Nosema ceranae, a new parasite in Thai honeybees

Adult workers of Apis cerana, Apis florea and Apis mellifera from colonies heavily infected with Nosema ceranae were selected for molecular analyses of the parasite. PCR-specific 16S rRNA primers were designed, cloned, sequenced and compared to GenBank entries. The sequenced products corresponded to N. ceranae. We then infected A. cerana with N. ceranae spores isolated from A. florea workers. Newly emerged bees from healthy colonies were fed 10,000, 20,000 and 40,000 spores/bee. There were significant dosage dependent differences in bee infection and survival rates. The ratio of infected cells to non-infected cells increased at 6, 10 and 14 d post infection. In addition, hypopharyngeal glands of bees from the control group had significantly higher protein concentrations than infected groups. Bees infected with 40,000 spores/bee had the lowest protein concentrations. Thus, N. ceranae isolated from A. florea is capable of infecting another bee species, impairing hypopharyngeal gland protein production and reducing bee survival in A. cerana.