New Study reported here:

A research team from Bern, Switzerland has found that male European honey bees, or drones, are much more susceptible than female European honey bees, known as workers, to a fungal intestinal parasite called Nosema ceranae. Originally from Asia, Nosema ceranae has rapidly spread throughout the world in recent years, and may contribute to the high number of colony deaths now observed in many regions of the northern hemisphere. These findings demonstrate the delicate nature of male honey bees, which are important to honey bee colony reproduction, to a well-distributed parasite.