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

Abstract

Monochamus saltuarius (Coleoptera: Cerambycidae) is an important native pest in the pine forests of northeast China and a dispersing vector of an invasive species Bursaphelenchus xylophilus. To investigate the bacterial gut diversity of M. saltuarius larvae in different host species, and infer the role of symbiotic bacteria in host adaptation, we used 16S rRNA gene Illumina sequencing and liquid chromatography-mass spectrometry metabolomics processing to obtain and compare the composition of the bacterial community and metabolites in the midguts of larvae feeding on three host tree species: Pinus koraiensis, Pinus sylvestris var. mongolica, and Pinus tabuliformis. Metabolomics in xylem samples from the three aforementioned hosts were also performed. Proteobacteria and Firmicutes were the predominant bacterial phyla in the larval gut. At the genus level, Klebsiella, unclassified_f__Enterobacteriaceae, Lactococcus, and Burkholderia–Caballeronia–Paraburkholderia were most dominant in P. koraiensis and P. sylvestris var. mongolica feeders, while Burkholderia–Caballeronia–Paraburkholderia, Dyella, Pseudoxanthomonas, and Mycobacterium were most dominant in P. tabuliformis feeders. Bacterial communities were similar in diversity in P. koraiensis and P. sylvestris var. mongolica feeders, while communities were highly diverse in P. tabuliformis feeders. Compared with the other two tree species, P. tabuliformis xylems had more diverse and abundant secondary metabolites, while larvae feeding on these trees had a stronger metabolic capacity for secondary metabolites than the other two host feeders. Correlation analysis of the association of microorganisms with metabolic features showed that dominant bacterial genera in P. tabuliformis feeders were more negatively correlated with plant secondary metabolites than those of other host tree feeders.

Species‐specific primers for rapid detection of Monochamus saltuarius, an effective vector of Bursaphelenchus xylophilus in China

“…But then, the nematode has continuously adapted to low temperatures and has gradually expanded northward from tropical, subtropical, and south central warm‐temperate up to mid‐temperate climatic zone over recent years. As previously reported, M. saltuarius became the insect vector of B. xylophilus in Northeast China (Ge et al., 2021; Hou et al., 2021; Li et al., 2020; Pan, Li, et al., 2020). Though both the flight capacity (Zhang et al., 2007) and the number of nematodes carriage (Kobayashi et al., 1984; Pan, Li, et al., 2020; Zhan et al., 2014) were relatively weaker for M. saltuarius than M .…”

“…But then, the nematode has continuously adapted to low temperatures and has gradually expanded northward from tropical, subtropical, and south central warm-temperate up to mid-temperate climatic zone over recent years. As previously reported, M. saltuarius became the insect vector of B. xylophilus in Northeast China (Ge et al, 2021;Hou et al, 2021;Li et al, 2020;. Though both the flight capacity (Zhang et al, 2007) and the number of nematodes carriage (Kobayashi et al, 1984;Zhan et al, 2014) were relatively weaker for M. saltuarius than M. alternatus, M. saltuarius represented the main dispersal vector endemic to the mid-temperate zone of China which has small or no M. alternatus population (Figure 1) (Wu et al, 2021;Yang et al, 2003; for increasing resolution at lower taxonomic levels (Avise et al, 1987;Brown et al, 1979;Wilson et al, 1985).…”

“…Until 2017, M. saltuarius was found in an affected P. tabuliformis forest in Fengcheng, Liaoning Province . After a series of prospective studies, M. saltuarius was established as the main insect vector of B. xylophilus in the mid-temperate zone of China where there was no distribution of M. alternatus (Ge et al, 2021;Hou et al, 2021;Li et al, 2020;Wu et al, 2021;Zheng et al, 2021). M. saltuarius is ubiquitous in pine forests in Liaoning, Jilin, Heilongjiang, Inner Mongolia and other places in middle and cold temperate zone of China.…”

Invasion History of the Pinewood Nematode Bursaphelenchus xylophilus Influences the Abundance of Serratia sp. in Pupal Chambers and Tracheae of Insect-Vector Monochamus alternatus

“…For example, Serratia marcescens is lethal if it enters the hemolymph and can successfully evade the immune system of the insect (Raymann et al, 2017 , 2018 ). Interestingly, some vector beetle adults and larvae (e.g., M. alternatus, M. galloprovincialis , and M. saltuarius ) that have a phoretic relationship with PWN can also carry genus Serratia in their gut microbiota (Vicente et al, 2013 ; Alves et al, 2016 ; Guo et al, 2020 ; Ge et al, 2021 ) without adverse effects under normal conditions.…”

Seasonal Shifts in Cold Tolerance and the Composition of the Gut Microbiome of Dendroctonus valens LeConte Occur Concurrently

“…Insects are chronically infected by microorganisms, most of which are beneficial or even obligatory to their insect hosts [1,2]. The large majority of these infecting microbes are colonized in the gut of their host, where they aid the digestion of unpalatable food components, improve undernourished diets, help their hosts defend against predators, parasites, and pathogens, and even affect host physiological action by neuroendocrine signaling [1][2][3][4]. Therefore, changes in the microbial community can affect a number of host phenotypes [2].…”