Diet breadth and exploitation of exotic plants shift the core microbiome of Cephaloleia, a group of tropical herbivorous beetles.

Chelsea L Blankenchip,Shana K Goffredi,H Elizabeth Braker,Dana E Michels

doi:10.7717/peerj.4793

Abstract

The beetle genus Cephaloleia has evolved in association with tropical ginger plants and for many species their specific host plant associations are known. Here we show that the core microbiome of six closely related Costa Rican Cephaloleia species comprises only eight bacterial groups, including members of the Acinetobacter, Enterobacteriacea, Pseudomonas, Lactococcus, and Comamonas. The Acinetobacter and Enterobacteriacea together accounted for 35% of the total average 16S rRNA ribotypes recovered from all specimens. Further, microbiome diversity and community structure was significantly linked to beetle diet breadth, between those foraging on less than two plant types (specialists) versus over nine plant types (generalists). Moraxellaceae, Enterobacteriaceae, and Pseudomonadaceae were highly prevalent in specialist species, and also present in eggs, while Rickettsiaceae associated exclusively with generalist beetles. Bacteria isolated from Cephaloleia digestive systems had distinct capabilities and suggested a possible beneficial role in both digestion of plant-based compounds, including xylose, mannitol, and pectin, and possible detoxification, via lipases. Cephaloleia species are currently expanding their diets to include exotic invasive plants, yet it is unknown whether their microbial community plays a role in this transition. In this study, colonization of invasive plants was correlated with a dysbiosis of the microbiome, suggesting a possible relationship between gut bacteria and niche adaptation.

Highlights

Beneficial symbioses are the rule, rather than the exception, and the discovery and elucidation of the role of symbiotic microorganisms to animal life has emerged as an important area of research
We show that the core microbiome of six closely related Cephaloleia species primarily includes the Moraxellaceae, Enterobacteriaceae, and Pseudomonadaceae, and that diet breadth is significantly linked to microbiome diversity and community structure
Costa Rican beetle species within the genus Cephaloleia, with known diet breadths ranging from generalist to specialist, were analyzed for their associated gut microbial community

Summary

Introduction

Beneficial symbioses are the rule, rather than the exception, and the discovery and elucidation of the role of symbiotic microorganisms to animal life has emerged as an important area of research. Persistent bacterial partnerships are well documented and believed to play a critical role in host adaptation to specific niches. Microbiological studies on aphids, stinkbugs, psyllids, white flies, mealybugs, and leafhoppers have provided insights into the physiological, ecological, and evolutionary history of bacterial symbioses with insects that primarily consume plant sap How to cite this article Blankenchip et al (2018), Diet breadth and exploitation of exotic plants shift the core microbiome of Cephaloleia, a group of tropical herbivorous beetles. It is widely accepted that symbioses allow insect herbivores to exploit plants more effectively, little specific evidence has been reported for chewing phytophagous insects, in the understudied tropical rainforests (Genta et al, 2006; Kuriwada et al, 2010; Hansen & Moran, 2014)

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