Does diet breadth affect the complexity of the phytophagous insect microbiota? The case study of Chrysomelidae

Abstract

Chrysomelidae is a family of phytophagous insects with a highly variable degree of trophic specialization. The aim of this study is to test whether species feeding on different plants (generalists) harbour more complex microbiotas than those feeding on a few or a single plant species (specialists). The microbiota of representative leaf beetle species was characterized with a metabarcoding approach targeting V1-V2 and V4 regions of the bacterial 16S rRNA. Almost all the analysed species harbour at least one reproductive manipulator bacteria (e.g., Wolbachia, Rickettsia). Two putative primary symbionts, previously isolated only from a single species (Bromius obscurus), have been detected in two species of the same subfamily, suggesting a widespread symbiosis in Eumolpinae. Surprisingly, the well-known aphid symbiont Buchnera is well represented in the microbiota of Orsodacne humeralis. Moreover, in this study, using Hill numbers to dissect the components of the microbiota diversity (abundant and rare bacteria), it has been demonstrated that generalist insect species harbour a more diversified microbiota than specialists. The higher microbiota diversity associated with a wider host-plant spectrum could be seen as an adaptive trait, conferring new metabolic potential useful to expand the diet breath, or as a result of environmental stochastic acquisition conveyed by diet.

Maternal and host effects mediate the adaptive expansion and contraction of the microbiome during ontogeny in a holometabolous, polyphagous insect

“…Furthermore, flies may share their microbiomes in common oviposition sites and through adult food (Guo et al, 2017; Zaada et al, 2019), and pupation occurs in the microbe‐rich soil habitat, in contrast to microbe‐poor vermiculite in the laboratory (Barraza et al, 2020). Recent reports show that in leaf beetles (Coleoptera: Chrysomelidae) generalists harbour a more diversified microbiota than specialists (Brunetti et al, 2022), that diet shifts (fruit host change) can alter less abundant taxa more than abundant ones and that rare taxa that do not belong to the core community may drive gut bacterial community composition (Benjamino et al, 2018; Hendrycks et al, 2022). Moreover, rare taxa contribute disproportionally to community dynamics through various mechanisms over time and in a variety of environments (Jousset et al, 2017; Shade et al, 2014).…”

Urbanization reduces gut bacterial microbiome diversity in a specialist ground beetle, Carabus convexus

“…Recently, a few studies have used this approach for the analysis of the gut bacterial microbiome (e.g. Brunetti et al., 2022; Littleford‐Colquhoun et al., 2019). Another powerful scalable diversity method, incorporating several classical diversity measures and measuring diversity across the continuous abundance‐spectrum of taxa, is based on the Rényi diversity (entropy) function (Maurer & McGill, 2011).…”

Both host and diet shape bacterial communities of predatory mites

“…Email: zhangbo05@caas.cn and xuxuenong@caas.cn shown to affect the gut microbiome, directly since food may inoculate bacteria to insect gut, or indirectly by promoting the growth of specific bacteria (Chouaia et al, 2019). The higher microbiota diversity associated with a wider diet width could be perceived as an adaptive trait (Brunetti et al, 2022).…”

“…The higher microbiota diversity associated with a wider diet width could be perceived as an adaptive trait (Brunetti et al. , 2022).…”