Impacts of Apis cerana gut microbes on Nosema ceranae proliferation in Apis mellifera

The gut microbiota is a complex ecosystem including both beneficial and harmful microbes, which is essential for the metabolism, health and immunity of the host. Fecal microbiota transplantation (FMT) is an effective treatment for diseases of altered intestinal microbiota. Nosema ceranae, a parasitic fungus in intestinal epithelial cells, destroys the honey bee's gut integrity. This study provided the first report that the number of spores was significantly lower in the native host (Asian honey bee) compared with the novel host (European honey bee). The treatment effect of FMT was denoted by feeding the gut tissue solution from the original host to the new host. The results showed that FMT did not significantly decrease the spore load but enhanced the expression levels of immune genes in the Toll pathway. Our data confirmed that the native host inhibits N. ceranae proliferation. Our data suggest microbes of the native host could be an alternative approach to treat the parasite in the novel host.