Dicer regulates Nosema ceranae proliferation in honeybees

osema ceranae is a microsporidian parasite which infects the honey bee mid‐gut epithelium. The protein coding gene Dicer, is lost in most microsporidian genomes, but is present in N. ceranae. By feeding infected honey bees with small interfering RNA targeting the N. ceranae gene coding Dicer (siRNA‐Dicer), we found that N. ceranae spore loads were significantly reduced. In addition, over 10% of total parasite protein‐coding genes showed significantly divergent expression profiles after siRNA‐Dicer treatment. Parasite genes for cell proliferation, ABC transporters and hexokinase were down‐regulated at 3 days post infection (dpi), a key point in the middle of parasite replication cycles. In addition, genes involved in metabolic pathways of honey bees and N. ceranae showed significant co‐expression. Furthermore, the siRNA‐Dicer treatment partly reversed the expression patterns of honey bee genes. The honey bee gene mucin‐2‐like showed significantly up‐regulation in the siRNA‐Dicer group compared with the infection group continually at 4, 5, 6 days post infection, suggesting that the siRNA‐Dicer feeding promoted the strength of the mucus barrier resulted from interrupted parasite proliferation. As the gene Dicer broadly regulate N. ceranae proliferation and honey bee metabolism, our data suggest the RNAi pathway is an important infection strategy for N. ceranae This article is protected by copyright. All rights reserved