Gut microbiota ofSpodoptera frugiperda(J.E. Smith) larvae as revealed by metatranscriptomic analysis

Abstract

The invasive fall armyworm, Spodoptera frugiperda (J.E. Smith; Lepidoptera: Noctuidae), is considered one of the most harmful pests in corn, rice and cotton crops and has developed resistance to the most widespread methods used to control it, chemical insecticides and transgenic crops based on Bt toxins. On the other hand, gut microbiota plays an important role in the insect's fitness, and metatranscriptomic analyses of the insect host are an invaluable tool for identifying new pest control targets. Notwithstanding, there are extremely few reports on the functionally active profile of the gut microbiota in insects, especially in lepidopterans. Moreover, most studies have only described the bacterial community even though all the components of the microbiota, Bacteria, Archaea, fungi, protozoa and viruses, influence different physiological aspects of the insect host. This is the first time an unbiased and comprehensive metatranscriptomic approach has been used to describe the taxonomic and functional profile of the gut microbiota of S. frugiperda larvae, both bacterial and non‐bacterial. We identified novel and very active components which were putatively playing an important nutritional role, such as ammonia‐oxidizing Archaea and Bacteria, and a xylan‐ and hemicellulose‐degrading Actinobacteria. This analysis also allowed us to identify potential biocontrol agents.

Microbiome of the larvae of Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae) from maize plants

“…This finding corroborates the recent report by Rozadilla et al (2020) who also detected the presence of archaea in the gut of S. frugiperda larvae using high-throughput pyrosequencing of 16S rDNA, and it represented a high proportion of the metabolically active gut microbiota in S. frugiperda. Archaea have been revealed through metagenomic studies to be very diverse and prolific, and they play vital roles in nitrogen cycling in soils (Bates et al, 2011;Edwards et al, 2015;Siles, Öhlinger, Cajthaml, Kistler, & Margesin, 2018;Secil, Sevim, Demirbag, & Demir, 2012).…”

“…Similarly, a study in Kenya using NGS reported 19 major bacteria genera in the gut of S. frugiperda (Gichuhi et al, 2020). The fifth report on S. frugiperda Argentina using high-throughput pyrosequencing of 16S rDNA reported 10 major bacteria genera with other non-bacterial group (Rozadilla et al (2020). In the present study, 20 major bacterial genera were documented.…”

“…There is insufficient information on the roles they play in their host (Gurung et al, 2019) although it has been suggested that they could affect plants (Taffner et al, 2018). In this study, Euryarchaeota was the most dominant archaea phylum followed by has been reported in the hindguts of beetles, cockroaches, termites and millipedes (Brune, 2009;Egert et al, 2005;Hara, Shinzato, Seo, Oshima, & Yamagishi, 2002;Shinzato, Matsumoto, Yamaoka, Oshima, & Yamagishi, 1999;Šustr, Chroňáková, Semanová, Tajovský, & Šimek, 2014;Tinker & Ottesen, 2016). Similarly, shotgun metagenomic analysis of the gut of diamondback moth Plutella xylostella larvae revealed Euryarchaeota DNA in very low proportions (Xia et al, 2017).…”

“…This study revealed that the microbiome of the fall armyworm S. frugiperda larvae were dominated by Proteobacteria followed (Chen et al, 2018) and S. frugiperda (Gichuhi et al, 2020 (Voirol et al, 2018). However, recent studies using high-throughput sequencing (NGS) of 16S rDNA to analyse the gut microbiota of late-instar field-captured H. armigera larvae revealed that Actinobacteria was the dominant phylum followed by Proteobacteria and Firmicutes (Ranjith, ManiChellappan, Harish, Girija, & Nazeem, 2016) and S. frugiperda (Rozadilla et al, 2020).…”

“…(2017) on FAW gut bacteria using culture‐dependent methods to isolate gut bacteria from oral secretions of field‐collected larvae revealed that the bacterial isolates regulated herbivore‐induced defences. A recent study by Rozadilla, Cabrera, Virla, Greco, and McCarthy (2020) using meta‐transcriptomic analysis revealed the presence of novel genes and other components in the gut microbiota of FAW larvae that were being expressed by the community. In this study, we used next‐generation paired‐end amplicon sequencing of 16S rRNA gene to characterize the microbiota of FAW larvae collected from maize plants in Nigeria.…”