Worker genetic diversity and infection by Nosema apis in honey bee colonies

The hypothesis that parasites and pathogens select for polyandry in eusocia l Hymenoptera was tested, using the honey bee Apis mellifera and its micros poridian parasite Nosema apis. Five honey bee colonies with low and five wi th high worker generic diversity were infected with N. apis spores. At 54-5 6 days after inoculation, parasite spores in the workers' midguts were coun ted to determine whether there was a greater variation of infection intensi ty (spore counts per worker) in high-diversity colonies than in low-diversi ty ones. In ail colonies there were two discrete sets of workers, with few or many parasite spores. To compare the variations of infection intensity b etween two colony groups, coefficients of variation were calculated for all workers examined, and for the slightly infected and strongly infected work ers. The percentages of slightly infected workers in the low- and high-dive rsity groups were also compared. None of the comparisons between low- and h igh-diversity colonies showed significant differences, therefore no relatio n was found between honey bee workers' genetic diversity and their infectio n with N. apis.