Within gut physicochemical variation does not correspond to distinct resident fungal and bacterial communities in the tree-killing xylophage, Anoplophora glabripennis

• Published in: Journal of insect physiology Vol. 102; pp. 27 - 35
• Main Authors: Mason, Charles J., Long, David C., McCarthy, Elizabeth M., Nagachar, Nivedita, Rosa, Cristina, Scully, Erin D., Tien, Ming, Hoover, Kelli
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.10.2017
• Subjects: 16S; Animals; Asian longhorned beetle; Bacteria - classification; Bacteria - genetics; Bacteria - isolation & purification; Cerambycidae; Coleoptera - growth & development; Coleoptera - microbiology; Coleoptera - physiology; Digestion; Digestive System - chemistry; Digestive System - metabolism; Digestive System - microbiology; DNA, Ribosomal Spacer - genetics; Fungi - classification; Fungi - genetics; Fungi - isolation & purification; Gastrointestinal Microbiome; Hydrogen-Ion Concentration; ITS; Larva - growth & development; Larva - microbiology; Larva - physiology; Massachusetts; Microbiome; New York; Oxidation-Reduction; Oxygen - metabolism; Redox potential; RNA, Bacterial - genetics; RNA, Fungal - genetics; RNA, Ribosomal, 16S - genetics; Cerambycidae; Asian longhorned beetle; pH; ITS; Redox potential; Digestion; 16S; Microbiome
• ISSN: 0022-1910; 1879-1611
• DOI: 10.1016/j.jinsphys.2017.08.003

[Display omitted] •We assessed gut physicochemical and microbial aspects of Anoplophora glabripennis.•Anterior to posterior, pH increased and redox potential decreased.•Lumen oxygen levels were low and did not change longitudinally.•Fungal and bacterial assemblages did not differ between gut regions.•Different A. glabripennis populations had different microbial communities. Insect guts harbor diverse microbial assemblages that can be influenced by multiple factors, including gut physiology and interactions by the host with its environment. The Asian longhorned beetle (A. glabripennis; Cerambycidae: Lamiinae) is an invasive tree–killing insect that harbors a diverse consortium of fungal and bacterial gut associates that provision nutrients and facilitate lignocellulose digestion. The physicochemical conditions of the A. glabripennis gut and how these conditions may influence the microbial composition across gut regions are unknown. In this study, we used microsensors to measure in situ oxygen concentrations, pH, and redox potential along the length of the A. glabripennis larval gut from two North American populations. We then analyzed and compared bacterial and fungal gut communities of A. glabripennis within individual hosts along the length of the gut using 16S and ITS1 amplicon sequencing. The A. glabripennis midgut lumen was relatively anoxic (<0.01kPa) with a pH gradient from 5.5 to 9, moving anterior to posterior. Redox potential was higher in the anterior midgut relative to posterior regions. No differences in physicochemistry were measured between the two populations of the beetle, but the two populations harbored different communities of bacteria and fungi. However, microbial composition of the A. glabripennis gut microbiota did not differ among gut regions despite physicochemical differences. Unlike other insect systems that have distinct gut compartmentalization and corresponding microbial assemblages, the A. glabripennis gut lacks dramatic morphological modifications, which may explain why discrete microbial community structures were not found along the digestive system.