Targeting the honey bee gut parasite Nosema ceranae with siRNA positively affects gut bacteria

BACKGROUND: Gut microbial communities can contribute positively and negatively to host health. So far, eight core bacterial taxonomic clusters have been reported in honey bees. These bacteria are involved in host metabolism and defenses. Nosema ceranae is a gut intracellular parasite of honey bees which destroys epithelial cells and gut tissue integrity. Studies have shown protective impacts of honey bee gut microbiota towards N. ceranae infection. However, the impacts of N. ceranae on the relative abundance of honey bee gut microbiota remains unclear, and has been confounded during prior infection assays which resulted in the co-inoculation of bacteria during Nosema challenges. We used a novel method, the suppression of N. ceranae with specific siRNAs, to measure the impacts of Nosema on the gut microbiome. RESULTS: Suppressing N. ceranae led to significant positive effects on microbial abundance. Nevertheless, 15 bacterial taxa, including three core taxa, were negatively correlated with N. ceranae levels. In particular, one co-regulated group of 7 bacteria was significantly negatively correlated with N. ceranae levels. CONCLUSIONS: N. ceranae are negatively correlated with the abundance of 15 identified bacteria. Our results provide insights into interactions between gut microbes and N. ceranae during infection.