From ScienceDaily:

Penn State researchers have found that native pollinators, like wild bees and wasps, are infected by the same viral diseases as honey bees and that these viruses are transmitted via pollen. This multi-institutional study provides new insights into viral infections in native pollinators, suggesting that viral diseases may be key factors impacting pollinator populations.

According to Diana Cox-Foster, co-author and professor of entomology at Penn State, pollinator populations have declined for various reasons, including ribonucleic acid (RNA) viruses, which are emerging as a serious threat. "RNA viruses are suspected as major contributors to Colony Collapse Disorder (CCD), where honey bee colonies die with few or no bees left in the hives.”

Bees One of Many Pollinators Infected by Virus Implicated in Colony Collapse Disorder