Bacterial Communities Associated with the Pine Wilt Disease Insect Vector Monochamus alternatus (Coleoptera: Cerambycidae) during the Larvae and Pupae Stages

Abstract

Monochamus alternatus is an important insect pest in pine forests of southern China and the dispersing vector of the pine wood nematode, Bursaphelenchus xylophilus, which leads to pine wilt disease (PWD). Microbiome of M. alternatus may contribute to survival of larvae in the host pine trees. In order to investigate the intestinal bacterial structure of M. alternatus during the larvae and pupae stages in host trees, and infer the function of symbiotic bacteria, we used 16S rRNA gene Illumina sequencing to obtain and compare the bacterial community composition in the foregut, midgut, and hindgut of larvae, pupal intestines, larval galleries, and pupal chambers of M. alternatus. The diversity of the bacterial community in larval intestines and pupal intestines were similar, as well as was significantly greater in larval galleries and pupal chambers. Although there were differences in bacterial compositions in different samples, similar components were also found. Proteobacteria and Firmicutes were the two most dominant phyla in all samples, and genera Enterobacter, Raoultella, Serratia, Lactococcus, and Pseudomonas were dominant in both the intestinal samples and plant tissue samples. Enterobacter was the most abundant genus in larval intestines, and Serratia was dominant in pupal intestine. The functions of these dominant and specific bacteria were also predicted through metagenomic analyses. These bacteria may help M. alternatus degrade cellulose and pinene. The specific role of symbiotic bacteria in the infection cycle of PWD also warrants further study in the future.

Gut Bacteria Associated With Monochamus saltuarius (Coleoptera: Cerambycidae) and Their Possible Roles in Host Plant Adaptations

“…Bacterial phyla in M. saltuarius larval gut were dominated by Proteobacteria and Firmicutes. Represented by Monochamus and Anoplophora species, these typical taxa were repeatedly reported as dominant phyla in the guts of many Cerambycidae species ( Schloss et al, 2006 ; Rizzi et al, 2013 ; Vicente et al, 2013 ; Hu et al, 2017 ; Kim et al, 2017 ; Chen et al, 2020 ), and are even the predominant phyla in the guts of insects ( Yun et al, 2014 ). The high abundance levels of these phyla may be due to active recruitment by insects, or to taxa of these phyla being more likely than other bacterial communities to invade and colonize insect hosts ( Jones et al, 2013 ).…”

“…On the contrary, high abundant genera in the larval guts were quiet diverse according to different host plants: in the guts of P. koraiensis and P. sylvestris var. mongolica feeders, Klebsiella , unclassified _f__Enterobacteriaceae , Lactococcus , and Burkholderia–Caballeronia–Paraburkholderia were most dominant, these typical taxa are often thought ro be associated with xylophagous insects ( Reid et al, 2011 ; Morales-Jiménez et al, 2012 ; Rizzi et al, 2013 ; Berasategui et al, 2017 ; Chen et al, 2020 ), as they can associate with their host by supplementing specifically required forms of nitrogen and other nutrients thus ensure a normal development ( Behar et al, 2005 ). In addition, Burkholderia species are terpene-degrading species [e.g., Burkholderia xenovorans degrades diterpene resin acids and can utilize diterpenes as a sole carbon source ( Smith et al, 2007 )], and some symbionts in this genus also have fenitrothion-degrading capabilities ( Kikuchi et al, 2012 ).…”

Localization of Bacterial Communities within Gut Compartments acrossCephalotesTurtle Ants

“…Some insects have a crop with abundant and diverse microbes ( 55 , 56 ). However, more commonly the crop contains bacteria in low abundance or is almost entirely lacking microbes, possibly due to routine evacuation ( 57 , 58 ).…”

We and herbivores eat endophytes

“…Enterobacter was the most common in larval and Serratia in pupal intestines. These bacteria may help to degrade the terpene pinene found in pines (Chen et al 2020).…”