Bacterial and fungal gut communities of Agrilus mali at different developmental stages and fed different diets

Abstract

Agrilus mali (Coleoptera: Buprestidae) is an invasive wood borer pest that has caused considerable damage to the Xinjiang wild fruit forest. In this study, we investigated the bacterial and fungal intestinal microbial communities of A. mali during different developmental stages, including larvae, pupae and newly eclosed adults or fed different diets (leaves of Malus halliana and Malus pumila) using Illumina MiSeq high-throughput sequencing technology. The results showed that microbial alpha diversity first increased and then decreased during the developmental stages, with the most dominant bacteria and fungi exhibiting the dynamic patterns "Decrease", "Increase" and "Fluctuation". With respect to the different diets, the bacterial communities were similar between the newly eclosed adults and adults fed M. pumila leaves, while the structure of the fungal communities showed great differences between newly eclosed adults and adults fed different diets. Through a co-correlation network analysis, we observed complex microbial interactions among bacterial and fungal taxa that were associated with potential diverse functions and intricate biological processes in the intestinal microbiota of A. mali. Overall, the results of this study demonstrated that the invasive insect A. mali harbours diverse, dynamic, and presumably multifunctional microbial communities, an understanding of which could improve our ability to develop more effective management approaches to control A. mali.

Figure 1

Microbial diversity patterns for A. mali gut microbiotas. Alpha-diversity in bacterial (A,C) and fungal (B,D) gut communities of A. mali gut. Beta-diversity in bacterial (E) and fungal (F) gut communities estimated via principal coordinate analysis (PCoA) based on Bray-Curtis distance.

Figure 2

Dynamic patterns of bacterial and fungal communities during the development of A. mali gut microbiotas, as determined using cluster analysis. The 40 genera with the highest relative abundances were selected and clustered into three groups on the basis of similar profiles (displayed as heatmaps). Each row in the heatmap has been standardized to have a mean of zero and a standard deviation of one. The intensity of the colour in the heatmap is proportional to the standardized relative abundances of the taxa.

Figure 3

Pie charts of the bacterial and fungal OTU abundances in gut microbial communities of A. mali fed different diets of Halliana and Pumila leaves. The taxonomic information of the OTUs with the six highest relative abundances are displayed in the legends.

Figure 4

Co-correlation network of microbial bacteria and fungus genera in the A. mali gut microbiota. A connection indicates for Spearman’s correlation with a coefficient >0.6 (positive correlation, red edges) or <−0.6 (negative correlation, blue edges) and a significant (P < 0.01) correlation. The size of each node is proportional to the relative abundance. Diamonds indicate bacteria, and triangles indicate fungus. The nodes were coloured by phylum.

Figure 5

Venn diagram of the bacterial and fungal OTUs in different gut microbiotas of A. mali.