High incidence of infection of an undescribed microsporidium (Microspora) in the communal bee Andrena scotica (Hymenoptera, Andrenidae)

We document the abundance and distribution of the spores of an undescribed species of microsporidium within its host, the communal bee Andrena scotica, and relationships between this parasite and its host. Only the host's adipose tissue (fat bodies) appeared infected, with up to 118 x 10 super(6) spores per bee. All hosts at one field site were infected. High spore load within hosts appeared to curtail female reproductive activity. However, we were unable to discern the microsporidium's effects on male fecundity in that some males with a high spore load did undertake mate searching activity. Longevities of naturally infected. A scotica males and females in a flight cage were apparently unaffected by the microsporidium. Spores were found in A scotica from other field sites but not in other species of bees, suggesting the microsporidium has a high degree of host specificity.