Nosema ceranae infects honey bees (Apis mellifera) and contaminates honey in Australia

Polymerase chain reaction (PCR), restriction fragment length polymorphism (RFLP) analysis and microscopy were used to test 307 adult bee and 37 honey samples collected in Australia for the presence of two microsporidia, Nosema ceranae and Nosema apis. N. ceranae was detected in samples from 4 states (Queensland, New South Wales, Victoria and South Australia) and was most commonly found in samples from Queensland where 28 (33.7%) of 83 samples were positive. New South Wales had the second highest prevalence with 15 (15.8%) of 95 samples positive. South Australia and Victoria had 4 (16%) of 25 and 2 (4.5%) of 44 samples positive respectively. N. ceranae was not detected in samples from Western Australia and Tasmania. N. apis was detected in samples from all states. Three honey samples (8.1%) were PCR positive for N. ceranae. These positive honey samples originated from beekeepers in Queensland. Six imported honey samples tested were negative for both Nosema spp.