Nosema ceranae escapes fumagillin control in honey bees:

PLOS research abstract:

Nosema ceranae, a microsporidian pathogen described from Asian honey bees, was discovered infecting European honey bees coincident with early reports of Colony Collapse Disorder (CCD) and has been suggested to be a factor in honey bee declines. Use of fumagillin, the only known reliable treatment for the naturally occurring Nosema apis, subsequently increased but controversial field results were reported for N. ceranae. Fumagillin suppresses reproduction of microsporidia but disease prevalence and hive performance in treated apiaries were similar to untreated apiaries 6 months after treatment. We compared responses of N. apis and N. ceranae to the antibiotic at concentrations that simulated fumagillin degradation in hives during the honey bee foraging season when use of the drug is discontinued. N. ceranae spore production recovered at a higher fumagillin concentration thanN. apis. At lower fumagillin concentrations, significantly more infective N. ceranae spores were produced in treated bees than in untreated infected bees. Protein profiles of bees fed fumagillin confirmed our hypothesis that fumagillin affects bee physiology at concentrations that no longer suppress N. ceranae. Use of fumagillin may increase the prevalence of N. ceranae and is potentially a factor in replacement of N. apis by N. ceranae in US apiaries. Read more.