Structure of the Gut and Ovary, with Associated Microbiota Across Life Stages in the Striped Stem Borer Chilo suppressalis (Lepidoptera: Crambidae)

Abstract The striped stem borer Chilo suppressalis (Lepidoptera: Crambidae) was one of the most serious pests of water-oat Zizania latifolia. Microbiota associated with gut, ovary and egg influenced a wide variety of their host traits (such as fitness and immunity), and understand the microbiota structure and its dynamics across C. suppressalis’s life was a prerequisite for comprehending the symbiotic relationship between C. suppressalis and its microbiota as well as transmission pattern. Herein, we characterized the structure of the gut, ovary and associated microbiota of a striped stem borer C. suppressalis. The gut was structurally divided into foregut, midgut and hindgut, and its structure and ultrastructure were very different between adults and larvae, however, this was not documented in detailed before. Microbiota in gut, ovary and egg showed variation in relative abundance. Proteobacteria and Firmicutes became the predominant phyla, and Bacillaceae, Enterobacteriaceae, Enterococcaceae, Halomonadaceae, Moraxellaceae and Streptococcaceae were shared among the gut, ovary and egg of C. suppressalis, although they exhibited different relative abundance. The highest bacteria diversity was found in the larval midgut. The bacterial genera distribution showed great differences due to developmental stage, diet and gut compartments. Our results demonstrated that the developmental stage, diet and gut compartment had a considerable impact on gut microbiota of C. suppressalis. Genera Klebsiella, Enterococcus, Bacillus, Citrobacter and Lactococcus were core microbiota, which transferred from the gut to the ovaries and eggs. Our study provided an important insight into investigation of insect-bacteria symbioses as well as its transmission pattern, so as to perform effective biocontrol of this species.