The Southern green shield bug, Nezara viridula, is an invasive piercing and
sucking pest insect that feeds on leguminous crops and poses a threat to
global food production.
More...The Southern green shield bug, Nezara viridula, is an invasive piercing and
sucking pest insect that feeds on leguminous crops and poses a threat to
global food production. Insects are known to live in a close relationship
with microorganisms, which provide hosts with unique capabilities, such as
resistance to toxic secondary plant metabolites, e.g. 3-nitropropionic acid.
In this study, we sequenced isolated members of N. viridula microbial gut
community and analysed phylogenetic markers of toxin-degrading genes. We
combined it with culturing eight bacterial isolates on 3-nitroproponic
acid-rich agar plates and in liquid media to assess their resistance and
ability to metabolize toxins. We showed that core- and transient-associated
gut microorganisms had different tolerance to high concentrations of the
toxin and that six strains detoxified 3-nitropropionic acid. Using
transcriptomics and untargeted metabolomics approaches, we revealed that the
toxin might influence the metabolism and transport of amino acids,
particularly leucine biosynthesis. Also, we investigated pairwise microbial
interactions between members of the gut community are found that core
microbiota shapes the composition of the N. viridula microbiome by favouring
the growth of symbiotic microorganisms and suppression of transient
bacteria. With this research, we provided novel insights into the microbial
role in shaping the insect gut community and demonstrated that N. viridula
harbours many toxin-degrading bacteria that could support its resistance to
plant defences.
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