bumblebees are likely to pick up diseases when they go to flowers after infected honeybees or when they invade honeybee hives and steal nectar.
The study did not address colony collapse disorder.