Characterization of Spodoptera litura Gut Bacteria and Their Role in Feeding and Growth of the Host.

Xiaofeng Xia,Minsheng You,Xinping Tao,Junhan Lin,Bomiao Lan

doi:10.3389/fmicb.2020.01492

Xiaofeng Xia, Minsheng You + Show 3 more

Open Access

https://doi.org/10.3389/fmicb.2020.01492

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Abstract

Insect gut microbes play important roles in host feeding, digestion, immunity, growth and development. Spodoptera litura is an important agricultural pest distributed of global importance. In the present study, diversity and functions of the gut bacteria in S. litura are investigated based on the approaches of metagenomics and denaturing gradient gel electrophoresis (DGGE). The results showed that the gut bacterial diversity of S. litura reared on taro leaves or an artificial diet, were similar at the phylum level, as both were mainly composed of Proteobacteria, but differed significantly at the order level. Spodoptera litura reared on taro leaves (Sl-tar) had gut biota mainly comprised of Enterobacteriales and Lactobacillales, while those reared on artificial diet (Sl-art) predominantly contained Pseudomonadales and Enterobacteriales, suggesting that gut bacteria composition was closely related to the insect’s diet. We found that feeding and growth of S. litura were significantly reduced when individuals were treated with antibiotics, but could be both restored to a certain extent after reimporting gut bacteria, indicating that gut bacteria are important for feeding, digestion, and utilization of food in S. litura. Metagenomic sequencing of gut microbes revealed that the gut bacteria encode a large number of enzymes involved in digestion, detoxification, and nutrient supply, implying that the gut microbes may be essential for improving the efficiency of food utilization in S. litura.

Highlights

The insect gut hosts a large number of microbes, many of which play an important role for the insect in feeding, digestion, immunity, growth, development, and even insecticide resistance
A total of 7,641.81 Mb and 7,334.18 Mb raw data of Metagenomic for the gut microbes of S. litura feeding on taro leaf (Sl-tar) and artificial diet (Sl-art), respectively, were obtained using the Illumina HiSeq2500 platform
The proportions of other orders differed (Figure 2B and Supplementary Table S4). These results demonstrate that the gut bacteria of the two lines were similar at the phylum level, there was a significant difference at the order level

Summary

Introduction

The insect gut hosts a large number of microbes, many of which play an important role for the insect in feeding, digestion, immunity, growth, development, and even insecticide resistance. These functions are achieved through variety of enzymes they produce that can, among other things, promote the degradation of toxic substances, synthesis of amino acids, metabolization, and utilization of carbohydrates (Hansen and Moran, 2011; Kikuchi et al, 2012; Engel and Moran, 2013; Chomwong et al, 2018; Xia et al, 2018). Apis mellifera, microbes play a role in degrading pectin found in pollen walls, permitting digestion by the bees (Engel et al, 2012)

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