Host intestinal microbiota adaptive changes following Paranosema locustae infection and mechanism of chronic pathogenesis.

Paranosema locustae infection reduces the abundance and diversity of the intestinal bacteria in locusts, although the microbial adaptive changes and the underlying mechanism of chronic pathogenesis remain unclear. In this study, the intestinal microbial changes in Calliptamus italicus (Linnaeus, 1758) (Orthoptera: Acrididae) were analyzed with metagenomic sequencing after P. locustae infection. Results showed that the diversity of intestinal microbial communities in C. italicus declined after P. locustae infection, while the abundance of infection-specific taxa in C. italicus in the experimental groups was significantly higher than those in the control groups, irrespective of sex (P<0.05). The populations of opportunistic pathogenic bacteria such as Klebsiella aerogenes and Enterococcus faecalis increased significantly (P < 0.05). Meanwhile, the abundances of probiotics such as Pediococcus acidilactici and Enterobacter hormaechei increased significantly (P <0.05), which could inhibit the pathogenicity of P. locustae. The results suggested that the interplay of changes in the species and quantities of probiotics and pathogenic bacteria in the intestine of C. italicus after P. locustae infection was an important factor contributing to the difficulty of P. locustae in quickly breaching the host defense system and to its chronic pathogenicity.