In Vivo Pyro-SIP Assessing Active Gut Microbiota of the Cotton Leafworm, Spodoptera littoralis

Abstract

The gut microbiota is of crucial importance for the host with considerable metabolic activity. Although great efforts have been made toward characterizing microbial diversity, measuring components' metabolic activity surprisingly hasn't kept pace. Here we combined pyrosequencing of amplified 16S rRNA genes with in vivo stable isotope probing (Pyro-SIP) to unmask metabolically active bacteria in the gut of cotton leafworm (Spodoptera littoralis), a polyphagous insect herbivore that consumes large amounts of plant material in a short time, liberating abundant glucose in the alimentary canal as a most important carbon and energy source for both host and active gut bacteria. With 13C glucose as the trophic link, Pyro-SIP revealed that a relatively simple but distinctive gut microbiota co-developed with the host, both metabolic activity and composition shifting throughout larval stages. Pantoea, Citrobacter and Clostridium were particularly active in early-instar, likely the core functional populations linked to nutritional upgrading. Enterococcus was the single predominant genus in the community, and it was essentially stable and metabolically active in the larval lifespan. Based on that Enterococci formed biofilm-like layers on the gut epithelium and that the isolated strains showed antimicrobial properties, Enterococcus may be able to establish a colonization resistance effect in the gut against potentially harmful microbes from outside. Not only does this establish the first in-depth inventory of the gut microbiota of a model organism from the mostly phytophagous Lepidoptera, but this pilot study shows that Pyro-SIP can rapidly gain insight into the gut microbiota's metabolic activity with high resolution and high precision.

Death Becomes Them: Bacterial Community Dynamics and Stilbene Antibiotic Production in Cadavers of Galleria mellonella Killed by Heterorhabditis and Photorhabdus spp

“…Importantly, our negative-control sample with no DNA input contained only 3% Enterococcus 16S rRNA sequences and instead was dominated by sequences identified as Streptococcus, Veillonella, or Parvimonas. Together, these results both validate the ability of our approach to detect signal over noise and also support previously published observations on the prevalence of Enterococcus in certain insects (49)(50)(51)(52)(53).…”

Effect of Different Lignocellulosic Diets on Bacterial Microbiota and Hydrolytic Enzyme Activities in the Gut of the Cotton Boll Weevil (Anthonomus grandis)

“…On the other hand, an important decrease in Proteobacteria occurred with CS diets; in this case, we could assign a high number of Spirochaetes OTUs. The same predominant groups have been previously reported in other weevils ( Rhynchophorus ferrugines and Rhynchophorus Vulneratus ), beetles ( Pachisoma endroedyi , Pachisoma striatum , Megetra cancellata , Epicauta longicollis , Gonasida inferna and Calosoma peregrinator ), cotton leafworm ( Spodoptera littoralis ), higher termites ( Nasutitermes aquilinus and Cortaritermes fulviceps ), honey bee ( Apis mellifera ), planthopper ( Lycorma delicatula ) and yellow ladybird ( Illeis koebelei ) (Colman et al, 2012; Shao et al, 2014; Yun et al, 2014; Ben Guerrero et al, 2015; Montagna et al, 2015; Franzini et al, 2016). Furthermore, Spirochaetes have been reported previously as a dominant component of the termite gut microbiota (Warnecke et al, 2007; Husseneder et al, 2010; Boucias et al, 2013; Benjamino and Graf, 2016).…”

Pathogenicity of bacteria isolated from gut of Spodoptera litura (Lepidoptera: Noctuidae) and fitness costs of insect associated with consumption of bacteria

“…Although variety of bacterial phyla including Firmicules, Proteobacteria, Actinobacteria, Bacteroidetes, Clostridiales, Cyanobacteria, etc. have been isolated from lepidopteran larvae (Tang et al, 2012;Gayatri Priya et al, 2012;Shao et al, 2014), but the role of these gut bacteria in lepidopetran survival and fitness is not well understood.…”