Diet breadth and exploitation of exotic plants shift the core microbiome of tropical herbivorous beetles

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 8 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 <2 plant types (specialists) versus 9+ plants (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 complementary 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. 33 The beetle genus Cephaloleia has evolved in association with tropical ginger plants and for many species 34 their specific host plant associations are known. Here we show that the core microbiome of six closely-35 related Costa Rican Cephaloleia species comprises only 8 bacterial groups, including members of the 36 Acinetobacter, Enterobacteriacea, Pseudomonas, Lactococcus, and Comamonas. The Acinetobacter and 37 Enterobacteriacea together accounted for 35% of the total average 16S rRNA ribotypes recovered from all 38 specimens. Further, microbiome diversity and community structure was significantly linked to beetle diet 39 breadth, between those foraging on <2 plant types (specialists) versus 9+ plants (generalists). 40 Moraxellaceae, Enterobacteriaceae, and Pseudomonadaceae were highly prevalent in specialist species, 41 and also present in eggs, while Rickettsiaceae associated exclusively with generalist beetles. Bacteria 42 isolated from Cephaloleia digestive systems had complementary capabilities and suggested a possible 43 beneficial role in both digestion of plant-based compounds, including xylose, mannitol, and pectin, and 44 possible detoxification, via lipases. Cephaloleia species are currently expanding their diets to include 45 exotic invasive plants, yet it is unknown whether their microbial community plays a role in this transition. 46 In this study, colonization of invasive plants was correlated with a dysbiosis of the microbiome, 47 suggesting a possible relationship between gut bacteria and niche adaptation. 49 I...

Aphid Species Specializing on Milkweed Have Distinct Bacterial Symbiont Communities

“…In contrast, recent work in Costa Rican rolled-leaf beetles (Cephaloleia spp.) shows diet breadth is linked to microbiome diversity and community structure [21]. Previous research also indicates the composition of aphid microbial communities are structured by host plant [11,15,16,20,22,24,43,44] and heritable bacterial symbionts are involved in expanding diet breadth [23,25].…”

“…Further research investigating the generalist-specialist gradient using herbivores that feed across multiple plant families is needed to clarify the extent to which diet breadth shapes microbial communities (e.g. [21]).…”

“…Insect microbiomes consist of varying combinations of heritable symbionts and exible pools of environmentally acquired microbes, but how host plant range shapes the taxonomic and functional diversity of these communities is relatively unexplored [5,[21][22][23]. Microbial communities of specialist herbivores may be less diverse relative generalist species that possibly require a larger microbial repertoire to successfully colonize highly variable hosts or simply acquire greater environmental microbial diversity from feeding on a broader host plant range [5,21]. Alternatively, overlapping host plant range could result in selection for common microbes needed for successful colonization across different herbivore species due to similarities in nutritional ecology or defensive chemistry.…”

Exogenous and endogenous microbiomes of wild-caught Phormia regina (Diptera: Calliphoridae) flies from a suburban farm by 16S rRNA gene sequencing

“…87 suggested they aided in the digestion of plant nectar consumed by Aedes albopictus mosquitoes. It was also suggested that they may help detoxify defensive plant compounds for tropical herbivorous beetles 88 . They also secrete antiparasitic compounds in the guts of several insects 89 .…”

Aphid species specializing on milkweed harbor taxonomically similar bacterial communities that differ in richness and relative abundance of core symbionts

“…Insect microbiomes consist of varying combinations of heritable symbionts and exible pools of environmentally acquired microbes, but how host plant range shapes the taxonomic and functional diversity of these communities is [21][22][23]relatively unexplored [5,[24][25][26]. Variation in host plant range can in uence the assembly of microbial communities and dynamics of symbiotic partnerships.…”